A screen for novel targets casts polyphosphorylation of lysine as a common post‐translational modification
Bibliographic record
Abstract
Polyphosphates (polyP) are long chains of linked inorganic phosphates ranging from 3–1000s of residues in length. They are found in all organisms and play critical roles in a range of functions including blood clotting and bacterial virulence. Given its diverse roles, polyP is an attractive target for novel therapies. Recently, it was shown that polyP can be non‐enzymatically added to protein targets within poly‐acidic, serine, and lysine rich (PASK) motifs as a lysine post‐translational modification termed polyphosphorylation. This modification was described for two yeast proteins, Nsr1 and Top1. In yeast, polyP is initially synthesized by a polyP synthetase (VTC4) and subsequently added as a PTM non‐enzymatic. Our lab has developed a screen to assess polyphosphorylation of yeast substrates wherein we uncovered 25 novel substrates including a conserved network of proteins functioning in ribosome biogenesis. Disruption of this polyP synthesis through vtc4D deletion results in translation defects as measured by polysome profiling. Finally, we found that expression of E. coli polyP synthetase ( Ec PPK1) in vtc4D mutant yeast results in extreme sensitivity to rapamycin and cycloheximide, despite its ability to restore polyphosphorylation of multiple yeast targets. We propose a model wherein polyphosphorylation of unique targets regulates multiple aspects of cell growth. Moreover, regulation of polyphosphorylation in space and time is critical to preserve essential cell functions, such as ribosome function. Support or Funding Information The funding agencies that support this research are: University of Ottawa and CIHR This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .
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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) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| 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".