A Highly Charged Region in the Middle Domain of Plant ER‐Localized HSP90 is Required for ER Stress Resistance
Bibliographic record
Abstract
Heat shock protein HSP90 is a highly conserved molecular chaperone that is involved in modulating a multitude of cellular processes under both physiological and stress conditions. In Arabidopsis, there are seven HSP90 isoforms (HSP90.1 to HSP90.7) that are localized in the cytoplasm/nucleus, mitochondrion, chloroplast and endoplasmic reticulum (ER) where protein folding actively takes place. In this study, we analyzed the sequence of ER‐localized Arabidopsis HSP90.7 and the other ER GRP94 proteins from plants and animals, and identified a short, charged region that is specifically present in the middle domain of plant‐derived GRP94 proteins. To understand the role of this charged region, we analyzed transgenic plants that express a mutant protein HSP90.7 Δ22 , which has this charged region deleted. We showed that seedlings expressing HSP90.7 Δ22 have significantly enhanced sensitivity to ER stress induced by tunicamycin or high concentration of calcium, although its general chaperone activity in preventing model protein from heat‐induced aggregation was not significantly affected. We also analyzed the ATP‐binding and hydrolysis activity of both wild type and mutant HSP90.7 proteins, and found that they have slightly different ATP‐binding affinities. Finally, using yeast two‐hybrid screen, we identified a small set of HSP90.7 interactors and showed that the charged region is not required for the candidate client interaction, although it may affect their binding affinity, thus providing potential targets for further investigation of HSP90.7 functions. This work was supported by an NSERC Discovery Grant (371789‐2009) awarded to RZ.
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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".