<scp><i>Helicobacter pylori</i> FlgN</scp> binds its substrate <scp>FlgK</scp> and the flagellum <scp>ATPase FliI</scp> in a similar manner observed for the <scp>FliT</scp> chaperone
Bibliographic record
Abstract
Abstract In bacterial flagellum biogenesis, secretion of the hook–filament junction proteins FlgK and FlgL and completion of the flagellum requires the FlgN chaperone. Similarly, the related FliT chaperone is necessary for the secretion of the filament cap protein FliD and binds the flagellar export gate protein FlhA and the flagellum ATPase FliI. FlgN and FliT require FliJ for effective substrate secretion. In Helicobacter pylori, neither FlgN, FliT, nor FliJ have been annotated. We demonstrate that the genome location of HP1120 is identical to that of flgN in other flagellated bacteria and that HP1120 is the homolog of Campylobacter jejuni FlgN. A modeled HP1120 structure contains three α‐helices and resembles the FliT chaperone, sharing a similar substrate‐binding pocket. Using pulldowns and thermophoresis, we show that both HP1120 and a HP1120Δ126–144 deletion mutant bind to FlgK with nanomolar affinity, but not to the filament cap protein FliD, confirming that HP1120 is FlgN. Based on size‐exclusion chromatography and multi‐angle light scattering, H. pylori FlgN binds to FlgK with 1:1 stoichiometry. Overall structural similarities between FlgN and FliT suggest that substrate recognition on FlgN primarily involves an antiparallel coiled‐coil interface between the third helix of FlgN and the C‐terminal helix of the substrate. A FlgNΔ126–144 N100A, Y103A, S111I triple mutant targeting this interface significantly impairs the binding of FlgK. Finally, we demonstrate that FlgNΔ126–144, like FliT, binds with sub‐micromolar affinity to the flagellum ATPase FliI or its N‐terminal domain. Hence FlgN and FliT likely couple delivery of low‐abundance export substrates to the flagellum ATPase FliI.
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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) | 0.004 | 0.001 |
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".