The <i>Vibrio cholerae</i> Mrp System: Cation/Proton Antiport Properties and Enhancement of Bile Salt Resistance in a Heterologous Host
Why this work is in the frame
A frame that forgets how it found something cannot be audited. These are the routes that admitted this work.
Bibliographic record
Abstract
The <i>mrp</i> operon from <i>Vibrio cholerae </i>encoding a putative multisubunit Na<sup>+</sup>/H<sup>+</sup> antiporter was cloned and functionally expressed in the antiporter-deficient strain of <i>Escherichia coli</i> EP432. Cells of EP432 expressing Vc-Mrp exhibited resistance to Na<sup>+</sup> and Li<sup>+</sup> as well as to natural bile salts such as sodium cholate and taurocholate. When assayed in everted membrane vesicles of the <i>E. coli </i>EP432 host, Vc-Mrp had sufficiently high antiport activity to facilitate the first extensive analysis of Mrp system from a Gram-negative bacterium encoded by a group 2 <i>mrp</i> operon. Vc-Mrp was found to exchange protons for Li<sup>+</sup>, Na<sup>+</sup>, and K<sup>+</sup> ions in pH-dependent manner with maximal activity at pH 9.0–9.5. Exchange was electrogenic (more than one H<sup>+</sup> translocated per cation moved in opposite direction). The apparent K<sub>m</sub> at pH 9.0 was 1.08, 1.30, and 68.5 m<i>M</i> for Li<sup>+</sup>, Na<sup>+</sup>, and K<sup>+</sup>, respectively. Kinetic analyses suggested that Vc-Mrp operates in a binding exchange mode with all cations and protons competing for binding to the antiporter. The robust ion antiport activity of Vc-Mrp in sub-bacterial vesicles and its effect on bile resistance of the heterologous host make Vc-Mrp an attractive experimental model for the further studies of biochemistry and physiology of Mrp systems.
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.
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 | 0.001 |
| 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 it