Protein Family Models

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]. 26833566. 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.. [2]. 21765814. 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. (from Pfam)

Date:

2024-08-14

This domain of bacterial surface proteins, about 80 amino acids long and often repeated 15 times or more in a protein sequence, is named for early described proteins such as Rib and alpha, but found in proteins with a wide variety of architectures and from various lineages.

Date:

2024-08-14

Date:

2024-08-14

This model describes the LPXTG motif-containing region found at the C-terminus of many surface proteins of Streptococcus and Streptomyces species. Cleavage between the Thr and Gly by sortase or a related enzyme leads to covalent anchoring at the new C-terminal Thr to the cell wall. Hits that do not lie at the C-terminus or are not found in Gram-positive bacteria are probably false-positive. A common feature of this proteins containing this domain appears to be a high proportion of charged and zwitterionic residues immediatedly upstream of the LPXTG motif. This model differs from other descriptions of the LPXTG region by including a portion of that upstream charged region.

Date:

2021-04-27

Sequences in this family are tandem repeats of about 79 amino acids, present in up to 14 copies in a protein and highly identical, even at the DNA level, within each protein. Sequences with these repeats are found in the Rib and alpha surface antigens of group B Streptococcus, Esp of Enterococcus faecalis, and related proteins of Lactobacillus. The repeat lacks Cys residues. Most members of this protein family also have the cell wall anchor motif LPXTG shared by many staphyloccal and streptococcal surface antigens.

Date:

2021-07-14