The Minor Pilin Subunit Sgp2 Is Necessary for Assembly of the Pilus Encoded by the<i>srtG</i>Cluster of<i>Streptococcus suis</i>
Bibliographic record
Abstract
Gram-positive pili are composed of covalently bound pilin subunits whose assembly is mediated via a pilus-specific sortase(s). Major subunits constitute the pilus backbone and are therefore essential for pilus formation. Minor subunits are also incorporated into the pilus, but they are considered to be dispensable for backbone formation. The srtG cluster is one of the putative pilus gene clusters identified in the major swine pathogen Streptococcus suis. It consists of one sortase gene (srtG) and two putative pilin subunit genes (sgp1 and sgp2). In this study, by constructing mutants for each of the genes in the cluster and by both immunoblotting and immunogold electron microscopic analysis with antibodies against Sgp1 and Sgp2, we found that the srtG cluster mediates the expression of pilus-like structures in S. suis strain 89/1591. In this pilus, Sgp1 forms the backbone, whereas Sgp2 is incorporated as the minor subunit. In accordance with the current model of pilus assembly by Gram-positive organisms, the major subunit Sgp1 was indispensable for backbone formation and the cognate sortase SrtG mediated the polymerization of both subunits. However, unlike other well-characterized Gram-positive bacterial pili, the minor subunit Sgp2 was required for polymerization of the major subunit Sgp1. Because Sgp2 homologues are encoded in several other Gram-positive bacterial pilus gene clusters, in some types of pili, minor pilin subunits may contribute to backbone formation by a novel mechanism.
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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) | 0.001 | 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".