Existing Annotations Review

GO Term	Evidence	Action	Reason
GO:0005524 ATP binding	IEA GO_REF:0000002	KEEP AS NON CORE	Summary: Retain as non-core. ATP binding supports the MutL conformational cycle, while ATP hydrolysis is the more informative catalytic function. Reason: Correct property of the N-terminal GHKL ATPase domain.
GO:0006259 DNA metabolic process	IEA GO_REF:0000117	MARK AS OVER ANNOTATED	Summary: This broad parent process adds no information beyond mismatch repair. Reason: GO:0006298 is the direct pathway term.
GO:0006298 mismatch repair	IEA GO_REF:0000120	ACCEPT	Summary: Accept. Transient loss of MutL activity was used directly to expose the mismatch-correction hierarchy in KT2440. Reason: Core process with direct P. putida genetic support. Supporting Evidence: PMID:31599106 permanent deletion of mutS or transient loss of mutL activity
GO:0016887 ATP hydrolysis activity	IEA GO_REF:0000120	ACCEPT	Summary: Accept as the catalytic function of the conserved GHKL ATPase domain. Reason: Pseudomonas MutL ATPase-site mutations cause defective mismatch repair, and Q88DD1 retains the conserved domain. Supporting Evidence: PMID:11952911 residue known to be essential for its ATPase activity.
GO:0030983 mismatched DNA binding	IEA GO_REF:0000002	REMOVE	Summary: Remove. MutL can bind DNA in the repair complex, but mismatch-specific recognition is the role of MutS; direct mismatch specificity is not established for MutL. Reason: InterPro propagation conflates recruitment to mismatch-bound MutS with mismatch sensing.
GO:0032300 mismatch repair complex	IEA GO_REF:0000120	ACCEPT	Summary: Accept. MutL is a defining component recruited by mismatch-bound MutS. Reason: Correct complex membership without assigning MutS's recognition function to MutL.
GO:0140664 ATP-dependent DNA damage sensor activity	IEA GO_REF:0000002	REMOVE	Summary: Remove. MutL is an ATP-dependent coordinator and endonuclease recruited by MutS, not the protein that initially senses the mismatch. Reason: The sensor term belongs to MutS in this pathway.
GO:1990238 double-stranded DNA endonuclease activity	ISS PMID:23969026 Analysis of DNA structure and sequence requirements for Pseu...	NEW	Summary: Add by close-ortholog inference. Pseudomonas aeruginosa MutL directly nicks duplex plasmid DNA, and a reproducible global alignment finds 521 identical residues among 627 aligned residue pairs (83.1%) between its reviewed protein Q9HUL8 and KT2440 Q88DD1. Reason: The direct biochemical exemplar is a close Pseudomonas ortholog with the same MutH-independent architecture; a direct Q88DD1 assay is still needed. Supporting Evidence: PMID:23969026 PaMutL was able to nick covalently closed circular plasmids file:PSEPK/mutL/mutL-bioinformatics/RESULTS.md of which 521 are identical (83.0941%).

Core Functions

MutL hydrolyzes ATP to coordinate assembly and progression of the MutS-initiated mismatch repair reaction.

Molecular Function:

ATP hydrolysis activity

Directly Involved In:

mismatch repair

In Complex:

mismatch repair complex

Supporting Evidence:

PMID:31599106
permanent deletion of mutS or transient loss of mutL activity
PMID:11952911
residue known to be essential for its ATPase activity.

Q88DD1 is inferred from the close P. aeruginosa ortholog to nick duplex DNA and provide the strand-incision activity required by a MutH-independent mismatch repair pathway.

Molecular Function:

double-stranded DNA endonuclease activity

Directly Involved In:

mismatch repair

In Complex:

mismatch repair complex

Supporting Evidence:

PMID:23969026
PaMutL was able to nick covalently closed circular plasmids
file:PSEPK/mutL/mutL-bioinformatics/RESULTS.md
of which 521 are identical (83.0941%).

References

GO_REF:0000002

Gene Ontology annotation through association of InterPro records with GO terms

GO_REF:0000117

Electronic Gene Ontology annotations created by ARBA machine learning models

GO_REF:0000120

Combined Automated Annotation using Multiple IEA Methods

file:PSEPK/mutL/mutL-uniprot.txt

UniProtKB entry for PSEPK MutL (Q88DD1)

"This protein is involved in the repair of mismatches in DNA."
"required for dam-dependent methyl-directed DNA mismatch repair"

PMID:31599106

Mismatch repair hierarchy of Pseudomonas putida revealed by mutagenic ssDNA recombineering of the pyrF gene.

"permanent deletion of mutS or transient loss of mutL activity"

PMID:11952911

The mismatch repair system (mutS, mutL and uvrD genes) in Pseudomonas aeruginosa: molecular characterization of naturally occurring mutants.

"residue known to be essential for its ATPase activity."

PMID:23969026

Analysis of DNA structure and sequence requirements for Pseudomonas aeruginosa MutL endonuclease activity.

"devoid of MutH is the presence of a MutL homologue with endonuclease activity."
"PaMutL was able to nick covalently closed circular plasmids"

PMID:23922851

Analysis of the interaction interfaces of the N-terminal domain from Pseudomonas aeruginosa MutL.

"C-terminal (CTD) dimerization domain that possesses metal ion-dependent endonuclease activity."

UniProtKB:Q9HUL8

UniProtKB entry for Pseudomonas aeruginosa PAO1 MutL

file:PSEPK/mutL/mutL-bioinformatics/RESULTS.md

Reproducible Q88DD1-Q9HUL8 MutL global protein alignment

The alignment contains 521 identical residues among 627 aligned residue pairs, or 83.0941% identity.

"of which 521 are identical (83.0941%)."

Suggested Experiments

Experiment: Purify Q88DD1 and test metal-dependent nicking of covalently closed duplex DNA with MutS, mismatch-containing substrates, ATP/ADP, and the KT2440 beta clamp; compare catalytic-site and clamp-binding mutants.

Hypothesis: Q88DD1 is the strand-incision endonuclease of KT2440 MMR.

Type: reconstituted MutH-independent mismatch incision assay

Deep Research

Falcon

(mutL-deep-research-falcon.md)

Research Report: *Pseudomonas putida* KT2440 **mutL** (PP_4896; UniProt Q88DD1) — Functional Annotation and Evidence Falcon Edison Scientific Literature 23 citations 2 artifacts 2026-06-11T21:28:50.312519

Edison artifact artifact-00 (text/markdown)

## Context ID: pqac-00000013 I have extracted Figure 3 and the relevant panel from Figure 4. Figure 3 (from page 4) shows the mutation frequencies for RifR and (image/png)

The research report should be a detailed narrative explaining the function, biological processes, and localization of the gene product. Citations should be given for all claims.

You should prioritize authoritative reviews and primary scientific literature when conducting research. You can supplement
this with annotations you find in gene/protein databases, but these can be outdated or inaccurate.

We are specifically interested in the primary function of the gene - for enzymes, what reaction is catalyzed, and what is the substrate specificity? For transporters, what is the substrate? For structural proteins or adapters, what is the broader structural role? For signaling molecules, what is the role in the pathway.

We are interested in where in or outside the cell the gene product carries out its function.

We are also interested in the signaling or biochemical pathways in which the gene functions. We are less interested in broad pleiotropic effects, except where these elucidate the precise role.

Include evidence where possible. We are interested in both experimental evidence as well as inference from structure, evolution, or bioinformatic analysis. Precise studies should be prioritized over high-throughput, where available.

Research Report: Pseudomonas putida KT2440 mutL (PP_4896; UniProt Q88DD1) — Functional Annotation and Evidence

0. Executive summary

The target protein MutL (gene mutL, locus PP_4896, UniProt Q88DD1) in Pseudomonas putida KT2440 is a canonical bacterial mismatch-repair factor required for post-replicative correction of base–base mismatches and small insertion/deletion loops, operating in a MutH-less context (KT2440 encodes MutS and MutL, and lacks MutH and Dam methylation). P. putida MutL is experimentally validated as the key controllable “lever” for tuning mismatch repair (MMR): a dominant-negative allele (mutL E36K) transiently inhibits endogenous MMR, producing up to 438-fold increases in selectable mutation frequencies and enabling efficient genome engineering with low off-target burden (0–3 SNPs) by whole-genome sequencing (WGS). Mechanistically, while direct biochemical measurements of P. putida MutL enzymatic activities were not found in the retrieved organism-specific literature, authoritative bacterial DNA repair reviews support inference that many MutH-less bacterial MutL homologs contain a metal-dependent endonuclease motif and are activated/positioned by interaction with the replication β-clamp (DnaN).

1. Mandatory verification: correct gene/protein identity

1.1 Mapping UniProt context to primary literature

The UniProt target (Q88DD1) is annotated as DNA mismatch repair protein MutL, gene mutL, ordered locus PP_4896, in Pseudomonas putida KT2440. In P. putida KT2440-focused work, MutL is explicitly referenced as PP_4896 and described as a MutL homolog with ~44% amino-acid identity to E. coli MutL (greater conservation in the N-terminal half). (aparicio2020mismatchrepairhierarchy pages 2-3, aparicio2020mismatchrepairhierarchy pages 1-2)

1.2 Avoiding ambiguity with the symbol “mutL”

“mutL” is a widely conserved bacterial gene symbol. The evidence cited below is restricted to:
- MutL/MutS mismatch repair studies in Pseudomonas putida KT2440 derivatives (notably EM42, a KT2440 derivative) (aparicio2020mismatchrepairhierarchy pages 3-5, fernandezcabezon2021spatiotemporalmanipulationof pages 4-5)
- General bacterial mismatch repair reviews used only for mechanistic inference about MutL family function (wozniak2022bacterialdnaexcision pages 10-11, wozniak2022bacterialdnaexcision pages 18-19)

2. Key concepts and definitions (current understanding)

2.1 DNA mismatch repair (MMR)

Bacteria reduce replication error rates via (i) base selection, (ii) proofreading, and (iii) mismatch repair. In MMR, mismatches remaining after replication are recognized and corrected, preventing fixation of point mutations and some small indels. (fernandezcabezon2021spatiotemporalmanipulationof pages 1-2)

2.2 Canonical players and pathway architectures

MutS: mismatch recognition factor.
MutL: matchmaker/coordinator and (in many organisms) the nuclease that initiates strand incision.
MutH: endonuclease used in E. coli methyl-directed MMR; not universal.

A defining feature for P. putida KT2440 is that it encodes mutS and mutL but lacks mutH and dam methylation, implying a methylation-independent, MutH-less MMR mechanism with different strand-discrimination logic than E. coli. (aparicio2020mismatchrepairhierarchy pages 2-3, aparicio2020mismatchrepairhierarchy pages 1-2)

3. MutL (PP_4896) molecular function and mechanism

3.1 Primary biological role in P. putida KT2440

Primary function: MutL maintains genome fidelity by participating in MMR to recognize/resolve base–base mismatches introduced during replication or during recombineering-mediated introduction of mismatches.

Functional evidence in P. putida is strongest from genetic/engineering perturbations:
- Permanent MMR disruption via ΔmutS strongly elevates mutational regime and removes mismatch-type bias, consistent with MutS–MutL dependence. (aparicio2020mismatchrepairhierarchy pages 2-3, aparicio2020mismatchrepairhierarchy pages 3-5)
- Transient suppression of MutL via dominant-negative mutL E36K makes mismatches introduced by ssDNA recombineering escape repair and become inherited. (aparicio2020mismatchrepairhierarchy pages 3-5, aparicio2020mismatchrepairhierarchy pages 5-6)

3.2 Interaction partners and pathway placement

Organism-specific interaction mapping (e.g., co-immunoprecipitation) was not retrieved; however, the P. putida functional data and broader MMR models support that MutL operates downstream of mismatch recognition by MutS.

In an MMR hierarchy study, P. putida strains were engineered in three MMR states: wild-type, ΔmutS (MMR-null), and wild-type with MutL E36K transiently inhibiting MMR. Convergence of recombineering efficiencies between mismatch types upon MutL suppression demonstrates MutL’s functional centrality in the pathway. (aparicio2020mismatchrepairhierarchy pages 3-5)

3.3 Enzymatic activities: what is known vs inferred

3.3.1 Evidence-supported inferences for MutH-less systems

A high-authority bacterial DNA repair review reports:
- Many MutL homologs in methylation-independent bacteria contain a conserved metal-dependent endonuclease motif: DQHA(X)2E(X)4E.
- The replication β-clamp (DnaN) binds MutL and can stimulate MutL incision activity; mutating either the endonuclease motif or DnaN-binding motif abolishes MMR in vivo (demonstrated in Bacillus subtilis). (wozniak2022bacterialdnaexcision pages 10-11)

This supports annotation of P. putida MutL as a likely endonuclease-enabled MMR coordinator in a MutH-less setting, but the report explicitly distinguishes this as inference rather than direct biochemical proof for PP_4896. (wozniak2022bacterialdnaexcision pages 10-11)

3.3.2 ATPase/clamp behaviors and “action-at-a-distance” models (recent mechanistic synthesis)

A 2024 review focused on long-range communication in MMR highlights that mismatch repair can involve clamp-like states and long-distance signaling between mismatch sites and distant incision sites, including models involving sliding clamps, DNA looping, and MutL-family oligomerization/assemblies (largely eukaryotic context, but conceptually informative). (collingwood2024actionatadistanceindna pages 4-6, collingwood2024actionatadistanceindna pages 1-3)

Relevance to bacterial MutL annotation: These models provide an expert framework for how MutL-family proteins could coordinate incision and excision at distances from the mismatch, consistent with clamp-coupled recruitment concepts also emphasized in bacterial reviews. (wozniak2022bacterialdnaexcision pages 10-11, collingwood2024actionatadistanceindna pages 4-6)

4. Cellular localization: where MutL acts

Direct subcellular localization microscopy of P. putida MutL (PP_4896) was not identified in the retrieved KT2440-specific sources. However, mechanistic evidence suggests MutL’s effective localization is nucleoid-associated and replisome-coupled, mediated through interaction with the β-clamp (DnaN) in methylation-independent MMR pathways. (wozniak2022bacterialdnaexcision pages 10-11)

5. P. putida KT2440-specific functional phenotypes and quantitative data

5.1 Dominant-negative mutL E36K as a conditional mutator system

5.1.1 Concept and construction

A key engineering strategy in P. putida uses a dominant-negative MutL allele, mutL E36K, designed by analogy to a dominant-negative E. coli MutL variant (equivalent residue position differs: P. putida E36). In P. putida, regulated overexpression of mutL E36K transiently inhibits endogenous MMR, allowing mismatches to become fixed as mutations. (aparicio2020mismatchrepairhierarchy pages 2-3, fernandezcabezon2021spatiotemporalmanipulationof pages 1-2)

5.1.2 Mutation-frequency increases and selectable phenotypes

In P. putida, inducible mutator devices driving mutL E36K expression produced:
- Up to 438-fold increased DNA mutation frequencies (as reported in the study abstract). (fernandezcabezon2021spatiotemporalmanipulationof pages 1-2)
- Accelerated evolution of: (i) streptomycin resistance, (ii) rifampicin resistance, (iii) combined resistance, and (iv) reversion of a synthetic uracil auxotrophy. (fernandezcabezon2021spatiotemporalmanipulationof pages 1-2)

Figure-level quantitative support (mutation frequency assays) is provided in the paper’s mutation-frequency plots. (fernandezcabezon2021spatiotemporalmanipulationof media 4d80bb01)

5.1.3 Statistics for auxotrophy reversion

For a synthetic uracil auxotrophy reversion assay, conditional mutator systems yielded approximately:
- 750 Ura+ mutants per 1 × 10^9 viable cells (cyclohexanone-inducible system)
- 860 Ura+ mutants per 1 × 10^9 viable cells (thermoinducible system)
Controls yielded only 0–4 spontaneous Ura+ mutants under the tested conditions. (fernandezcabezon2021spatiotemporalmanipulationof pages 5-6)

A figure panel documenting these mutation frequencies was retrieved. (fernandezcabezon2021spatiotemporalmanipulationof media 1d27dc75)

5.2 Mismatch recognition hierarchy in P. putida MMR (functional “specificity”)

A P. putida MMR hierarchy was experimentally derived using ssDNA recombineering into pyrF and deep sequencing, yielding a mismatch sensitivity ordering (less to more sensitive):
A:G < C:C < G:A < C:A, A:A, G:G, T:T, T:G, A:C, C:T < G:T, T:C. (aparicio2020mismatchrepairhierarchy pages 5-6)

This hierarchy is a key organism-specific functional insight: it indicates that certain mismatch types (notably G:T and T:C) are strongly corrected by P. putida MMR, which directly impacts editing strategies and expected mutational spectra under MMR suppression. (aparicio2020mismatchrepairhierarchy pages 5-6)

5.3 Genome engineering application and off-target burden

To test whether transient MutL suppression introduces widespread off-target mutations, whole-genome sequencing was performed on clones generated during transient MMR inactivation with mutL E36K.

Result:
- 0–3 SNPs detected in strains transiently expressing mutL E36K.
- 0 mutations detected in the MMR-proficient control strain analyzed. (aparicio2020mismatchrepairhierarchy pages 8-9)

This supports real-world implementation of MutL suppression as a practical genome-editing enabler in P. putida with relatively low background mutation accumulation when used transiently. (aparicio2020mismatchrepairhierarchy pages 8-9)

6. Recent developments (prioritizing 2023–2024)

Direct 2023–2024 P. putida KT2440 MutL primary studies were not retrieved in the tool results; the key organism-specific experimental sources available here are 2020–2021. However, two recent mechanistic syntheses that inform interpretation and annotation are:
- Collingwood et al., 2024-11-xx (Biomolecules): review of long-range communication and clamp/assembly models in mismatch repair, including MutL-family clamp-like states and oligomerization concepts. URL: https://doi.org/10.3390/biom14111442 (collingwood2024actionatadistanceindna pages 4-6)
- Additional authoritative review evidence on MutH-less bacterial MutL endonuclease/clamp coupling from Wozniak & Simmons, 2022-02-xx (Nature Reviews Microbiology), which remains a widely cited up-to-date synthesis for bacterial excision repair pathways. URL: https://doi.org/10.1038/s41579-022-00694-0 (wozniak2022bacterialdnaexcision pages 10-11)

7. Current applications and real-world implementations

7.1 Adaptive laboratory evolution (ALE) and phenotype emergence

Because P. putida has a highly efficient MMR system, controlled transient inhibition via mutL E36K is used as an “accelerator” for evolution-based optimization. In practice, inducible devices allow alternating cycles of mutagenesis and selection, enabling faster emergence of useful phenotypes (antibiotic resistance as a proxy, auxotrophy reversion as a calibration case). (fernandezcabezon2021spatiotemporalmanipulationof pages 1-2, fernandezcabezon2021spatiotemporalmanipulationof pages 5-6)

7.2 Genome editing and recombineering

MMR is a major barrier to ssDNA recombineering because it removes introduced mismatches. In P. putida, co-expression of a recombinase (Rec2) with mutL E36K creates a window in which mismatches can be incorporated across mismatch classes more uniformly, mitigating mismatch-type bias that otherwise differs by ~two orders of magnitude in recombineering outcomes. (aparicio2020mismatchrepairhierarchy pages 3-5)

The low WGS off-target burden (0–3 SNPs) under transient MutL inhibition supports its use in strain engineering where maintaining general genomic integrity is important. (aparicio2020mismatchrepairhierarchy pages 8-9)

8. Expert opinions and analysis (authoritative interpretations)

Two high-level expert interpretations supported by review and primary evidence:
1. MutH-less bacteria rely on MutL endonuclease activity and replisome coupling: review evidence supports that MutL homologs in methylation-independent systems frequently encode an intrinsic nuclease motif and are activated/positioned by β-clamp binding, providing a plausible basis for strand discrimination and incision initiation without MutH/Dam. (wozniak2022bacterialdnaexcision pages 10-11)
2. Mismatch repair requires long-range communication mechanisms: mechanistic reviews emphasize that mismatch repair must coordinate recognition at a mismatch with strand incision/excision at potentially distant sites, and propose models including sliding clamps, looping, and MutL-family assemblies—conceptually consistent with clamp-centered bacterial recruitment logic. (collingwood2024actionatadistanceindna pages 4-6, collingwood2024actionatadistanceindna pages 1-3)

9. Data highlights (recent statistics and quantitative results)

Key quantitative outputs for functional annotation:
- Up to 438-fold increase in DNA mutation frequency using P. putida mutL E36K conditional mutator devices. (fernandezcabezon2021spatiotemporalmanipulationof pages 1-2)
- ~750–860 Ura+ mutants per 10^9 cells under mutator-device conditions vs 0–4 in controls (auxotrophy reversion). (fernandezcabezon2021spatiotemporalmanipulationof pages 5-6)
- 0–3 SNPs detected by WGS after transient mutL E36K expression vs 0 in the MMR+ control. (aparicio2020mismatchrepairhierarchy pages 8-9)
- Mismatch-type sensitivity hierarchy: A:G and C:C least corrected; G:T and T:C most corrected. (aparicio2020mismatchrepairhierarchy pages 5-6)

Figure evidence showing mutation-frequency shifts and Ura+ frequencies is available from the mutator-device paper. (fernandezcabezon2021spatiotemporalmanipulationof media 4d80bb01, fernandezcabezon2021spatiotemporalmanipulationof media 1d27dc75)

10. Evidence-based functional annotation (proposed)

10.1 Molecular function (GO-style narrative)

MutL (PP_4896; Q88DD1) is a mismatch-repair factor that coordinates repair of replication errors in P. putida KT2440, functioning with MutS and acting in a MutH-independent pathway. Genetic perturbation (dominant-negative E36K) demonstrates MutL is essential for suppressing fixation of mismatches and controlling mutation rates. (aparicio2020mismatchrepairhierarchy pages 3-5, fernandezcabezon2021spatiotemporalmanipulationof pages 1-2)

10.2 Reaction/biochemical activity and substrate specificity

Directly evidenced in P. putida: MutL activity suppresses fixation of a broad set of mismatch classes, with mismatch-type dependent efficiencies summarized by a hierarchy derived experimentally. (aparicio2020mismatchrepairhierarchy pages 5-6)
Inferred (not directly shown for PP_4896 in retrieved sources): MutH-less bacterial MutL homologs often provide a metal-dependent endonuclease incision activity via the conserved DQHA(X)2E(X)4E motif and are stimulated by β-clamp binding. (wozniak2022bacterialdnaexcision pages 10-11)

10.3 Cellular localization

Likely cytosolic/nucleoid-associated with functional recruitment to replication forks via β-clamp interactions (inference from MutH-less bacterial systems; P. putida-specific imaging evidence not retrieved). (wozniak2022bacterialdnaexcision pages 10-11)

11. Limitations and evidence gaps

No P. putida KT2440-specific biochemical assays confirming PP_4896 ATPase or endonuclease catalytic activity were retrieved; enzymatic-function statements beyond genetics are inferred from authoritative reviews. (wozniak2022bacterialdnaexcision pages 10-11)
No direct microscopy-based localization of P. putida MutL was retrieved; localization is inferred via clamp-coupling models in MutH-less bacteria. (wozniak2022bacterialdnaexcision pages 10-11)

12. Summary table

Topic	Key points	Best supporting citations
Identity	- Target matches mutL / PP_4896 / UniProt Q88DD1 in Pseudomonas putida KT2440, annotated as a DNA mismatch repair protein MutL. - P. putida KT2440 carries mutS and mutL homologues but lacks mutH and Dam methylation, so it uses a MutH-independent MMR pathway. - PP_4896 shares ~44% amino-acid identity with E. coli MutL, with stronger conservation in the N-terminal region.	Aparicio et al., 2020, Environmental Microbiology, Nov 2020, https://doi.org/10.1111/1462-2920.14814 (aparicio2020mismatchrepairhierarchy pages 2-3, aparicio2020mismatchrepairhierarchy pages 1-2)
Pathway role	- MutL functions in post-replicative DNA mismatch repair (MMR), helping correct replication errors after base selection and proofreading. - In P. putida, active MMR clearly depends at least on MutS and MutL and suppresses inheritance of ssDNA recombineering-generated mismatches. - Transient inhibition of MutL allows mismatches to escape repair and become fixed as chromosomal mutations.	Fernández-Cabezón et al., 2021, ACS Synthetic Biology, Apr 2021, https://doi.org/10.1021/acssynbio.1c00031 (fernandezcabezon2021spatiotemporalmanipulationof pages 1-2); Aparicio et al., 2020, https://doi.org/10.1111/1462-2920.14814 (aparicio2020mismatchrepairhierarchy pages 3-5, aparicio2020mismatchrepairhierarchy pages 8-9)
Activities/domains	- Direct P. putida-specific biochemical assays were not provided in the retrieved papers, so ATPase/endonuclease activities are inferred from conserved bacterial MutL biology rather than demonstrated here. - Authoritative review evidence indicates many MutL homologues in methylation-independent systems carry a metal-dependent endonuclease motif [DQHA(X)2E(X)4E]. - The same review indicates MutL activity is linked to the replication clamp DnaN, whose binding can stimulate MutL endonuclease activity in MutH-independent bacteria.	Wozniak & Simmons, 2022, Nature Reviews Microbiology, Feb 2022, https://doi.org/10.1038/s41579-022-00694-0 (wozniak2022bacterialdnaexcision pages 10-11); Aparicio et al., 2020 discussion/citations, https://doi.org/10.1111/1462-2920.14814 (aparicio2020mismatchrepairhierarchy pages 12-13)
Mismatch recognition hierarchy findings	- Using pyrF-targeted mutagenic ssDNA recombineering, the P. putida MMR hierarchy was reported as A:G < C:C < G:A < C:A, A:A, G:G, T:T, T:G, A:C, C:T < G:T, T:C from less to more sensitive to repair. - Wild-type MMR therefore tolerates some mismatches much more than others; G:T and T:C are among the most strongly repaired. - Transient expression of dominant-negative mutL E36K or permanent ΔmutS largely collapses this bias.	Aparicio et al., 2020, Environmental Microbiology, Nov 2020, https://doi.org/10.1111/1462-2920.14814 (aparicio2020mismatchrepairhierarchy pages 1-2, aparicio2020mismatchrepairhierarchy pages 5-6, aparicio2020mismatchrepairhierarchy pages 8-9)
Mutator devices and phenotypes	- A dominant-negative mutL_E36K allele was engineered in P. putida based on the equivalent inactive/dominant-negative E. coli allele; in KT2440 the homologous residue is E36. - Regulated overexpression of mutL_E36K on broad-host-range plasmids created conditional mutator devices that transiently inhibit endogenous MMR. - These devices accelerated emergence of streptomycin resistance, rifampicin resistance, dual antibiotic resistance, and reversion of a synthetic uracil auxotrophy.	Aparicio et al., 2020, https://doi.org/10.1111/1462-2920.14814 (aparicio2020mismatchrepairhierarchy pages 2-3, aparicio2020mismatchrepairhierarchy pages 3-5); Fernández-Cabezón et al., 2021, https://doi.org/10.1021/acssynbio.1c00031 (fernandezcabezon2021spatiotemporalmanipulationof pages 1-2, fernandezcabezon2021spatiotemporalmanipulationof pages 4-5, fernandezcabezon2021spatiotemporalmanipulationof pages 5-6)
Quantitative mutation frequencies	- In the 2021 mutator-device study, inducible mutL_E36K increased DNA mutation frequencies by up to 438-fold relative to controls. - For uracil prototroph reversion, conditional mutator systems yielded about 750 and 860 Ura+ mutants per 1 × 10^9 viable cells (cyclohexanone- and thermoinducible systems, respectively), whereas controls produced only 0–4 spontaneous Ura+ mutants under the tested conditions. - In recombineering assays, wild-type MMR caused about a two-orders-of-magnitude difference between low-sensitivity (SR; A:G) and high-sensitivity (NR; G:T/C:A) oligos; this gap disappeared with ΔmutS or mutL_E36K expression.	Fernández-Cabezón et al., 2021, ACS Synthetic Biology, Apr 2021, https://doi.org/10.1021/acssynbio.1c00031 (fernandezcabezon2021spatiotemporalmanipulationof pages 1-2, fernandezcabezon2021spatiotemporalmanipulationof pages 4-5, fernandezcabezon2021spatiotemporalmanipulationof pages 5-6, fernandezcabezon2021spatiotemporalmanipulationof media 4d80bb01, fernandezcabezon2021spatiotemporalmanipulationof media 1d27dc75); Aparicio et al., 2020, https://doi.org/10.1111/1462-2920.14814 (aparicio2020mismatchrepairhierarchy pages 3-5, aparicio2020mismatchrepairhierarchy pages 9-10)
Genome-wide off-target mutations	- Whole-genome sequencing of clones generated after transient mutL_E36K expression found 0–3 SNPs in edited strains. - A control MMR-proficient strain analyzed in parallel showed no detectable mutations. - These data support transient MutL inhibition as a practical genome-engineering strategy with relatively low off-target burden in P. putida.	Aparicio et al., 2020, Environmental Microbiology, Nov 2020, https://doi.org/10.1111/1462-2920.14814 (aparicio2020mismatchrepairhierarchy pages 8-9)

Table: This table summarizes the most relevant functional annotation evidence for Pseudomonas putida KT2440 MutL, including pathway role, inferred activities, mismatch-recognition behavior, and engineering phenotypes. It is useful for distinguishing organism-specific findings from broader bacterial MutL inferences.

13. Key primary sources (publication date and URL)

Aparicio T. et al. (Nov 2020). Environmental Microbiology. “Mismatch repair hierarchy of Pseudomonas putida revealed by mutagenic ssDNA recombineering of the pyrF gene”. https://doi.org/10.1111/1462-2920.14814 (aparicio2020mismatchrepairhierarchy pages 1-2)
Fernández-Cabezón L. et al. (Apr 2021). ACS Synthetic Biology. “Spatiotemporal Manipulation of the Mismatch Repair System of Pseudomonas putida Accelerates Phenotype Emergence”. https://doi.org/10.1021/acssynbio.1c00031 (fernandezcabezon2021spatiotemporalmanipulationof pages 1-2)
Wozniak KJ, Simmons LA. (Feb 2022). Nature Reviews Microbiology. “Bacterial DNA excision repair pathways”. https://doi.org/10.1038/s41579-022-00694-0 (wozniak2022bacterialdnaexcision pages 10-11)
Collingwood BW. et al. (Nov 2024). Biomolecules. “Action-At-A-Distance in DNA Mismatch Repair: Mechanistic Insights and Models for How DNA and Repair Proteins Facilitate Long-Range Communication”. https://doi.org/10.3390/biom14111442 (collingwood2024actionatadistanceindna pages 4-6)

14. Figure evidence (from retrieved images)

Mutation frequencies and relative fold-changes for RifR and StrR under conditional mutator devices (Figure 3 crop). (fernandezcabezon2021spatiotemporalmanipulationof media 4d80bb01)
Ura+ mutation frequencies under conditional mutator devices (Figure 4a crop). (fernandezcabezon2021spatiotemporalmanipulationof media 1d27dc75)

References

(aparicio2020mismatchrepairhierarchy pages 2-3): Tomas Aparicio, Akos Nyerges, István Nagy, Csaba Pal, Esteban Martínez‐García, and Víctor de Lorenzo. Mismatch repair hierarchy of pseudomonas putida revealed by mutagenic ssdna recombineering of the pyrf gene. Environmental Microbiology, 22:45-58, Nov 2020. URL: https://doi.org/10.1111/1462-2920.14814, doi:10.1111/1462-2920.14814. This article has 23 citations and is from a domain leading peer-reviewed journal.
(aparicio2020mismatchrepairhierarchy pages 1-2): Tomas Aparicio, Akos Nyerges, István Nagy, Csaba Pal, Esteban Martínez‐García, and Víctor de Lorenzo. Mismatch repair hierarchy of pseudomonas putida revealed by mutagenic ssdna recombineering of the pyrf gene. Environmental Microbiology, 22:45-58, Nov 2020. URL: https://doi.org/10.1111/1462-2920.14814, doi:10.1111/1462-2920.14814. This article has 23 citations and is from a domain leading peer-reviewed journal.
(aparicio2020mismatchrepairhierarchy pages 3-5): Tomas Aparicio, Akos Nyerges, István Nagy, Csaba Pal, Esteban Martínez‐García, and Víctor de Lorenzo. Mismatch repair hierarchy of pseudomonas putida revealed by mutagenic ssdna recombineering of the pyrf gene. Environmental Microbiology, 22:45-58, Nov 2020. URL: https://doi.org/10.1111/1462-2920.14814, doi:10.1111/1462-2920.14814. This article has 23 citations and is from a domain leading peer-reviewed journal.
(fernandezcabezon2021spatiotemporalmanipulationof pages 4-5): Lorena Fernández-Cabezón, Antonin Cros, and Pablo I. Nikel. Spatiotemporal manipulation of the mismatch repair system of pseudomonas putida accelerates phenotype emergence. Apr 2021. URL: https://doi.org/10.1021/acssynbio.1c00031, doi:10.1021/acssynbio.1c00031. This article has 28 citations and is from a domain leading peer-reviewed journal.
(wozniak2022bacterialdnaexcision pages 10-11): Katherine J. Wozniak and Lyle A. Simmons. Bacterial dna excision repair pathways. Nature Reviews Microbiology, 20:465-477, Feb 2022. URL: https://doi.org/10.1038/s41579-022-00694-0, doi:10.1038/s41579-022-00694-0. This article has 102 citations and is from a highest quality peer-reviewed journal.
(wozniak2022bacterialdnaexcision pages 18-19): Katherine J. Wozniak and Lyle A. Simmons. Bacterial dna excision repair pathways. Nature Reviews Microbiology, 20:465-477, Feb 2022. URL: https://doi.org/10.1038/s41579-022-00694-0, doi:10.1038/s41579-022-00694-0. This article has 102 citations and is from a highest quality peer-reviewed journal.
(fernandezcabezon2021spatiotemporalmanipulationof pages 1-2): Lorena Fernández-Cabezón, Antonin Cros, and Pablo I. Nikel. Spatiotemporal manipulation of the mismatch repair system of pseudomonas putida accelerates phenotype emergence. Apr 2021. URL: https://doi.org/10.1021/acssynbio.1c00031, doi:10.1021/acssynbio.1c00031. This article has 28 citations and is from a domain leading peer-reviewed journal.
(aparicio2020mismatchrepairhierarchy pages 5-6): Tomas Aparicio, Akos Nyerges, István Nagy, Csaba Pal, Esteban Martínez‐García, and Víctor de Lorenzo. Mismatch repair hierarchy of pseudomonas putida revealed by mutagenic ssdna recombineering of the pyrf gene. Environmental Microbiology, 22:45-58, Nov 2020. URL: https://doi.org/10.1111/1462-2920.14814, doi:10.1111/1462-2920.14814. This article has 23 citations and is from a domain leading peer-reviewed journal.
(collingwood2024actionatadistanceindna pages 4-6): Bryce W. Collingwood, Scott J. Witte, and Carol M. Manhart. Action-at-a-distance in dna mismatch repair: mechanistic insights and models for how dna and repair proteins facilitate long-range communication. Biomolecules, 14:1442, Nov 2024. URL: https://doi.org/10.3390/biom14111442, doi:10.3390/biom14111442. This article has 1 citations.
(collingwood2024actionatadistanceindna pages 1-3): Bryce W. Collingwood, Scott J. Witte, and Carol M. Manhart. Action-at-a-distance in dna mismatch repair: mechanistic insights and models for how dna and repair proteins facilitate long-range communication. Biomolecules, 14:1442, Nov 2024. URL: https://doi.org/10.3390/biom14111442, doi:10.3390/biom14111442. This article has 1 citations.
(fernandezcabezon2021spatiotemporalmanipulationof media 4d80bb01): Lorena Fernández-Cabezón, Antonin Cros, and Pablo I. Nikel. Spatiotemporal manipulation of the mismatch repair system of pseudomonas putida accelerates phenotype emergence. Apr 2021. URL: https://doi.org/10.1021/acssynbio.1c00031, doi:10.1021/acssynbio.1c00031. This article has 28 citations and is from a domain leading peer-reviewed journal.
(fernandezcabezon2021spatiotemporalmanipulationof pages 5-6): Lorena Fernández-Cabezón, Antonin Cros, and Pablo I. Nikel. Spatiotemporal manipulation of the mismatch repair system of pseudomonas putida accelerates phenotype emergence. Apr 2021. URL: https://doi.org/10.1021/acssynbio.1c00031, doi:10.1021/acssynbio.1c00031. This article has 28 citations and is from a domain leading peer-reviewed journal.
(fernandezcabezon2021spatiotemporalmanipulationof media 1d27dc75): Lorena Fernández-Cabezón, Antonin Cros, and Pablo I. Nikel. Spatiotemporal manipulation of the mismatch repair system of pseudomonas putida accelerates phenotype emergence. Apr 2021. URL: https://doi.org/10.1021/acssynbio.1c00031, doi:10.1021/acssynbio.1c00031. This article has 28 citations and is from a domain leading peer-reviewed journal.
(aparicio2020mismatchrepairhierarchy pages 8-9): Tomas Aparicio, Akos Nyerges, István Nagy, Csaba Pal, Esteban Martínez‐García, and Víctor de Lorenzo. Mismatch repair hierarchy of pseudomonas putida revealed by mutagenic ssdna recombineering of the pyrf gene. Environmental Microbiology, 22:45-58, Nov 2020. URL: https://doi.org/10.1111/1462-2920.14814, doi:10.1111/1462-2920.14814. This article has 23 citations and is from a domain leading peer-reviewed journal.
(aparicio2020mismatchrepairhierarchy pages 12-13): Tomas Aparicio, Akos Nyerges, István Nagy, Csaba Pal, Esteban Martínez‐García, and Víctor de Lorenzo. Mismatch repair hierarchy of pseudomonas putida revealed by mutagenic ssdna recombineering of the pyrf gene. Environmental Microbiology, 22:45-58, Nov 2020. URL: https://doi.org/10.1111/1462-2920.14814, doi:10.1111/1462-2920.14814. This article has 23 citations and is from a domain leading peer-reviewed journal.
(aparicio2020mismatchrepairhierarchy pages 9-10): Tomas Aparicio, Akos Nyerges, István Nagy, Csaba Pal, Esteban Martínez‐García, and Víctor de Lorenzo. Mismatch repair hierarchy of pseudomonas putida revealed by mutagenic ssdna recombineering of the pyrf gene. Environmental Microbiology, 22:45-58, Nov 2020. URL: https://doi.org/10.1111/1462-2920.14814, doi:10.1111/1462-2920.14814. This article has 23 citations and is from a domain leading peer-reviewed journal.

Artifacts

Edison artifact artifact-00

Citations

fernandezcabezon2021spatiotemporalmanipulationof pages 1-2
aparicio2020mismatchrepairhierarchy pages 3-5
wozniak2022bacterialdnaexcision pages 10-11
fernandezcabezon2021spatiotemporalmanipulationof pages 5-6
aparicio2020mismatchrepairhierarchy pages 5-6
aparicio2020mismatchrepairhierarchy pages 8-9
collingwood2024actionatadistanceindna pages 4-6
aparicio2020mismatchrepairhierarchy pages 12-13
aparicio2020mismatchrepairhierarchy pages 1-2
aparicio2020mismatchrepairhierarchy pages 2-3
fernandezcabezon2021spatiotemporalmanipulationof pages 4-5
wozniak2022bacterialdnaexcision pages 18-19
collingwood2024actionatadistanceindna pages 1-3
aparicio2020mismatchrepairhierarchy pages 9-10
DQHA(X)2E(X)4E
https://doi.org/10.3390/biom14111442
https://doi.org/10.1038/s41579-022-00694-0
https://doi.org/10.1111/1462-2920.14814
https://doi.org/10.1021/acssynbio.1c00031
https://doi.org/10.1111/1462-2920.14814,
https://doi.org/10.1021/acssynbio.1c00031,
https://doi.org/10.1038/s41579-022-00694-0,
https://doi.org/10.3390/biom14111442,

📚 Additional Documentation

Notes

(mutL-notes.md)

mutL curation notes

KT2440 MutL (Q88DD1; PP_4896) is directly implicated by transient inhibition in
the P. putida mismatch-hierarchy study PMID:31599106. The reviewed UniProt sentence that
calls the pathway Dam-dependent is generic HAMAP text and conflicts with the
absence of MutH in KT2440; it was not propagated into the biological summary.

Mismatch-specific binding and ATP-dependent DNA damage sensor activity were
removed because MutS performs recognition. A new double-stranded DNA
endonuclease annotation is proposed by ISS from P. aeruginosa MutL Q9HUL8:
a reproducible global alignment contains 521 identical residues among 627
aligned residue pairs (83.0941%)
[file:PSEPK/mutL/mutL-bioinformatics/RESULTS.md "of which 521 are identical
(83.0941%)."], and Q9HUL8 directly nicks circular duplex DNA
PMID:23969026.
The transfer remains an inference until Q88DD1 is assayed.

Bioinformatics Results

(RESULTS.md)

MutL pairwise identity results

Result

The global protein alignment of Pseudomonas putida KT2440 MutL Q88DD1 and
Pseudomonas aeruginosa PAO1 MutL Q9HUL8 contains 627 aligned residue pairs, of
which 521 are identical (83.0941%). The alignment has 638 total columns because
of gap positions. Q88DD1 is 632 amino acids and Q9HUL8 is 633 amino acids.

These values come from results/mutl_pairwise_identity.tsv, generated with
Biopython 1.85 PairwiseAligner in global mode using match 2, mismatch -1,
gap-open -5, and gap-extension -0.5. The TSV records the input lengths and
SHA-256 sequence digests. The complete alignment is retained in
results/mutl_pairwise_alignment.txt.

The high full-length identity supports treating Q9HUL8 as a close sequence
ortholog for an ISS transfer. It does not by itself establish Q88DD1
endonuclease activity; the biochemical activity comes from PMID:23969026 and
still requires direct testing in KT2440.

Independent script test

The same parameterized script completed on P. putida UvrD Q88C31 and E. coli
UvrD P03018. results/uvrd_smoke_test.tsv reports 457 identical residues among
719 aligned residue pairs (63.5605%), with the alignment retained separately.
This test checks that the script accepts a different protein pair and does not
depend on hardcoded MutL sequences or result values.

Reproducibility checklist

[x] Scripts take all accessions, inputs, outputs, and alignment scores as parameters.
[x] Canonical UniProtKB FASTA inputs are retained under data/.
[x] Input sequence lengths and SHA-256 digests are recorded in result TSVs.
[x] Biopython is pinned to version 1.85 in pyproject.toml and uv.lock.
[x] The complete MutL analysis completed as expected.
[x] Direct TSV and alignment outputs are retained under results/.
[x] The alignment script was tested on a different protein pair.
[x] just --justfile genes/PSEPK/mutL/mutL-bioinformatics/justfile all reruns the workflow.

📄 View Raw YAML

id: Q88DD1
gene_symbol: mutL
product_type: PROTEIN
status: DRAFT
taxon:
  id: NCBITaxon:160488
  label: Pseudomonas putida (strain ATCC 47054 / DSM 6125 / CFBP 8728 / NCIMB 11950 / KT2440)
description: >-
  MutL is the ATP-dependent coordinator and inferred strand-incision
  endonuclease of the MutH-independent mismatch repair pathway. It is recruited
  after MutS recognizes a replication mismatch, uses its N-terminal GHKL
  ATPase cycle to organize repair, and dimerizes through a C-terminal domain
  that is strongly inferred to nick duplex DNA. KT2440 lacks MutH, placing
  MutL-mediated incision in a methylation-independent repair architecture.
existing_annotations:
  - term:
      id: GO:0005524
      label: ATP binding
    evidence_type: IEA
    original_reference_id: GO_REF:0000002
    qualifier: enables
    review:
      summary: >-
        Retain as non-core. ATP binding supports the MutL conformational cycle,
        while ATP hydrolysis is the more informative catalytic function.
      action: KEEP_AS_NON_CORE
      reason: Correct property of the N-terminal GHKL ATPase domain.
  - term:
      id: GO:0006259
      label: DNA metabolic process
    evidence_type: IEA
    original_reference_id: GO_REF:0000117
    qualifier: involved_in
    review:
      summary: This broad parent process adds no information beyond mismatch repair.
      action: MARK_AS_OVER_ANNOTATED
      reason: GO:0006298 is the direct pathway term.
  - term:
      id: GO:0006298
      label: mismatch repair
    evidence_type: IEA
    original_reference_id: GO_REF:0000120
    qualifier: involved_in
    review:
      summary: >-
        Accept. Transient loss of MutL activity was used directly to expose the
        mismatch-correction hierarchy in KT2440.
      action: ACCEPT
      reason: Core process with direct P. putida genetic support.
      supported_by:
        - reference_id: PMID:31599106
          supporting_text: "permanent deletion of mutS or transient loss of mutL activity"
  - term:
      id: GO:0016887
      label: ATP hydrolysis activity
    evidence_type: IEA
    original_reference_id: GO_REF:0000120
    qualifier: enables
    review:
      summary: Accept as the catalytic function of the conserved GHKL ATPase domain.
      action: ACCEPT
      reason: >-
        Pseudomonas MutL ATPase-site mutations cause defective mismatch repair,
        and Q88DD1 retains the conserved domain.
      supported_by:
        - reference_id: PMID:11952911
          supporting_text: "residue known to be essential for its ATPase activity."
  - term:
      id: GO:0030983
      label: mismatched DNA binding
    evidence_type: IEA
    original_reference_id: GO_REF:0000002
    qualifier: enables
    review:
      summary: >-
        Remove. MutL can bind DNA in the repair complex, but mismatch-specific
        recognition is the role of MutS; direct mismatch specificity is not
        established for MutL.
      action: REMOVE
      reason: InterPro propagation conflates recruitment to mismatch-bound MutS with mismatch sensing.
  - term:
      id: GO:0032300
      label: mismatch repair complex
    evidence_type: IEA
    original_reference_id: GO_REF:0000120
    qualifier: part_of
    review:
      summary: Accept. MutL is a defining component recruited by mismatch-bound MutS.
      action: ACCEPT
      reason: Correct complex membership without assigning MutS's recognition function to MutL.
  - term:
      id: GO:0140664
      label: ATP-dependent DNA damage sensor activity
    evidence_type: IEA
    original_reference_id: GO_REF:0000002
    qualifier: enables
    review:
      summary: >-
        Remove. MutL is an ATP-dependent coordinator and endonuclease recruited
        by MutS, not the protein that initially senses the mismatch.
      action: REMOVE
      reason: The sensor term belongs to MutS in this pathway.
  - term:
      id: GO:1990238
      label: double-stranded DNA endonuclease activity
    evidence_type: ISS
    original_reference_id: PMID:23969026
    qualifier: enables
    review:
      summary: >-
        Add by close-ortholog inference. Pseudomonas aeruginosa MutL directly
        nicks duplex plasmid DNA, and a reproducible global alignment finds 521
        identical residues among 627 aligned residue pairs (83.1%) between its
        reviewed protein Q9HUL8 and KT2440 Q88DD1.
      action: NEW
      reason: >-
        The direct biochemical exemplar is a close Pseudomonas ortholog with
        the same MutH-independent architecture; a direct Q88DD1 assay is still
        needed.
      additional_reference_ids:
        - UniProtKB:Q9HUL8
      supported_by:
        - reference_id: PMID:23969026
          supporting_text: "PaMutL was able to nick covalently closed circular plasmids"
        - reference_id: file:PSEPK/mutL/mutL-bioinformatics/RESULTS.md
          supporting_text: "of which 521 are identical (83.0941%)."
references:
  - id: GO_REF:0000002
    title: Gene Ontology annotation through association of InterPro records with GO terms
    findings: []
  - id: GO_REF:0000117
    title: Electronic Gene Ontology annotations created by ARBA machine learning models
    findings: []
  - id: GO_REF:0000120
    title: Combined Automated Annotation using Multiple IEA Methods
    findings: []
  - id: file:PSEPK/mutL/mutL-uniprot.txt
    title: UniProtKB entry for PSEPK MutL (Q88DD1)
    findings:
      - supporting_text: "This protein is involved in the repair of mismatches in DNA."
      - supporting_text: "required for dam-dependent methyl-directed DNA mismatch repair"
  - id: PMID:31599106
    title: Mismatch repair hierarchy of Pseudomonas putida revealed by mutagenic ssDNA recombineering of the pyrF gene.
    findings:
      - supporting_text: "permanent deletion of mutS or transient loss of mutL activity"
        reference_section_type: ABSTRACT
    reference_review:
      relevance: HIGH
      correctness: VERIFIED
      review_notes: >-
        PubMed and the cached abstract were checked. The study directly tests
        transient MutL inhibition in KT2440.
  - id: PMID:11952911
    title: "The mismatch repair system (mutS, mutL and uvrD genes) in Pseudomonas aeruginosa: molecular characterization of naturally occurring mutants."
    findings:
      - supporting_text: "residue known to be essential for its ATPase activity."
        reference_section_type: ABSTRACT
    reference_review:
      relevance: MEDIUM
      correctness: VERIFIED
      review_notes: >-
        PubMed was checked. This close-species genetic study supports the
        functional importance of the conserved Pseudomonas MutL ATPase site.
  - id: PMID:23969026
    title: Analysis of DNA structure and sequence requirements for Pseudomonas aeruginosa MutL endonuclease activity.
    findings:
      - supporting_text: "devoid of MutH is the presence of a MutL homologue with endonuclease activity."
        reference_section_type: ABSTRACT
      - supporting_text: "PaMutL was able to nick covalently closed circular plasmids"
        reference_section_type: ABSTRACT
    reference_review:
      relevance: HIGH
      correctness: VERIFIED
      review_notes: >-
        PubMed was checked. This is direct biochemical evidence for
        double-stranded DNA nicking by P. aeruginosa MutL Q9HUL8. Its close
        sequence relationship to Q88DD1 is documented by the reproducible
        local alignment; transfer to Q88DD1 is explicitly ISS.
  - id: PMID:23922851
    title: Analysis of the interaction interfaces of the N-terminal domain from Pseudomonas aeruginosa MutL.
    findings:
      - supporting_text: "C-terminal (CTD) dimerization domain that possesses metal ion-dependent endonuclease activity."
        reference_section_type: ABSTRACT
    reference_review:
      relevance: MEDIUM
      correctness: VERIFIED
      review_notes: >-
        PubMed and cached full text were checked. The study supports the
        ATPase/endonuclease domain architecture of the close Pseudomonas
        exemplar.
  - id: UniProtKB:Q9HUL8
    title: UniProtKB entry for Pseudomonas aeruginosa PAO1 MutL
    findings: []
  - id: file:PSEPK/mutL/mutL-bioinformatics/RESULTS.md
    title: Reproducible Q88DD1-Q9HUL8 MutL global protein alignment
    findings:
      - statement: >-
          The alignment contains 521 identical residues among 627 aligned
          residue pairs, or 83.0941% identity.
        supporting_text: "of which 521 are identical (83.0941%)."
    reference_review:
      relevance: HIGH
      correctness: VERIFIED
      review_notes: >-
        Input FASTA records, SHA-256 digests, scoring parameters, scripts,
        complete alignment, direct TSV output, and an independent UvrD script
        test are retained under mutL-bioinformatics.
core_functions:
  - description: >-
      MutL hydrolyzes ATP to coordinate assembly and progression of the
      MutS-initiated mismatch repair reaction.
    molecular_function:
      id: GO:0016887
      label: ATP hydrolysis activity
    directly_involved_in:
      - id: GO:0006298
        label: mismatch repair
    in_complex:
      id: GO:0032300
      label: mismatch repair complex
    supported_by:
      - reference_id: PMID:31599106
        supporting_text: "permanent deletion of mutS or transient loss of mutL activity"
      - reference_id: PMID:11952911
        supporting_text: "residue known to be essential for its ATPase activity."
  - description: >-
      Q88DD1 is inferred from the close P. aeruginosa ortholog to nick duplex
      DNA and provide the strand-incision activity required by a
      MutH-independent mismatch repair pathway.
    molecular_function:
      id: GO:1990238
      label: double-stranded DNA endonuclease activity
    directly_involved_in:
      - id: GO:0006298
        label: mismatch repair
    in_complex:
      id: GO:0032300
      label: mismatch repair complex
    supported_by:
      - reference_id: PMID:23969026
        supporting_text: "PaMutL was able to nick covalently closed circular plasmids"
      - reference_id: file:PSEPK/mutL/mutL-bioinformatics/RESULTS.md
        supporting_text: "of which 521 are identical (83.0941%)."
proposed_new_terms: []
suggested_questions:
  - question: >-
      Does Q88DD1 nick the nascent strand directly, and is its activity oriented
      or stimulated by the KT2440 beta clamp?
suggested_experiments:
  - hypothesis: Q88DD1 is the strand-incision endonuclease of KT2440 MMR.
    description: >-
      Purify Q88DD1 and test metal-dependent nicking of covalently closed
      duplex DNA with MutS, mismatch-containing substrates, ATP/ADP, and the
      KT2440 beta clamp; compare catalytic-site and clamp-binding mutants.
    experiment_type: reconstituted MutH-independent mismatch incision assay

mutL

Gene Description

Existing Annotations Review

Core Functions

MutL hydrolyzes ATP to coordinate assembly and progression of the MutS-initiated mismatch repair reaction.

Q88DD1 is inferred from the close P. aeruginosa ortholog to nick duplex DNA and provide the strand-incision activity required by a MutH-independent mismatch repair pathway.

References

Suggested Questions for Experts

Suggested Experiments

Deep Research

Falcon

Research Report: Pseudomonas putida KT2440 mutL (PP_4896; UniProt Q88DD1) — Functional Annotation and Evidence

0. Executive summary

1. Mandatory verification: correct gene/protein identity

1.1 Mapping UniProt context to primary literature

1.2 Avoiding ambiguity with the symbol “mutL”

2. Key concepts and definitions (current understanding)

2.1 DNA mismatch repair (MMR)

2.2 Canonical players and pathway architectures

3. MutL (PP_4896) molecular function and mechanism

3.1 Primary biological role in P. putida KT2440

3.2 Interaction partners and pathway placement

3.3 Enzymatic activities: what is known vs inferred

3.3.1 Evidence-supported inferences for MutH-less systems

3.3.2 ATPase/clamp behaviors and “action-at-a-distance” models (recent mechanistic synthesis)

4. Cellular localization: where MutL acts

5. P. putida KT2440-specific functional phenotypes and quantitative data

5.1 Dominant-negative mutL E36K as a conditional mutator system

5.1.1 Concept and construction

5.1.2 Mutation-frequency increases and selectable phenotypes

5.1.3 Statistics for auxotrophy reversion

5.2 Mismatch recognition hierarchy in P. putida MMR (functional “specificity”)

5.3 Genome engineering application and off-target burden

6. Recent developments (prioritizing 2023–2024)

7. Current applications and real-world implementations

7.1 Adaptive laboratory evolution (ALE) and phenotype emergence

7.2 Genome editing and recombineering

8. Expert opinions and analysis (authoritative interpretations)

9. Data highlights (recent statistics and quantitative results)

10. Evidence-based functional annotation (proposed)

10.1 Molecular function (GO-style narrative)

10.2 Reaction/biochemical activity and substrate specificity

10.3 Cellular localization

11. Limitations and evidence gaps

12. Summary table

13. Key primary sources (publication date and URL)

14. Figure evidence (from retrieved images)

Artifacts

Citations

📚 Additional Documentation

Notes

mutL curation notes

Bioinformatics Results

MutL pairwise identity results

Result

Independent script test

Reproducibility checklist

📄 View Raw YAML