The <i>Staphylococcus aureus</i> esterase FmtA is essential for wall teichoic acid D-alanylation
Bibliographic record
Abstract
ABSTRACT Staphylococcus aureus teichoic acids are anionic glycopolymers covalently attached to peptidoglycan (wall teichoic acids, WTAs) or anchored to the phospholipid membrane (lipoteichoic acids, LTAs). The post-synthetic addition of D-alanine (D-Ala) residues to these polymers modulates surface charge and contributes to pathogen survival in the host environment. Despite this importance, the underlying mechanisms controlling WTA D-alanylation remain a significant area for further investigation. Here, we demonstrate that the teichoic acid D-Ala esterase, FmtA, is essential for WTA D-alanylation. The inactivation of fmtA results in a more negative net surface charge, impacting host adhesion, biofilm formation, and cell aggregation. We found that LTA from fmtA -deficient strains retains normal D-alanylation levels, while WTA is almost devoid of D-Ala. These data support the notion that LTA provides the D-Ala for WTA modification, a process dependent on FmtA. IMPORTANCE The D-alanine (D-Ala) modification of Staphylococcus aureus teichoic acids influences bacterial interactions and survival under stress. While this modification is important for host survival, the mechanisms underlying wall teichoic acid (WTA) D-alanylation remain unclear. A deeper understanding of this process could lead to the development of targeted therapies to combat S. aureus infections. We have identified FmtA as essential for this process, supporting the idea that lipoteichoic acid (LTA) provides the D-Ala used to modify WTAs. Our findings highlight a critical gap in understanding this mechanism: an acyltransferase must incorporate the D-Ala released from LTAs by FmtA into WTAs.
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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) | 0.001 | 0.001 |
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".