The GtaR protein negatively regulates transcription of the <i>gtaRI</i> operon and modulates gene transfer agent (RcGTA) expression in <i>Rhodobacter capsulatus</i>
Bibliographic record
Abstract
The gtaI gene of Rhodobacter capsulatus encodes an N-acyl-homoserine lactone (acyl-HSL) synthase. Immediately 5' of the gtaI gene is ORF rcc00328 that encodes a potential acyl-HSL receptor protein. A combination of genetic and biochemical approaches showed that rcc00328 (renamed gtaR) modulates the production of a genetic exchange element called the gene transfer agent (RcGTA), and regulates the transcription of gtaI. Although gtaI mutants exhibited decreased levels of RcGTA production, mutagenesis of gtaR did not, whereas a gtaR/gtaI double mutant produced wild-type levels of RcGTA. Because mutagenesis of gtaR suppressed the effect of the gtaI mutation, we suggest that the GtaR protein is a negative transcriptional regulator of RcGTA gene expression. We discovered that the gtaR and gtaI genes are co-transcribed, and also negatively regulated by the GtaR protein in the absence of acyl-HSL. A His-tagged GtaR protein was purified, and DNA-binding experiments revealed a binding site in the promoter region of the gtaRI operon. This GtaR protein did not bind to the RcGTA promoter region, and therefore modulation of RcGTA production appears to require at least one additional factor. We found that RcGTA production was stimulated by spent media from other species, and identified exogenous acyl-HSLs that induce RcGTA.
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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) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| 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".