A thylakoid‐located carbonic anhydrase regulates <scp>CO</scp><sub>2</sub> uptake in the cyanobacterium <i>Synechocystis</i> sp. PCC 6803
Bibliographic record
Abstract
Summary Carbonic anhydrases ( CA s) are involved in CO 2 uptake and conversion, a fundamental process in photosynthetic organisms. Nevertheless, the mechanism underlying the regulation of CO 2 uptake and intracellular conversion in cyanobacteria is largely unknown. We report the characterization of a previously unrecognized thylakoid‐located CA Slr0051 (EcaB) from the cyanobacterium Synechocystis sp. PCC 6803, which possesses CA activity to regulate CO 2 uptake. Inactivation of ecaB stimulated CO 2 hydration in the thylakoids, suppressed by the classical CA inhibitor acetazolamide. Absence of ecaB increased the reduced state of the photosynthetic electron transport system, lowered the rate of photosynthetic O 2 evolution at high light ( HL ) and pH , and decreased the cellular affinity for extracellular inorganic carbon. Furthermore, EcaB was upregulated in cells grown at limiting CO 2 concentration or HL in tandem with CupA. EcaB is mainly located in the thylakoid membranes where it interacts with CupA and CupB involved in CO 2 uptake by converting it to bicarbonate. We propose that modulation of the EcaB level and activity in response to CO 2 changes, illumination or pH reversibly regulates its conversion to HCO 3 by the two CO 2 ‐uptake systems (CupA, CupB), dissipating the excess HCO 3 − and alleviating photoinhibition, and thereby optimizes photosynthesis, especially under HL and alkaline conditions.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
How this classification was reachedexpand
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 | 0.001 | 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 teacher head, 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".