An Iron-Containing Dodecameric Heptosyltransferase Family Modifies Bacterial Autotransporters in Pathogenesis

Subjects: Biology >> Biophysics submitted time 2016-05-18

Lu, Qiuhe Yao, Qing Xu, Yue Li, Lin Li, Shan Gao, Wenqing Niu, Miao Chen, She Shao, Feng Xu, Yue Liu, Yanhua Liu, Xiaoyun Liu, Yanhua Liu, Xiaoyun Sharon, Michal Ben-Nissan, Gili Zamyatina, Alla Shao, Feng Shao, Feng

Abstract： 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.

Peer Review Status:Awaiting Review

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