Structural and mechanistic basis of capsule O-acetylation in Neisseria meningitidis serogroup A

Abstract

Neisseria meningitidis capsular polysaccharide (CPS) is a major virulence factor and vaccine formulations against Neisseria meningitidis serogroup A (NmA) contain O-acetylated CPS. Here, the authors provide mechanistic insights into CPS O-acetylation in NmA by determining the crystal structure of the O-acetyltransferase CsaC and NMR measurements further reveal that the CsaC-mediated reaction is regioselective for O3 and that the O4 modification results from spontaneous O-acetyl migration.