NTE1-encoded Phosphatidylcholine Phospholipase B Regulates Transcription of Phospholipid Biosynthetic Genes
Bibliographic record
Abstract
The Saccharomyces cerevisiae NTE1 gene encodes an evolutionarily conserved phospholipase B localized to the endoplasmic reticulum (ER) that degrades phosphatidylcholine (PC) generating glycerophosphocholine and free fatty acids. We show here that the activity of NTE1-encoded phospholipase B (Nte1p) prevents the attenuation of transcription of genes encoding enzymes involved in phospholipid synthesis in response to increased rates of PC synthesis by affecting the nuclear localization of the transcriptional repressor Opi1p. Nte1p activity becomes necessary for cells growing in inositol-free media under conditions of high rates of PC synthesis elicited by the presence of choline at 37 degrees C. The specific choline transporter encoded by the HNM1 gene is necessary for the burst of PC synthesis observed at 37 degrees C as follows: (i) Nte1p is dispensable in an hnm1Delta strain under these conditions, and (ii) there is a 3-fold increase in the rate of choline transport via the Hnm1p choline transporter upon a shift to 37 degrees C. Overexpression of NTE1 alleviated the inositol auxotrophy of a plethora of mutants, including scs2Delta, scs3Delta, ire1Delta, and hac1Delta among others. Overexpression of NTE1 sustained phospholipid synthesis gene transcription under conditions that normally repress transcription. This effect was also observed in a strain defective in the activation of free fatty acids for phosphatidic acid synthesis. No changes in the levels of phosphatidic acid were detected under conditions of altered expression of NTE1. Consistent with a synthetic impairment between challenged ER function and inositol deprivation, increased expression of NTE1 improved the growth of cells exposed to tunicamycin in the absence of inositol. We describe a new role for Nte1p toward membrane homeostasis regulating phospholipid synthesis gene transcription. We propose that Nte1p activity, by controlling PC abundance at the ER, affects lateral membrane packing and that this parameter, in turn, impacts the repressing transcriptional activity of Opi1p, the main regulator of phospholipid synthesis gene transcription.
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 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) | 0.000 | 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".