This entry contains atypical Rib (aRib) domains. These are found in a variety of bacterial cell surface proteins. These proteins share a conserved motif with the Rib domain (YPDXXD). The structure of the aRib domain has been solved from two proteins, the SrpA adhesin [1] and the GspB adhesin [2]. In these proteins this domain has been termed the unique domain due to its lack of similarity to any other known structures at the time. The aRib domain from SrpA has been shown to mediate a dimer interaction [1]. This family has been added to the E-set clan based on its similarity to the Rib domain, although it does not contain the Ig fold.

1: Structural Basis for Sialoglycan Binding by the Streptococcus sanguinis SrpA Adhesin. Bensing BA, Loukachevitch LV, McCulloch KM, Yu H, Vann KR, Wawrzak Z, Anderson S, Chen X, Sullam PM, Iverson TM; J Biol Chem. 2016;291:7230-7240. PMID:26833566

2: A structural model for binding of the serine-rich repeat adhesin GspB to host carbohydrate receptors. Pyburn TM, Bensing BA, Xiong YQ, Melancon BJ, Tomasiak TM, Ward NJ, Yankovskaya V, Oliver KM, Cecchini G, Sulikowski GA, Tyska MJ, Sullam PM, Iverson TM; PLoS Pathog. 2011;7:e1002112. PMID:21765814