Dual Conserved Periplasmic Loops Possess Essential Charge Characteristics That Support a Catch-and-Release Mechanism of O-antigen Polymerization by Wzy in Pseudomonas aeruginosa PAO1
Bibliographic record
Abstract
Heteropolymeric B-band lipopolysaccharide in Pseudomonas aeruginosa PAO1 is synthesized via the so-called Wzy-dependent pathway, requiring a functional Wzy for polymerization of O-antigen repeat units in the periplasm. Wzy is an integral inner membrane protein for which the detailed topology has been mapped in a recent investigation (Islam, S. T., Taylor, V. L., Qi, M., and Lam, J. S. (2010) mBio 1, e00189-10), revealing two principal periplasmic loops (PL), PL3 and PL5, each containing an RX10G motif. Despite considerable sequence conservation between the two loops, the isoelectric point for each peptide displayed marked differences, with PL3 exhibiting a net-positive charge and PL5 showing a net-negative charge. Data from site-directed mutagenesis of amino acids in each PL have led to the identification of several key Arg residues within the two RX10G motifs that are important for Wzy function, of which Arg176, Arg290, and Arg291 could not be functionally substituted with Lys. These observations support the proposed role of each PL in a catch-and-release mechanism for Wzy-mediated O-antigen polymerization. Heteropolymeric B-band lipopolysaccharide in Pseudomonas aeruginosa PAO1 is synthesized via the so-called Wzy-dependent pathway, requiring a functional Wzy for polymerization of O-antigen repeat units in the periplasm. Wzy is an integral inner membrane protein for which the detailed topology has been mapped in a recent investigation (Islam, S. T., Taylor, V. L., Qi, M., and Lam, J. S. (2010) mBio 1, e00189-10), revealing two principal periplasmic loops (PL), PL3 and PL5, each containing an RX10G motif. Despite considerable sequence conservation between the two loops, the isoelectric point for each peptide displayed marked differences, with PL3 exhibiting a net-positive charge and PL5 showing a net-negative charge. Data from site-directed mutagenesis of amino acids in each PL have led to the identification of several key Arg residues within the two RX10G motifs that are important for Wzy function, of which Arg176, Arg290, and Arg291 could not be functionally substituted with Lys. These observations support the proposed role of each PL in a catch-and-release mechanism for Wzy-mediated O-antigen polymerization.
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How this classification was reachedexpand
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 | 0.001 | 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 teacher head, 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".