AmtB Is Necessary for NH <sub>4</sub> <sup>+</sup> -Induced Nitrogenase Switch-Off and ADP-Ribosylation in <i>Rhodobacter capsulatus</i>
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Bibliographic record
Abstract
Rhodobacter capsulatus possesses two genes potentially coding for ammonia transporters, amtB and amtY. In order to better understand their role in the physiology of this bacterium and their possible significance in nitrogen fixation, we created single-knockout mutants. Strains mutated in either amtB or amtY did not show a growth defect under any condition tested and were still capable of taking up ammonia at nearly wild-type rates, but an amtB mutant was no longer capable of transporting methylamine. The amtB strain but not the amtY strain was also totally defective in carrying out ADP-ribosylation of Fe-protein or the switch-off of in vivo nitrogenase activity in response to NH(4)(+) addition. ADP-ribosylation in response to darkness was unaffected in amtB and amtBY strains, and glutamine synthetase activity was normally regulated in these strains in response to ammonium addition, suggesting that one role of AmtB is to function as an ammonia sensor for the processes that regulate nitrogenase activity.
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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 | 0.000 |
| 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 it