Spectroscopic Study of the CP43′ Complex and the PSI–CP43′ Supercomplex of the Cyanobacterium <i>Synechocystis</i> PCC 6803
Bibliographic record
Abstract
The PSI-CP43' supercomplex of the cyanobacterium Synechocystis PCC 6803, grown under iron-starvation conditions, consists of a trimeric core Photosystem I (PSI) complex and an outer ring of 18 CP43' light-harvesting complexes. We have investigated the electronic structure and excitation energy transfer (EET) pathways within the CP43' (also known as the isiA gene product) ring using low-temperature absorption, fluorescence, fluorescence excitation, and hole-burning (HB) spectroscopies. Analysis of the absorption spectra of PSI, CP43', and PSI-CP43' complexes suggests that there are 13 chlorophylls (Chls) per CP43' monomer, i.e., a number that was observed in the CP43 complex of Photosystem II (PSII) (Umena, Y. et al. Nature 2011, 473, 55-60). This is in contrast with the recent modeling studies of Zhang et al. (Biochim. Biophys. Acta 2010, 1797, 457-465), which suggested that IsiA likely contains 15 Chls. Modeling studies of various optical spectra of the CP43' ring using the uncorrelated EET model (Zazubovich, V.; Jankowiak, R. J. Lumin. 2007, 127, 245-250) suggest that CP43' monomers (in analogy to the CP43 complexes of the PSII core) also possess two quasi-degenerate low-energy states, A' and B'. The site distribution functions of states A' and B' maxima/full width at half-maximum (fwhm) are at 684 nm/180 cm(-1) and 683 nm/80 cm(-1), respectively. Our analysis shows that pigments mostly contributing to the lowest-energy A' and B' states must be located on the side of the CP43' complex facing the PSI core, a finding that contradicts the model of Zhang et al. but is in agreement with the model suggested by Nield et al. (Biochemistry2003, 42, 3180-3188). We demonstrate that the A'-A' and B'-B' EET between different monomers is possible, though with a slower rate than intramonomer A'-B' and/or B'-A' energy transfer.
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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 | 0.001 |
| 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".