Expression of the Streptococcus mutans essential two-component regulatory system VicRK is pH and growth-phase dependent and controlled by the LiaFSR three-component regulatory system
Bibliographic record
Abstract
As an inhabitant of the human oral cavity, Streptococcus mutans faces frequent environmental changes. Two-component regulatory systems (TCSs) play a critical role in responding to these changes. Recently, an essential TCS, VicRKX, has been identified. The objective of this study was to identify the environmental signal and bacterial factors regulating the expression of the vicRKX operon. The promoter of the vicRKX operon was fused to a promoterless lacZ reporter gene and introduced into S. mutans UA159. LacZ plate assay identified pH, vancomycin, ampicillin, penicillin G and polymyxin B, but not carbohydrates, as factors affecting expression. Using RNA dot-blotting, high levels of vicR transcript were observed in cells at the mid- and late-exponential phase of growth and in cells grown in media buffered at pH 7.8. Given that vicR expression was pH-dependent, the genes encoding a putative pH-sensing three-component regulatory system (LiaFSR) were deleted. The liaS mutant exhibited upregulation of vicR regardless of the growth condition. The role of VicK, VicX, and the competence-signal peptide (CSP) was also investigated; the results showed that vicR expression was not autoregulated and was downregulated by the CSP in a ComX-independent manner. In conclusion, the expression of vicRKX is influenced by culture pH, growth phase and antibiotic stress, and is regulated by LiaFRS.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 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) | 0.000 | 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 teacher head, 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".