<i>Pseudomonas aeruginosa</i> TfpW is a multifunctional D-Ara <i>f</i> glycosyltransferase and oligosaccharyltransferase
Bibliographic record
Abstract
ABSTRACT TfpW is an oligosaccharyltransferase that modifies the subunits of type IV pili from group IV strains of Pseudomonas aeruginosa with oligomers of α-1,5-linked-D-arabinofuranose (D-Ara f ). Besides its oligosaccharyltransferase activity, TfpW may be responsible for periplasmic translocation and polymerization of D-Ara f . Here we investigated these potential roles of TfpW in Pa5196 pilin glycosylation. Topology studies confirmed the periplasmic location of loop 1 and the large C-terminus domain, however the central portion of TfpW had an indeterminate configuration. Reconstitution of the Pa5196 pilin glycosylation system by providing pilA , tfpW +/- tfpX and the D-Ara f biosynthesis genes PsPA7_6246-6249 showed that TfpW is sufficient for glycan polymerization and transfer to pilins in P. aeruginosa PAO1, while TfpX is also necessary in Escherichia coli . In addition to PsPA7 _ 6246, DprE1 (PsPA7 _ 6248) and DprE2 (PsPA7 _ 6249), the GtrA-like component PsPA7 _ 6247 was required for pilin glycosylation in E. coli versus PAO1. In a PAO1 Δ arnE/F mutant, loss of PsPA7_6247 expression decreased the level of pilin glycosylation, suggesting that arnE/F may play a role in pilin glycosylation when PsPA7_6247 is absent. Bacterial two-hybrid studies showed interactions of TfpW with itself, TfpX, PsPA7 _ 6247 and DprE2, suggesting the formation of a complex that enables efficient pilin glycosylation. Fluorescence microscopy of E. coli and Pa5196 ΔdprE1 expressing a DprE1-sGFP fusion showed that the protein is expressed in the cytoplasm, supporting our model that includes cytoplasmic biosynthesis of the lipid carrier-linked D-Ara f precursor prior to its periplasmic translocation. Together these data suggest that TfpW may be the first example of a trifunctional flippase, glycosyltransferase, and oligosaccharyltransferase.
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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 | 0.001 |
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".