Novel gene products associated with NdhD3/D4‐containing NDH‐1 complexes are involved in photosynthetic CO<sub>2</sub> hydration in the cyanobacterium, <i>Synechococcus</i> sp. PCC7942
Bibliographic record
Abstract
Cyanobacteria possess light-dependent CO2 uptake activity that results in the net hydration of CO2 to HCO3- and may involve a protein-mediated carbonic anhydrase (CA)-like activity. This process is vital for the survival of cyanobacteria and may be a contributing factor in the ecological success of this group of organisms. Here, via isolation of mutants of Synechococcus sp. PCC7942 that cannot grow under low-CO2 conditions, we have identified two novel genes, chpX and chpY, that are involved in light-dependent CO2 hydration and CO2 uptake reactions; co-inactivation of both these genes abolished both activities. The function and mechanism of the CO2 uptake systems supported by each chp gene product differs, with each associated with functionally distinct NAD(P)H dehydrogenase (NDH-1) complexes. The ChpX system has a low affinity for CO2 and is dependent on photosystem I cyclic electron transport, whereas the inducible ChpY system has a high affinity for CO2 and is dependent on linear electron transport. We believe that ChpX and ChpY are involved in a unique, net hydration of CO2 to HCO3-, that is coupled electron flow within the NDH-1 complex on the thylakoid membrane.
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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 | 0.000 | 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) | 0.001 | 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".