| Claim/Concept | Evidence summary | Organism/system (KT2440 vs other) | Quantitative data (if any) | Primary source (first author year, journal) | Publication date (month/year) | URL |
|---|---|---|---|---|---|---|
| PP_0634 maps to pilA in *Pseudomonas putida* KT2440 | Comparative mapping of adherence/type IV pili genes lists *P. aeruginosa* **pilA** (PA4525) corresponding to *P. putida* KT2440 **PP_0634**, supporting that UniProt Q88Q62/PP_0634 is the KT2440 **pilA** ortholog (pqac-00000001). | KT2440 | None reported | Udaondo 2025, *Int. J. Mol. Sci.* | 05/2025 | https://doi.org/10.3390/ijms26104677 |
| KT2440 PilA is a type IVa pilin-family protein | A sequence survey of type IVa pilins includes a *P. putida* KT2440 entry (NP_742795) among “other bacteria with type IVa pilin genes”; the KT2440 sequence carries the conserved C-terminal disulfide-bonded loop features typical of type IVa pilins (pqac-00000000). | KT2440 | DSL sequence listed as **CTTDIEDDLAPKGC** (pqac-00000000) | Harvey 2009, *J. Bacteriol.* | 11/2009 | https://doi.org/10.1128/jb.00943-09 |
| PilA is the major pilin subunit of type IV pili | Reviews define PilA as the major pilin/prepilin whose polymerization forms the type IVa pilus fiber; thousands of PilA-like subunits can build a filament (pqac-00000002, pqac-00000005, pqac-00000006). | Other *Pseudomonas* / general T4P biology | None specific | McCallum 2019, *Microbiol. Spectrum* | 04/2019 | https://doi.org/10.1128/microbiolspec.psib-0006-2018 |
| PilA precursor processing requires prepilin peptidase PilD and includes N-terminal methylation | Authoritative reviews and primary studies state that PilA is synthesized as a prepilin with an N-terminal leader peptide that is cleaved by **PilD**; PilD is bifunctional and methylates the nascent N terminus. Cleavage is essential for pilus biogenesis, whereas methylation is conserved and in some systems not strictly required for assembly (pqac-00000003, pqac-00000004, pqac-00000005, pqac-00000015, pqac-00000016). | Other *Pseudomonas* / general T4P biology | Prepilin hydrophobic stretch typically **20–25 aa** (pqac-00000004) | Kuchma 2022, *J. Bacteriol.* | 10/2022 | https://doi.org/10.1128/jb.00186-22 |
| Direct *P. putida* evidence linking PilD to PilA processing/methylation | In *P. putida* GB-1, **xcpA/pilD** is described as a leader peptidase (prepilin peptidase) required for processing and methylation of the PilA prepilin; the paper also notes that KT2440 contains related Xcp/Gsp-like clusters, supporting the presence of cognate maturation machinery in *P. putida* genomes (pqac-00000013, pqac-00000017). | *P. putida* GB-1 with mention of KT2440 gene clusters | None reported | De Vrind 2003, *Mol. Microbiol.* | 02/2003 | https://doi.org/10.1046/j.1365-2958.2003.03339.x |
| Localization and architecture of the T4P machine relevant to PilA function | Pilins are stored in the **inner membrane** before assembly; assembled pili extend through the **outer-membrane secretin PilQ**. The motor/platform subcomplex includes **PilC** with ATPases **PilB** (extension) and **PilT/PilU** (retraction), while PilMNOP stabilizes the envelope-spanning apparatus (pqac-00000002, pqac-00000003, pqac-00000008, pqac-00000018). | Other *Pseudomonas* / general T4P biology | Pilus diameter about **6 nm** and can extend **tens of microns** (pqac-00000008) | Talà 2022, dissertation | 01/2022 | https://doi.org/10.5075/epfl-thesis-8646 |
| Structural organization of PilA in the filament | PilA has a long N-terminal α-helix and C-terminal globular domain; in assembled pili the α1N helices pack into a hydrophobic core, while the αβ-loop/D-loop are surface exposed and variable, consistent with extracellular interaction roles (pqac-00000002, pqac-00000005). | Other *Pseudomonas* / general T4P biology | Helical rise about **10 Å**; twist about **80–100°** (pqac-00000002) | McCallum 2019, *Microbiol. Spectrum* | 04/2019 | https://doi.org/10.1128/microbiolspec.psib-0006-2018 |
| Biophysical output of T4P retraction | T4P retraction is ATP-driven and can generate very large forces; classic and modern measurements summarized in review literature report single-pilus forces up to about **80 pN**, supporting roles in twitching motility, surface engagement, and mechanosensing (pqac-00000009). | General T4P biology | Force up to **~80 pN** (pqac-00000009) | Singh 2022, *MMBR* | 09/2022 | https://doi.org/10.1128/mmbr.00076-22 |
| Functional pathway context of PilA | T4P systems support twitching motility, adhesion, biofilm formation, DNA uptake/natural competence, and surface sensing; in *P. aeruginosa*, PilT-driven retraction is required for robust surface-induced cAMP signaling, illustrating how PilA-containing pili connect mechanics to signaling (pqac-00000003, pqac-00000006, pqac-00000007, pqac-00000009). | Other *Pseudomonas* / general T4P biology | Intracellular spread speed reported for WT *P. aeruginosa* cytosolic twitching **>0.05 μm s−1** in one study (pqac-00000003 cites broader pathway context; speed from pqac-00000003-linked paper summary in search results was not used here for KT2440 annotation) | Kuchma 2022, *J. Bacteriol.* | 10/2022 | https://doi.org/10.1128/jb.00186-22 |
| Evidence limit for KT2440-specific phenotypes | Available evidence directly verifies **identity/family assignment** of PP_0634 as KT2440 PilA, but the gathered sources did **not** provide a KT2440-specific pilA mutant phenotype for twitching, adhesion, biofilm, or competence; these functions are therefore best treated as family-based inference unless future KT2440 experiments are found (pqac-00000001, pqac-00000000). | KT2440 | None | Udaondo 2025, *Int. J. Mol. Sci.*; Harvey 2009, *J. Bacteriol.* | 05/2025; 11/2009 | https://doi.org/10.3390/ijms26104677 ; https://doi.org/10.1128/jb.00943-09 |
| Applied implementation: engineering pili-related functions for fermentation | A 2024 applied study engineered *P. putida* PCL1760 by deleting **algA, flhA, and pilQ** (not pilA) to reduce motility/biofilm. This shows real-world value of targeting T4P biogenesis for industrial strain optimization, though it is not direct evidence on KT2440 PilA itself (pqac-00000011, pqac-00000012). | *P. putida* PCL1760 (not KT2440) | Biofilm **40% lower after 72 h**; rich medium **1.39×10^10 vs 6.4×10^9 CFU/mL** mutant vs WT; mineral medium **6.11×10^9 vs 1.36×10^9 CFU/mL** mutant vs WT (pqac-00000011, pqac-00000012) | Frolov 2024, *Fermentation* | 11/2024 | https://doi.org/10.3390/fermentation10120606 |
| Energetic rationale for appendage engineering | The same applied study cites energetic costs of motility appendages, helping explain why disabling flagellar/pilus systems can improve bioreactor growth; this provides context for why PilA/T4P-related systems matter in biotechnology (pqac-00000012). | *P. putida* PCL1760 / broader *Pseudomonas* context | Flagellar biosynthesis about **2%** of biosynthetic resources; rotation about **0.1%** of cell energy (pqac-00000012) | Frolov 2024, *Fermentation* | 11/2024 | https://doi.org/10.3390/fermentation10120606 |


*Table: This table compiles direct KT2440-specific evidence for PP_0634 as pilA together with carefully labeled family-level type IV pilus biology needed for functional annotation. It also includes an applied Pseudomonas implementation example showing why pili-related systems matter in biotechnology.*