Duplication of Teichoic Acid Biosynthetic Genes in <i>Staphylococcus aureus</i> Leads to Functionally Redundant Poly(Ribitol Phosphate) Polymerases
Bibliographic record
Abstract
Wall teichoic acids are anionic phosphate-rich polymers that are part of the complex meshwork of carbohydrates that make up the gram-positive cell wall. These polymers are essential to the proper rod-shaped morphology of Bacillus subtilis and have been shown to be an important virulence determinant in the nosocomial opportunistic pathogen Staphylococcus aureus. Together, sequence-based studies, in vitro experiments with biosynthetic proteins, and analyses of the chemical structure of wall teichoic acid have begun to shed considerable light on our understanding of the biogenesis of this polymer. Nevertheless, some paradoxes remain unresolved. One of these involves a putative duplication of genes linked to CDP-ribitol synthesis (tarI'J' and tarIJ) as well as poly(ribitol phosphate) polymerization (tarK and tarL) in S. aureus. In the work reported here, we performed careful studies of the dispensability of each gene and discovered a functional redundancy in the duplicated gene clusters. We were able to create mutants in either of the putative ribitol phosphate polymerases (encoded by tarK and tarL) without affecting teichoic acid levels in the S. aureus cell wall. Although genes linked to CDP-ribitol synthesis are also duplicated, a null mutant in only one of these (tarI'J') could be obtained, while tarIJ remained essential. Suppression analysis of the tarIJ null mutant indicated that the mechanism of dysfunction in tarI'J' is due to poor translation of the TarJ' enzyme, which catalyzes the rate-limiting step in CDP-ribitol formation. This work provides new insights into understanding the complex synthetic steps of the ribitol phosphate polymer in S. aureus and has implications on specifically targeting enzymes involved in polymer biosynthesis for antimicrobial design.
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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 | 0.000 | 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 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".