<i>lfnA</i> from <i>Pseudomonas aeruginosa</i> O12 and <i>wbuX</i> from <i>Escherichia coli</i> O145 Encode Membrane-Associated Proteins and Are Required for Expression of 2,6-Dideoxy-2-Acetamidino- <scp>l</scp> -Galactose in Lipopolysaccharide O Antigen
Bibliographic record
Abstract
The rare sugar 2,6-dideoxy-2-acetamidino-L-galactose (L-FucNAm) is found only in bacteria and is a component of cell surface glycans in a number of pathogenic species, including the O antigens of Pseudomonas aeruginosa serotype O12 and Escherichia coli O145. P. aeruginosa is an important opportunistic pathogen, and the O12 serotype is associated with multidrug-resistant epidemic outbreaks. O145 is one of the classic non-O157 serotypes associated with Shiga toxin-producing, enterohemorrhagic E. coli. The acetamidino (NAm) moiety of L-FucNAm is of interest, because at neutral pH it contributes a positive charge to the cell surface, and we aimed to characterize the biosynthesis of this functional group. The pathway is not known, but expression of NAm-modified sugars coincides with the presence of a pseA homologue in the relevant biosynthetic locus. PseA is a putative amidotransferase required for synthesis of a NAm-modified sugar in Campylobacter jejuni. In P. aeruginosa O12 and E. coli O145, the pseA homologues are lfnA and wbuX, respectively, and we hypothesized that these genes function in L-FucNAm biosynthesis. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis, Western blotting, and nuclear magnetic resonance analysis of the lfnA mutant O-antigen structure indicated that the mutant expresses 2,6-dideoxy-2-acetamido-L-galactose (L-FucNAc) in place of L-FucNAm. The mutation could be complemented by expression of either His(6)-tagged lfnA or wbuX in trans, confirming that these genes are functional homologues and that they are required for NAm moiety synthesis. Both proteins retained their activity when fused to a His(6) tag and localized to the membrane fraction. These data will assist future biochemical investigation of this pathway.
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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.004 | 0.003 |
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".