Mechanism of <i>Staphylococcus aureus</i> peptidoglycan <i>O</i> -acetyltransferase A as an <i>O</i> -acyltransferase
Carys S. Jones, Alexander C. Anderson, Anthony J. Clarke
Abstract
Significance Enzymes comprised of membrane-spanning acyltransferase-3 (AT-3) domains catalyze the O-acetylation of diverse extracytoplasmic glycans in all forms of life. In many cases, such as peptidoglycan, these glycans represent important cell wall components, and their O-acetylation confers resistance to lytic enzymes. The enzyme responsible for peptidoglycan O-acetylation in gram-positive bacteria, OatA, is a single bimodal protein of an AT-3 domain fused to an SGNH domain. The AT-3 domain adopts a different topology to that predicted in silico. Moreover, its utilization of a unique mechanism for the translocation of acetyl groups across the cytoplasmic membrane for their transfer to peptidoglycan involving catalytic Tyr and Ser residues may be broadly applicable to homologs involved in the modification of other important cell wall glycans.