The Mechanism of Quorum Sensing Inhibition in <i>Streptococcus pyogenes</i> by the Phage Protein Paratox
Bibliographic record
Abstract
Streptococcus pyogenes is a causative agent of pharyngitis and necrotizing fasciitis. Key to its pathogenicity are numerous prophages spread throughout its genome that encode deadly toxins. These prophages also encode several proteins whose biological function is unknown. Of particular interest is the conserved phage protein paratox (Prx), which is genetically linked to phage toxin genes. Our past results have shown that Prx expression is regulated by the natural competence ComRS quorum sensing pathway, and that Prx itself is a negative regulator of ComRS. Prx directly binds the transcription factor and quorum sensing receptor ComR and inhibits its ability to bind DNA by an unknown mechanism. As ComR undergoes a significant conformational change upon binding the peptide pheromone XIP, we hypothesize that Prx employs a novel mechanism of protein‐protein binding and inhibition. Using a combination of structural biology and biochemistry, including X‐ray crystallography, small‐angle X‐ray scattering (SAXS), and various fluorescence assays, we have been able to elucidate the molecular details of how Prx manipulates the conformation of ComR to prevent activation by the XIP pheromone. Our results not only reveal a dynamic protein‐protein binding mechanism, but further demonstrate the myriad roles that phage proteins have evolved to regulate the pathways of their hosts for self‐preservation.
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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 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 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".