Structure‐based mutagenesis of SigE verifies the importance of hydrophobic and electrostatic residues in type III chaperone function
Bibliographic record
Abstract
Despite sharing little sequence identity, most type III chaperones display a similar homodimeric structure characterized by negative charges distributed broadly over their entire surface, interspersed with hydrophobic patches. Here we have used SigE from Salmonella as a model for class IA type III chaperones to investigate the role of these surface-exposed residues in chaperone function. SigE is essential for the stability, secretion and translocation of its cognate effector, SopB (SigD). We analysed the effect of mutating nine conserved hydrophobic and electronegative surface-exposed amino acids of SigE on SopB binding, stability, secretion and translocation. Six of these mutations affected some aspect of SigE function (Leu14, Asp20, Leu22, Leu23, Ile25 and Asp51) and three were without effect (Leu54, Glu92 and Glu99). Our results highlight that both hydrophobic and electronegative surfaces are required for the function of SigE and provide an important basis for the prediction of side-chain requirements for other chaperone-effector pairs.
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) | 0.000 | 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".