Type IV Pilus Alignment Subcomplex Proteins PilN and PilO Form Homo- and Heterodimers in Vivo
Bibliographic record
Abstract
Pseudomonas aeruginosa is a leading cause of hospital-acquired infections and is resistant to many antibiotics. Type IV pili (T4P) are among the key virulence factors used by P. aeruginosa for host cell attachment, biofilm formation, and twitching motility, making this system a promising target for novel therapeutics. Point mutations in the conserved PilMNOP alignment subcomplex were previously shown to have distinct effects on assembly and disassembly of T4P, suggesting that it may function in a dynamic manner. We introduced mutations encoding Cys substitutions into pilN and/or pilO on the chromosome to maintain normal stoichiometry and expression levels and captured covalent PilNO heterodimers, as well as PilN and PilO homodimers, in vivo Most covalent PilN or PilO homodimers had minimal functional impact in P. aeruginosa, suggesting that homodimers are a physiologically relevant state. However, certain covalent homo- or heterodimers eliminated twitching motility, suggesting that specific PilNO configurations are essential for T4P function. These data were verified using soluble N-terminal truncated fragments of PilN and PilO Cys mutants, which purified as a mixture of homo- and heterodimers at volumes consistent with a tetramer. Deletion of genes encoding alignment subcomplex components, PilM or PilP, but not other T4P components, including the motor ATPases PilB or PilT, blocked in vivo formation of disulfide-bonded PilNO heterodimers, suggesting that both PilM and PilP influence the heterodimer interface. Combined, our data suggest that T4P function depends on rearrangements at PilN and PilO interfaces.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".