Role of helix II residues in the conformation and substrate properties of acyl carrier protein
Bibliographic record
Abstract
Acyl carrier protein (ACP) and its fatty acylated derivatives are substrates for a variety of enzymes involved in the synthesis of bacterial lipids, endotoxins, and other products. ACP is believed to interact with most of these enzymes through a central acidic α‐helix (helix II) containing weak divalent cation binding sites at its N‐ and C‐termini. Site‐directed mutagenesis was used to examine the roles of specific helix II residues on the conformation of Vibrio harveyi ACP and its ability to support holo‐ACP synthase (ACPS), acyl‐ACP synthetase (AAS), fatty acid synthase (FAS) and UDP‐GlcNAc acyltransferase (LpxA) activities. Neutralization of acidic residues at either end of helix II stabilized the helical conformation of ACP but had distinct effects on ACP‐dependent enzymes: N‐terminal mutations (eg. D35N) affected ACPS activity, while C‐terminal mutations had more impact on AAS and LpxA activities. FAS was sensitive to neutralizing mutations at both ends of helix II. In contrast, replacement of selected residues along helix II with tryptophan (eg. A45W, L46W, and F50W) had no major effect either on the conformation of ACP or on its substrate properties with AAS or FAS, although LpxA activity was affected. Our results support helix II as the major recognition domain for ACP‐dependent enzymes, but suggest that different enzymes might have distinct binding determinants in this region ( supported by CIHR and NSERC ).
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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 | 0.000 |
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".