Phosphoglycerate dehydrogenase is required for kernel development and defines a predominant serine synthesis pathway in maize
Bibliographic record
Abstract
Serine functions as both a substrate for protein biosynthesis and a signaling molecule for growth and development. However, the mechanism remains poorly understood. Here, we cloned and functionally characterized the maize (Zea mays) gene Dek20, which encodes phosphoglycerate dehydrogenase1 (PGDH1), the rate-limiting enzyme in the phosphorylated pathway of serine biosynthesis (PPSB). The dek20(Ser282Leu) mutation disrupts the interaction between residues Ser282 and His284, leading to the release of His284, which subsequently binds NAD+/NADH to inhibit serine biosynthesis. Consequently, serine content decreases dramatically, and the cellular response to nutrient starvation is enriched in transcriptome analysis. Serine deficiency triggers tRNASer degradation and reduced translation elongation at serine codons. The stalled ribosomes activate General Control Nonderepressible 2 (GCN2) kinase, which affects the phosphorylation of eukaryotic initiation factor 2α (eIF2α) and ribosomal protein S6 kinase (S6 K), furtherly inhibiting translation initiation. Consistent with these findings, polysome profiling and Ribo-seq analysis revealed a marked decrease in translation efficiency in dek20. Notably, proteins essential for storage compound biosynthesis and cell cycle progression exhibit reduced translation in dek20. Collectively, our findings reveal the primary serine biosynthesis pathway and a mechanism for monitoring amino acid levels in maize, the model plant with C4 photosynthesis.
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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 | 0.001 |
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".