Members of the Sinorhizobium meliloti ChvI regulon identified by a DNA binding screen
Bibliographic record
Abstract
BACKGROUND: The Sinorhizobium meliloti ExoS/ChvI two component regulatory system is required for N2-fixing symbiosis and exopolysaccharide synthesis. Orthologous systems are present in other Alphaproteobacteria, and in many instances have been shown to be necessary for normal interactions with corresponding eukaryotic hosts. Only a few transcriptional regulation targets have been determined, and as a result there is limited understanding of the mechanisms that are controlled by the system. RESULTS: In an attempt to better define the members of the regulon, we have applied a simple in vitro electrophoretic screen for DNA fragments that are bound by the ChvI response regulator protein. Several putative transcriptional targets were identified and three were further examined by reporter gene fusion experiments for transcriptional regulation. Two were confirmed to be repressed by ChvI, while one was activated by ChvI. CONCLUSIONS: Our results suggest a role for ChvI as both a direct activator and repressor of transcription. The identities and functions of many of these genes suggest explanations for some aspects of the pleiotropic phenotype of exoS and chvI mutants. This work paves the way for in depth characterization of the ExoS/ChvI regulon and its potential role in directing bacteria-host relationships.
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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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| 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) | 0.002 | 0.001 |
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".