Expression, Purification, and Biochemical Characterization of WbpP, a New UDP-GlcNAc C4 Epimerase from Pseudomonas aeruginosa Serotype O6
Why this work is in the frame
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Bibliographic record
Abstract
B-band lipopolysaccharide is an important virulence factor of the opportunistic pathogen Pseudomonas aeruginosa. WbpP is an enzyme essential for B-band lipopolysaccharide production in serotype O6. Sequence analysis suggests that it is involved in the formation of N-acetylgalacturonic acid. To test this hypothesis, overexpression and biochemical characterization of WbpP were performed. By using spectrophotometric assays and capillary electrophoresis, we show that WbpP is a UDP-GlcNAc C4 epimerase. The K(m) for UDP-GlcNAc and UDP-GalNAc are 197 and 224 micrometer, respectively. At equilibrium, 70% of UDP-GalNAc is converted to UDP-GlcNAc, whereas the yield of the reverse reaction is only 30%. The enzyme can also catalyze the inter-conversion of non-acetylated substrates, although the efficiency of catalysis is significantly lower. Only 15 and 40% of UDP-Glc and UDP-Gal, respectively, are converted at equilibrium. WbpP contains tightly bound NAD(H) and does not require additional cofactors for activity. It exists as a dimer in its native state. This paper is the first report of expression and characterization of a C4 UDP-GlcNAc epimerase at the biochemical level. Moreover, the characterization of the enzymatic function of WbpP will help clarify ambiguous surface carbohydrate biosynthetic pathways in P. aeruginosa and other organisms where homologues of WbpP exist.
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Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| 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) | 0.004 | 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 it