Identification of a novel adhesin involved in acid-induced adhesion of enterohaemorrhagic Escherichia coli O157 : H7
Bibliographic record
Abstract
Enterohaemorrhagic Escherichia coli (EHEC) survives exposure to acute acid stress during gastric passage and progresses to colonize the large intestine. We previously reported that acid stress significantly increases host adhesion of EHEC O157 : H7 and is associated with a coincident upregulation of the expression of a putative adhesin gene, yadK. Further gene expression analysis now confirms that yadK is minimally transcribed under unstressed conditions and is significantly upregulated under acid stress. Immunoblotting with an anti-YadK polyclonal antiserum demonstrates that YadK protein is also upregulated after acid stress. Disruption of yadK results in loss of the acid-induced adhesion increase seen for wild-type EHEC to human epithelial cells in vitro and complementation in trans fully restores the acid-induced adhesion phenotype to the wild-type level. Significantly, no difference is observed in adhesion of the unstressed yadK mutant relative to wild-type, indicating that YadK does not play a role in adhesion of unstressed EHEC. Anti-YadK antiserum inhibits the acid-induced adhesion enhancement of EHEC but has no effect on adhesion of unstressed EHEC. There is no significant difference in the viability of either the unstressed or the acid-stressed yadK mutant relative to the similarly treated wild-type, suggesting that yadK is not involved in acid tolerance. These results provide persuasive evidence that YadK plays a significant role in the adhesion of acid-stressed EHEC to epithelial cells, and support a role for acid stress as a factor which may regulate bacteria-host attachment and lead to increased EHEC colonization and virulence.
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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) | 0.000 | 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".