Effect of an Orphan Response Regulator on <i>Streptococcus mutans</i> Sucrose-Dependent Adherence and Cariogenesis
Bibliographic record
Abstract
Streptococcus mutans is the principal acidogenic component of dental plaque that demineralizes tooth enamel, leading to dental decay. Cell-associated glucosyltransferases catalyze the sucrose-dependent synthesis of sticky glucan polymers that, together with glucan binding proteins, promote S. mutans adherence to teeth and cell aggregation. We generated an S. mutans Tn916 transposon mutant, GMS315, which is defective in sucrose-dependent adherence and significantly less cariogenic than the UA130 wild-type progenitor in germfree rats. The results of sodium dodecyl sulfate-polyacrylamide gel electrophoresis, Western blotting, and N-terminal sequence analysis confirmed the absence of a 155-kDa glucosyltransferase S (Gtf-S) from GMS315 protein profiles. Mapping of the unique transposon insertion in GMS315 revealed disruption of a putative regulatory region located upstream of gcrR, a gene previously described by Sato et al. that shares significant amino acid identity with other bacterial response regulators (Y. Sato, Y. Yamamoto, and H. Kizaki, FEMS Microbiol. Lett. 186: 187-191, 2000). The gcrR regulator, which we call "tarC," does not align with any of the 13 proposed two-component signal transduction systems derived from in silico analysis of the S. mutans genome, but rather represents one of several orphan response regulators in the genome. The results of Northern hybridization and/or real-time reverse transcription-PCR experiments reveal increased expression of both Gtf-S and glucan binding protein C (GbpC) in a tarC knockout mutant (GMS900), thereby supporting the notion that TarC acts as a negative transcriptional regulator. In addition, we noted that GMS900 has altered biofilm architecture relative to the wild type and is hypocariogenic in germfree rats. Taken collectively, these findings support a role for signal transduction in S. mutans sucrose-dependent adherence and aggregation and implicate TarC as a potential target for controlling S. mutans-induced cariogenesis.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.001 | 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) | 0.000 | 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".