Protein Family Models

The cariogenic bacterium Streptococcus mutans uses adhesin P1 to adhere to tooth surfaces, extracellular matrix components, and other bacteria. The N terminus forms a stabilizing scaffold by wrapping behind the base of P1's elongated stalk and physically 'locking' it into place. It is suggested that the N-terminal has such a pronounced impact on P1 immunogenicity, antigenicity, folding, stability, and adherent function [1]. [1]. 25331888. An intramolecular lock facilitates folding and stabilizes the. tertiary structure of Streptococcus mutans adhesin P1.. Heim KP, Crowley PJ, Long JR, Kailasan S, McKenna R, Brady LJ;. Proc Natl Acad Sci U S A. 2014;111:15746-15751. (from Pfam)

Date:

2024-08-14

This repeated domain is found at the C-terminus of cell surface antigens [1-3]. In the Streptococcus mutans antigen I/II there are three repeats of this domain, a cleft between the first two of these forms a binding site for the human salivary agglutinin (SAG) [3]. [1]. 12485987. A novel variant of the immunoglobulin fold in surface adhesins. of Staphylococcus aureus: crystal structure of the. fibrinogen-binding MSCRAMM, clumping factor A.. Deivanayagam CC, Wann ER, Chen W, Carson M, Rajashankar KR, Hook. M, Narayana SV;. EMBO J. 2002;21:6660-6672.. [2]. 20138058. Two intramolecular isopeptide bonds are identified in the. crystal structure of the Streptococcus gordonii SspB C-terminal. domain.. Forsgren N, Lamont RJ, Persson K;. J Mol Biol. 2010;397:740-751.. [3]. 21505225. Crystal structure of the C-terminal region of Streptococcus. mutans antigen I/II and characterization of salivary agglutinin. adherence domains.. Larson MR, Rajashankar KR, Crowley PJ, Kelly C, Mitchell TJ,. Brady LJ, Deivanayagam C;. J Biol Chem. 2011;286:21657-21666. (from Pfam)

Date:

2024-08-14

This is the second domain (C2) located in the C-terminal region found in antigen I/II type adhesin protein AspA from S. pyogenes. Together with C3, these two domains form an elongated structure, each domain adopts the DEv-IgG fold. Similar to the classical IgG folds, it is comprised of two major antiparallel beta-sheets, designated ABED and CFG. For the C2-domain, there are two additional strands on the CFG sheet. Furthermore, sheets ABED and CFG are interconnected by several cross-connecting loops and one alpha-helix (DH1). The side chains of D982 and N996 in the C2-domain are involved in hydrogen bonding with the side chains of R1264 and N1295 in the C3 domain. Main chain hydrogen bonding can also be observed between S992 in C2 and N1189/G1191 in C3, furthermore stabilizing the interaction between the domains. The C2 domain contains one bound metal ion, modeled as Ca2+, and both the C2- and C3-domains are stabilized by conserved isopeptide bonds, which connect the beta-sheets of the central DEv-IgG motifs [1].Other members of this family include Major cell-surface adhesin PAc from Streptococcus mutans and SspB from Streptococcus gordonii. [1]. 24918040. Structure of the C-terminal domain of AspA (antigen I/II-family). protein from Streptococcus pyogenes.. Hall M, Nylander S, Jenkinson HF, Persson K;. FEBS Open Bio. 2014;4:283-289. (from Pfam)

Date:

2024-08-14

This domain is found in the Streptococcus Glucan-binding protein C (GbpC) and also in surface protein antigen (Spa)-family proteins which show sequence similarity to GbpC [1]. [1]. 9009329. Cloning and sequence analysis of the gbpC gene encoding a novel. glucan-binding protein of Streptococcus mutans.. Sato Y, Yamamoto Y, Kizaki H;. Infect Immun 1997;65:668-675. (from Pfam)

Date:

2024-08-14

This family consists of a number of ~25 residue long repeats found commonly in Streptococcal surface antigens although one copy is present in the HPSR2-heavy chain potential motor protein of Giardia lamblia (Swiss:Q24984). This family is often found in conjunction with Pfam:PF00746. (from Pfam)

Date:

2024-08-14

Date:

2024-08-14

This domain has a conserved Lys (position 3 in seed alignment) and Asn at 177 that form an intramolecular isopeptide bond. The Asp (or Glu) at position 59, first position of the motif DDYDQ, forms hydrogen bonds to moieties in the isopeptide bond.

Date:

2023-11-14

The YSIRK signal domain targets proteins to the cross-wall, or septum, of dividing Gram-positive bacterial. Lipoprotein signal motifs direct a characteristic N-terminal cleavage and lipid modification for membrane anchoring. This Streptococcal-only signal peptide variant appears to be a hybrid between the two, likely directing protein targeting of nascent surface lipoproteins to the cross-wall. Nearly all members of this family have the characteristic LPXTG cell wall anchor signal at the C-terminus. Member proteins include adhesin SspB, adhesin SspS, and cell surface antigen I/II.

Date:

2023-11-15