A β-(1,2)-Glycosynthase and an Attempted Selection Method for the Directed Evolution of Glycosynthases
Bibliographic record
Abstract
Understanding how enzymes mediate catalysis is a key to their reprogramming for biotechnological applications. The family 3 retaining glycosidase postulated to be involved in erythromycin self-resistance was cloned, recombinantly expressed in Escherichia coli, purified, and characterized. Bioinformatics analysis allowed the identification of the acid/base and nucleophile residues, and mutation of these residues resulted in hydrolytically inactive proteins. One mutant was able to synthesize a glycosidic linkage using α-glucosyl fluoride as a donor and macrolide antibiotics as acceptors. This shows an unprecedented application of glycosynthase technology in accomplishing a challenging β-(1,2)-glycosylation of an amino sugar. This work also provides the first biochemical characterization of the EryBI protein and supports its role in the self-resistance mechanism involved in erythromycin biosynthesis. An in vivo selection approach was used in an attempt to spur evolution of the glycosynthase, and the results from the attempted selection method provide insight into the requirements for in vivo directed evolution of glycosynthases.
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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) | 0.000 | 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 | 0.001 |
| Insufficient payload (model declined to judge) | 0.000 | 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".