<i>Actinobacillus</i> utilizes a binding-protein dependent ABC transporter to acquire Vitamin B <sub>6</sub>
Bibliographic record
Abstract
Abstract Bacteria require high efficiency uptake systems to survive and proliferate in nutrient limiting environments, such as those found in the host. The ABC transporters at the bacterial plasma membrane provide a mechanism for transport of many substrates. We recently demonstrated that an AfuABC operon, previously annotated as encoding a ferrous iron uptake system, is in fact a cyclic hexose/heptose-phosphate transporter with high selectivity and specificity for these metabolites. In this study, we examine a second operon containing a periplasmic binding protein discovered in Actinobacillus for its potential role in nutrient acquisition. Using electron density obtained from the crystal structure of the periplasmic binding protein we modeled a pyridoxal-5’-phosphate (P5P/PLP/Vitamin B 6 ) ligand into the atomic resolution electron density map. The identity of the Vitamin B 6 bound to this periplasmic binding protein was verified by isothermal titration calorimetry, microscale thermophoresis, and mass spectrometry, leading us to name the protein P5PA and the operon P5PAB. To illustrate the functional utility of this uptake system, we introduced the P5PAB operon from A. pleuropneumoniae into an E. coli K-12 strain that was devoid of a key enzyme required for Vitamin B 6 synthesis. The growth of this strain at low levels of Vitamin B 6 supports the role of this newly identify operon in Vitamin B 6 uptake.
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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".