The bacterial immunoglobulin-like (Ig) domain 1 or Big-1 domain is a domain of ~95 amino acids present in bacterial adhesion molecules of the intimin/invasin family, involved in pathogenicity, and YeeJ, a inverse autotransporter adhesin. The domain is named after the 3D structure of the domain in enteropathogenic Escherichia coli intimin and in Yersinia pseudotuberculosis invasin, which are both … expand

The bacterial immunoglobulin-like (Ig) domain 1 or Big-1 domain is a domain of ~95 amino acids present in bacterial adhesion molecules of the intimin/invasin family, involved in pathogenicity, and YeeJ, a inverse autotransporter adhesin. The domain is named after the 3D structure of the domain in enteropathogenic Escherichia coli intimin and in Yersinia pseudotuberculosis invasin, which are both adhesins with a tandem repeat of the Big-1 domain. The 3D structure of the Big-1 domain is a β-sheet sandwich with a topology similar to eukaryotic members of the immunoglobulin superfamily. In most intimin/invasin proteins the Big-1 domain occurs in a tandem, N-terminal to a different Ig-like domain, followed by a C-terminal C-type lectin-like domain. Big-1 can also occur in combination with the lysM domain or in a tandem repeat of several copies.

Big-1 proteins are surface-expressed proteins that mediate mammalian host cell invasion or attachment. The tandem of Ig-like domains appears to form a rod to link the bacterial outer membrane anchor to the C-terminal lectin-like domain to interact with their receptors in the host cell membrane [ PUBMED:10201396 PUBMED:10514372 PUBMED:10890451 ].