Site Directed Mutagenesis of Dextransucrase DsrM from <i>Weissella cibaria</i>: Transformation to a Reuteransucrase
Bibliographic record
Abstract
Glucansucrases produce α-glucans and gluco-oligosaccharides; the linkage type and molecular weight of glucans impacts their functionality. This study compared the catalytic specificities of dextransucrase DsrM from Weissella cibaria 10M and derivatives of this enzymes with GtfA from Lactobacillus reuteri TMW1.656. The N-variable region, which is dispensable for GtfA activity, was essential for DsrM activity. Parallel amino acid substitutions in DsrM-ΔS and GtfA-ΔN indicated that the acceptor binding site residues determining the linkage type differ in these enzymes. DsrM-V583P:V586I had comparable enzyme activity as the respective GtfA derivative but did not increase the proportion of α-(1→4) linkages. DsrM-S622N had low enzyme activity and an unaltered proportion of α-(1→4) linkages while the analogous GtfA-S1062N maintained enzyme activity but increased the proportion of α-(1→4) linkages. This study of dextransucrase from Weissella spp. thus elucidated differences between glucansucrases and will facilitate study of the structure-function relationships of dextran and isomalto-oligosaccharides.
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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 | 0.000 |
| 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".