Isolation of y-Aminobutyrate (GABA) Utilizing Mutant Strains and Characterization of Factors Sufficient for GABA Utilization as a Carbon and Nitrogen Source
Bibliographic record
Abstract
We have previously found that the 𝘨𝘢𝘣 operon of 𝘌𝘴𝘤𝘩𝘦𝘳𝘪𝘤𝘩𝘪𝘢 𝘤𝘰𝘭𝘪 is RpoS regulated suggesting that it plays an important role during stationary phase growth. The specific role of the 𝘨𝘢𝘣 operon is metabolism of γ-aminobutyrate (GABA). GABA, a four carbon amino acid, is the product of the glutamate decarboxylase reaction in 𝘌. 𝘤𝘰𝘭𝘪 and can serve as a source of carbon and nitrogen for members of the 𝘌𝘯𝘵𝘦𝘳𝘰𝘣𝘢𝘤𝘵𝘦𝘳𝘪𝘢𝘤𝘦𝘢𝘦. Interestingly, we found that we could isolate GABA utilizing mutants even when they carried mutations that were predicted to abolish gab function. However, we were only able to isolate GABA utilizing mutants in the 𝘳𝘱𝘰𝘚⁺ background. This suggests two additional features of GABA metabolism in 𝘌. 𝘤𝘰𝘭𝘪. One, that the 𝘨𝘢𝘣 operon in 𝘌𝘴𝘤𝘩𝘦𝘳𝘪𝘤𝘩𝘪𝘢 𝘤𝘰𝘭𝘪 is indeed dispensable for GABA utilization. Secondly, other RpoS regulated functions, independent of 𝘨𝘢𝘣-encoded functions, may allow the cell to metabolize GABA Finally, we have also investigated the inducing effects of GABA on 𝘨𝘢𝘣 expression in minimal and rich media and the role of glutamate in osmo-tolerance and acid adaptation.
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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 | 0.001 |
| 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 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 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".