Streptococcus pyogenes antigen I/II‐family polypeptide AspA shows differential ligand‐binding properties and mediates biofilm formation

Abstract

The streptococcal antigen I/II (AgI/II)-family polypeptides are cell wall-anchored adhesins expressed by most indigenous oral streptococci. Proteins sharing 30–40% overall amino acid sequence similarities with AgI/II-family proteins are also expressed by Streptococcus pyogenes. The S. pyogenes M28_Spy1325 polypeptide (designated AspA) displays an AgI/II primary structure, with alanine-rich (A) and proline-rich (P) repeats flanking a V region that is projected distal from the cell. In this study it is shown that AspA from serotype M28 S. pyogenes, when expressed on surrogate host Lactococcus lactis, confers binding to immobilized salivary agglutinin gp-340. This binding was blocked by antibodies to the AspA-VP region. In contrast, the N-terminal region of AspA was deficient in binding fluid-phase gp-340, and L. lactis cells expressing AspA were not agglutinated by gp-340. Deletion of the aspA gene from two different M28 strains of S. pyogenes abrogated their abilities to form biofilms on saliva-coated surfaces. In each mutant strain, biofilm formation was restored by trans complementation of the aspA deletion. In addition, expression of AspA protein on the surface of L. lactis conferred biofilm-forming ability. Taken collectively, the results provide evidence that AspA is a biofilm-associated adhesin that may function in host colonization by S. pyogenes.

Structural and Functional Analysis of Cell Wall-anchored Polypeptide Adhesin BspA in Streptococcus agalactiae

“…Expression of BspA on the surface of L. lactis following nisin induction was confirmed by immuno-dot blot analysis ( Fig. 2A) with ␣-Spy1325mid antibodies to Streptococcus pyogenes AspA midregion (25), which shares 63% aa sequence identity across the corresponding VPC(473-990) region of BspA.…”

“…It has been proposed that genes carried within RD2 might contribute to both GAS and GBS pathogenicity (28,29). Supporting this, AspA has been shown to facilitate GAS biofilm formation on salivary pellicle (25), respiratory infection, and evasion of phagocytosis (30). Given this precedent, we hypothesized that Bsp polypeptides may serve as important host colonization determinants of GBS.…”

“…AgI/II family polypeptides have also been shown to promote microbial community development by binding to oral bacteria Actinomyces oris (19 -21) or Porphyromonas gingivalis (22,23), as well as to the pathogenic fungus Candida albicans (24). More recently, an AgI/II family polypeptide (group A Streptococcus surface protein, AspA) has been described in group A Streptococcus (GAS) (25). The gene encoding AspA is located within an integrative and conjugative element (ICE) designated region of difference 2 (RD2), which is found among GAS serotypes implicated in puerperal fever (26,27).…”

Physiological impact of transposable elements encoding DDE transposases in the environmental adaptation of Streptococcus agalactiae

“…In particular, the aggregation proteins expressed by these DDE conjugative transposons are related to the streptococcal antigen I/IIfamily protein (Guérillot et al, 2013). In streptococci, members of this family of adhesins have been shown to mediate attachment of the bacteria to host structures, to be involved in biofilm formation and host colonization, and to exert an immunomodulatory function (Brady et al, 2010;Maddocks et al, 2011).…”

Getting to the heart of the matter: Role ofStreptococcus mutansadhesin Cnm in systemic disease

“…One way to address this issue is to utilize a heterologous expression system and a successful strain for which there is precedent with Streptococcus proteins is Lactococcus lactis. [34][35][36][37][38] As a Gram-positive coccus, L. lactis shares many of the systems required for surface protein export and display and yet, as a dairy industry starter microorganism, it lacks capacity to interact strongly with human cells and tissues. 39 Consequently, L. lactis can serve as an excellent "blank canvas" with which gain of function can be explored following expression of a heterologous protein.…”