Shikimate Kinase-Like 1 Participates in an Ancient and Conserved Role Contributing to Chloroplast Biogenesis in Land Plants
Bibliographic record
Abstract
Shikimate kinase-like 1 (SKL1) plays an essential role in chloroplast biogenesis in Arabidopsis thaliana whereby mutants present a pigment-defective phenotype. The inability to identify SKL1 in organisms predating land plants suggests an important role for this gene coinciding with the emergence of terrestrial plants. A role for SKL1 in chloroplast biogenesis has previously been determined in Arabidopsis; however, the biological function for SKL1 has not been established in early land plants. In the present study, we provided functional and evolutionary insights into the diversification of SKL1 in the early land plant Marchantia polymorpha. We identified the SK gene homologs common to all land plants, two of which were shown to have high sequence similarity to SK. We confirmed that one member possessed shikimate kinase activity, whereas the second member is inactive. These findings led us to identify MpSK (Mp3g21830) and infer the identity of MpSKL1 (Mp6g03600). Consistent with previous studies in Arabidopsis, disruption of MpSKL1 in Marchantia resulted in a pigment-defective phenotype with abnormal chloroplast morphology and thylakoid network organization. Given an early origin of SKL1 in land plant evolution, we investigated requisite structural modifications to an ancestral SK that led to the functional diversification of SKL1. We provided evidence that SKL1 displays an open and accessible substrate binding pocket, conferring its biological function for chloroplast biogenesis. Together, our results demonstrate that the acquisition of SKL1 corresponds with the emergence of terrestrial land plants and that this biological function is conserved across distant plant lineages.
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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) | 0.000 | 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) | 0.001 | 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".