Characterization of the Induction and Cellular Role of the BaeSR Two-Component Envelope Stress Response of Escherichia coli
Bibliographic record
Abstract
The bacterial cell envelope is the interface between a bacterium and its environment and is constantly exposed to environmental changes. The BaeSR two-component system regulates one of six envelope stress responses in Escherichia coli and is induced by spheroplasting, overexpression of the pilin subunit PapG, and exposure to indole. The known BaeR regulon is small, consisting of eight genes, mdtABCD-baeSR, acrD, and spy, two of which encode the BaeSR two-component system itself. In this study, we investigated the molecular nature of the BaeS-inducing cue and the cellular role of the BaeSR envelope stress response. We demonstrated that at least two flavonoids and sodium tungstate are novel inducers of the BaeSR response. Interestingly, flavonoids and sodium tungstate led to much stronger induction of the BaeSR response in an mdtA efflux pump mutant, while indole did not. These findings are consistent with the hypothesis that flavonoids and sodium tungstate are natural substrates of the MdtABC efflux pump. Indole has recently been implicated in cell-cell signaling and biofilm repression through a putative interaction with the LuxR homologue SdiA. Using genetic analyses, we found that induction of the BaeSR response by indole occurs via a pathway separate from the SdiA biofilm pathway. Further, we demonstrated that the BaeSR response does not influence biofilm formation, nor is it involved in indole-mediated inhibition of biofilm formation. We hypothesize that the main function of the Bae response is to upregulate efflux pump expression in response to specific envelope-damaging agents.
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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 | 0.000 |
| 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 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".