This domain is found at the N-terminal end of Glycosyltransferase TibC from Escherichia coli and similar bacterial. TibC is an autotransporter adhesin heptosyltransferase (AAH) homologue that catalyses the heptosylation of the autotransporters AIDA-I/TibA and confers AIDA-I-mediated bacterial adhesion to host cells. This domain adopts a beta-barrel fold with two four-stranded sheets that pack against each other [1,2].

1: A structural mechanism for bacterial autotransporter glycosylation by a dodecameric heptosyltransferase family. Yao Q, Lu Q, Wan X, Song F, Xu Y, Hu M, Zamyatina A, Liu X, Huang N, Zhu P, Shao F; Elife. 2014; [Epub ahead of print] PMID:25310236

2: Functional substitution of the TibC protein of enterotoxigenic Escherichia coli strains for the autotransporter adhesin heptosyltransferase of the AIDA system. Moormann C, Benz I, Schmidt MA; Infect Immun. 2002;70:2264-2270. PMID:11953358