The Staphylococcus aureus esterase FmtA is essential for wall teichoic acid D-alanylation

Area of Science:

• Microbiology
• Molecular Biology
• Biochemistry

Background:

• * Staphylococcus aureus teichoic acids, including wall teichoic acids (WTAs) and lipoteichoic acids (LTAs), are crucial anionic glycopolymers.
• * Post-synthetic D-alanine (D-Ala) addition to these polymers regulates surface charge and pathogen survival.
• * Mechanisms controlling WTA D-alanylation are not fully understood, representing a significant knowledge gap.

Purpose of the Study:

• * To investigate the role of FmtA in the D-alanylation of Staphylococcus aureus teichoic acids.
• * To elucidate the relationship between LTA and WTA D-alanylation.
• * To understand how FmtA impacts bacterial surface properties and host interactions.

Main Methods:

• * Genetic inactivation of the fmtA gene in Staphylococcus aureus.
• * Analysis of D-Ala modification levels in WTA and LTA from wild-type and mutant strains.
• * Assessment of bacterial surface charge, adhesion, biofilm formation, and cell aggregation.

Main Results:

• * Inactivation of fmtA resulted in significantly reduced D-alanylation of WTA, while LTA D-alanylation remained normal.
• * fmtA mutants exhibited a more negative surface charge, decreased host cell adhesion, impaired biofilm formation, and altered cell aggregation.
• * These findings suggest LTA serves as the D-Ala donor for WTA modification, mediated by FmtA.

Conclusions:

• * FmtA is essential for the D-alanylation of wall teichoic acids in Staphylococcus aureus.
• * Lipoteichoic acid likely provides the D-alanine for WTA modification, a process dependent on FmtA.
• * Further research is needed to identify the acyltransferase responsible for incorporating D-Ala into WTA.