fliA

UniProt ID: Q88EW1
Organism: Pseudomonas putida (strain ATCC 47054 / DSM 6125 / CFBP 8728 / NCIMB 11950 / KT2440)
Review Status: DRAFT
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Gene Description

fliA encodes the flagellar alternative sigma factor Sigma-28 in Pseudomonas putida KT2440. It confers promoter specificity on RNA polymerase for flagella-related genes, so its core biological role is sigma factor activity and transcription initiation rather than RNA polymerase catalytic activity.

Existing Annotations Review

GO Term Evidence Action Reason
GO:0003677 DNA binding
IEA
GO_REF:0000120
MARK AS OVER ANNOTATED
Summary: DNA binding is not entirely wrong for a sigma factor-containing holoenzyme, but it is too generic as a standalone description of FliA. The precise molecular function is sigma factor activity.
Reason: GO:0016987 captures promoter-specific sigma-factor function better than generic DNA binding.
Supporting Evidence:
file:PSEPK/fliA/fliA-uniprot.txt
RNA polymerase sigma factor FliA
file:PSEPK/fliA/fliA-goa.tsv
GO:0003677 DNA binding
file:PSEPK/fliA/fliA-deep-research-falcon.md
In KT2440, FliA’s **primary molecular function** is to function as an **RNAP sigma factor** that recognizes **Οƒ28-type promoters** to activate late flagellar/chemotaxis transcription.
GO:0003700 DNA-binding transcription factor activity
IEA
GO_REF:0000002
MODIFY
Summary: FliA is a transcription regulatory factor, but the generic DNA-binding transcription factor term is less precise than sigma factor activity for a bacterial RNA polymerase sigma subunit.
Reason: Replace the broad transcription-factor term with the specific sigma factor molecular function.
Proposed replacements: sigma factor activity
Supporting Evidence:
file:PSEPK/fliA/fliA-uniprot.txt
RNA polymerase sigma factor FliA
file:PSEPK/fliA/fliA-uniprot.txt
Belongs to the sigma-70 factor family. FliA subfamily.
file:PSEPK/fliA/fliA-deep-research-falcon.md
**FliA is an alternative sigma factor** that binds core RNA polymerase (RNAP) to alter promoter recognition specificity. In *P. putida* KT2440, this is explicitly described as FliA β€œconferr[ing] promoter-recognition specificity to core RNA polymerase (RNAP),” consistent with sigma-factor biology.
GO:0003899 DNA-directed RNA polymerase activity
IEA
GO_REF:0000002
REMOVE
Summary: This annotation should be removed. FliA is a sigma factor that helps RNA polymerase initiate at flagellar promoters; it is not the catalytic RNA polymerase enzyme.
Reason: RNA polymerase catalytic activity belongs to the core polymerase complex, whereas FliA provides promoter specificity.
Supporting Evidence:
file:PSEPK/fliA/fliA-uniprot.txt
Sigma factors are initiation factors that promote the
file:PSEPK/fliA/fliA-goa.tsv
GO:0003899 DNA-directed RNA polymerase activity
file:PSEPK/fliA/fliA-deep-research-falcon.md
**FliA is an alternative sigma factor** that binds core RNA polymerase (RNAP) to alter promoter recognition specificity. In *P. putida* KT2440, this is explicitly described as FliA β€œconferr[ing] promoter-recognition specificity to core RNA polymerase (RNAP),” consistent with sigma-factor biology.
GO:0005737 cytoplasm
IEA
GO_REF:0000120
ACCEPT
Summary: This location annotation is appropriate for a bacterial sigma factor that associates with cytoplasmic RNA polymerase.
Reason: UniProt places FliA in the cytoplasm.
Supporting Evidence:
file:PSEPK/fliA/fliA-uniprot.txt
SUBCELLULAR LOCATION: Cytoplasm
file:PSEPK/fliA/fliA-goa.tsv
GO:0005737 cytoplasm
file:PSEPK/fliA/fliA-deep-research-falcon.md
FliA is not a secreted or membrane-embedded protein; it functions by **associating with cytosolic RNAP** and acting at **chromosomal promoters**. KT2440 literature describes FliA as conferring promoter specificity to core RNAP, implying its functional localization is the cytosol/nucleoid region where RNAP-DNA transcription occurs.
GO:0006352 DNA-templated transcription initiation
IEA
GO_REF:0000120
ACCEPT
Summary: This is a core process annotation. Sigma factors act at transcription initiation by directing RNA polymerase to specific promoters.
Reason: FliA controls initiation at flagella-related promoters.
Supporting Evidence:
file:PSEPK/fliA/fliA-uniprot.txt
Sigma factors are initiation factors that promote the
file:PSEPK/fliA/fliA-goa.tsv
GO:0006352 DNA-templated transcription initiation
file:PSEPK/fliA/fliA-deep-research-falcon.md
In KT2440, FliA’s **primary molecular function** is to function as an **RNAP sigma factor** that recognizes **Οƒ28-type promoters** to activate late flagellar/chemotaxis transcription.
GO:0006355 regulation of DNA-templated transcription
IEA
GO_REF:0000120
MODIFY
Summary: This broad transcription-regulation term is directionally correct but less informative than the initiation-specific process term already present.
Reason: GO:2000142 is already present and ACCEPTED in this review; this MODIFY means the broad parent term should be dropped in favor of the existing initiation-specific term.
Supporting Evidence:
file:PSEPK/fliA/fliA-uniprot.txt
controls the expression of flagella-related genes
file:PSEPK/fliA/fliA-goa.tsv
GO:0006355 regulation of DNA-templated transcription
file:PSEPK/fliA/fliA-deep-research-falcon.md
In KT2440, FliA’s **primary molecular function** is to function as an **RNAP sigma factor** that recognizes **Οƒ28-type promoters** to activate late flagellar/chemotaxis transcription.
GO:0010468 regulation of gene expression
IEA
GO_REF:0000104
MODIFY
Summary: Regulation of gene expression is too broad for FliA. The direct process is regulation of transcription initiation through sigma-factor promoter recognition.
Reason: GO:2000142 is already present and ACCEPTED in this review; this MODIFY removes a redundant high-level gene-expression parent in favor of the existing initiation-specific term.
Supporting Evidence:
file:PSEPK/fliA/fliA-uniprot.txt
controls the expression of flagella-related genes
file:PSEPK/fliA/fliA-goa.tsv
GO:0010468 regulation of gene expression
file:PSEPK/fliA/fliA-deep-research-falcon.md
In KT2440, FliA’s **primary molecular function** is to function as an **RNAP sigma factor** that recognizes **Οƒ28-type promoters** to activate late flagellar/chemotaxis transcription.
GO:0016987 sigma factor activity
IEA
GO_REF:0000120
ACCEPT
Summary: This is the correct core molecular function for FliA. The protein is explicitly annotated as an RNA polymerase sigma factor and a sigma-70 family FliA subfamily member.
Reason: Sigma factor activity captures FliA promoter-specificity function.
Supporting Evidence:
file:PSEPK/fliA/fliA-uniprot.txt
RecName: Full=RNA polymerase sigma factor FliA
file:PSEPK/fliA/fliA-uniprot.txt
Belongs to the sigma-70 factor family. FliA subfamily.
file:PSEPK/fliA/fliA-goa.tsv
GO:0016987 sigma factor activity
file:PSEPK/fliA/fliA-deep-research-falcon.md
**FliA is an alternative sigma factor** that binds core RNA polymerase (RNAP) to alter promoter recognition specificity. In *P. putida* KT2440, this is explicitly described as FliA β€œconferr[ing] promoter-recognition specificity to core RNA polymerase (RNAP),” consistent with sigma-factor biology.
GO:2000142 regulation of DNA-templated transcription initiation
IEA
GO_REF:0000108
ACCEPT
Summary: This is the best specific regulatory process term in the current annotation set. FliA regulates transcription at initiation by directing RNA polymerase to flagellar promoters.
Reason: The logical inference from sigma factor activity to regulation of transcription initiation is biologically appropriate.
Supporting Evidence:
file:PSEPK/fliA/fliA-uniprot.txt
Sigma factors are initiation factors that promote the
file:PSEPK/fliA/fliA-goa.tsv
GO:2000142 regulation of DNA-templated transcription initiation
file:PSEPK/fliA/fliA-deep-research-falcon.md
In KT2440, FliA’s **primary molecular function** is to function as an **RNAP sigma factor** that recognizes **Οƒ28-type promoters** to activate late flagellar/chemotaxis transcription.
GO:0044780 bacterial-type flagellum assembly
IEA NEW
Summary: As the Class III (late-tier) flagellar sigma factor, FliA directs transcription of the genes that build the flagellar filament, a stator complex, and the chemotaxis apparatus, so it is functionally involved in completing bacterial-type flagellum assembly. This process is absent from the current IEA-only annotation set but is well supported by KT2440 primary literature summarized in the falcon deep research.
Reason: KT2440 primary literature places FliA at the late tier of the flagellar cascade, where its transcriptional output completes filament, stator, and chemotaxis biogenesis; this flagellum-assembly process role complements the molecular sigma factor function and is not captured by the existing transcription-centric terms.
Supporting Evidence:
file:PSEPK/fliA/fliA-deep-research-falcon.md
**Class III:** **FliA-dependent** transcription enables synthesis of the **filament**, at least one **stator** complex, and completion of the **chemotaxis apparatus**.
file:PSEPK/fliA/fliA-deep-research-falcon.md
In KT2440 the late output of FliA activity is explicitly described: **filament synthesis**, activation of at least one **stator complex**, and completion of the **chemotaxis apparatus**.

Core Functions

FliA is the Sigma-28 flagellar sigma factor that gives RNA polymerase promoter specificity for flagella-related genes and thereby controls transcription initiation.

Supporting Evidence:
  • file:PSEPK/fliA/fliA-uniprot.txt
    RecName: Full=RNA polymerase sigma factor FliA
  • file:PSEPK/fliA/fliA-uniprot.txt
    Sigma factors are initiation factors that promote the
  • file:PSEPK/fliA/fliA-uniprot.txt
    controls the expression of flagella-related genes
  • file:PSEPK/fliA/fliA-deep-research-falcon.md
    In KT2440, FliA’s **primary molecular function** is to function as an **RNAP sigma factor** that recognizes **Οƒ28-type promoters** to activate late flagellar/chemotaxis transcription.

As the Class III (late-tier) sigma factor in the KT2440 flagellar transcriptional cascade, FliA directs transcription of genes required for flagellar filament synthesis, stator assembly, and chemotaxis, thereby positively driving bacterial-type flagellum biogenesis. Its activity is gated post-translationally by the anti-sigma factor FlgM, which is exported via the flagellar type III secretion system upon hook-basal body completion.

Molecular Function:
sigma factor activity
Cellular Locations:
Supporting Evidence:
  • file:PSEPK/fliA/fliA-deep-research-falcon.md
    In KT2440 the late output of FliA activity is explicitly described: **filament synthesis**, activation of at least one **stator complex**, and completion of the **chemotaxis apparatus**.
  • file:PSEPK/fliA/fliA-deep-research-falcon.md
    FliA is regulated by the **anti-sigma factor FlgM**, which sequesters FliA until flagellar assembly reaches a checkpoint. In *P. putida*, the β€œfinal tier” is triggered when FliA is **released from inactivation by FlgM**, after **FlgM secretion via the flagellar type III secretion system (FT3SS)** upon hook completion.

References

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Suggested Questions for Experts

Q: Which KT2440 flagellar promoters are directly FliA-dependent rather than indirectly affected by the broader flagellar hierarchy?

Suggested Experiments

Experiment: Compare RNA-seq and promoter-reporter activity in wild-type, fliA deletion, and complemented strains during flagellar gene induction.

Hypothesis: FliA directly activates a defined late flagellar promoter set in KT2440.

Type: transcriptomics and promoter reporter analysis

Deep Research

Falcon

(fliA-deep-research-falcon.md)

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πŸ“š Additional Documentation

Notes

(fliA-notes.md)

fliA review notes

Description cleanup note

The YAML description field was revised to keep it as a standalone biological summary. Project-specific curation framing moved here instead.

  • Moved out of the YAML description: curation should emphasize sigma factor activity and transcription initiation rather than RNA polymerase catalytic activity.

πŸ“„ View Raw YAML

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