An Iron-Containing Dodecameric Heptosyltransferase Family Modifies Bacterial Autotransporters in Pathogenesis
Qiuhe Lu, Qing Yao, Yue Xu, Lin Li, Shan Li, Yanhua Liu, Wenqing Gao, Miao Niu, Michal Sharon, Gili Ben-Nissan, Alla Zamyatina, Xiaoyun Liu, She Chen, Feng Shao
Research output: Contribution to journal › Article › peer-review
Autotransporters deliver virulence factors to the bacterial surface by translocating an effector passenger domain through a membrane-anchored barrel structure. Although passenger domains are diverse, those found in enteric bacteria autotransporters, including AIDA-I in diffusely adhering Escherichia coli (DAEC) and TibA in enterotoxigenic E. coli, are commonly glycosylated. We show that AIDA-I is heptosylated within the bacterial cytoplasm by autotransporter adhesin heptosyltransferase (AAH) and its paralogue AAH2. AIDA-I heptosylation determines DAEC adhesion to host cells. AAH/AAH2 define a bacterial autotransporter heptosyltransferase (BAHT) family that contains ferric ion and adopts a dodecamer assembly. Structural analyses of the heptosylated TibA passenger domain reveal 35 heptose conjugates forming patterned and solenoid-like arrays on the surface of a beta helix. Additionally, CARC, the AIDA-like autotransporter from Citrobacter rodentium, is essential for colonization in mice and requires heptosylation by its cognate BAHT. Our study establishes a bacterial glycosylation system that regulates virulence and is essential for pathogenesis.