O-Acetylation of the N-acetylmuramic acid residue of peptidoglycan (PG) prevents the hydrolysis of the cell wall by autolysins and muramidases and is an important virulence factor in many bacteria. O-Acetylated PG aids in the survival of these bacteria within the host environment while preventing detection and clearance. O-Acetyltransferase A (OatA) has been identified as the enzyme responsible for this modification in Gram-positive bacteria. This study aims to expand our understanding of the O-acetylation of PG, and identify inhibitors of OatA from S. aureus to demonstrate OatA as a potential antibacterial target. Presented here are the kinetic parameters of pseudo-substrate donors and the first direct evidence of a Ser-His-Asp catalytic center of OatA. High-throughput screening has led to the identification of a class of compounds, coumarins, which show promising inhibitory properties in vitro. This research represents the first steps in providing evidence that OatA is a prospective pharmacological target.