Streptococcus agalactiae GAPDH Is a Virulence-Associated Immunomodulatory Protein

Abstract

Certain extracellular proteins produced by several pathogenic microorganisms interfere with the host immune system facilitating microbial colonization and were thus designated virulence-associated immunomodulatory proteins. In this study, a protein with B lymphocyte stimulatory activity was isolated from culture supernatants of Streptococcus agalactiae strain NEM316. This protein, with an apparent molecular mass of 45 kDa, was identified as GAPDH by N-terminal amino acid sequencing. The gapC gene was cloned and expressed in Escherichia coli for the production of a recombinant histidyl-tagged protein. The recombinant GAPDH (rGAPDH), purified in an enzymatically active form, induced in vitro an up-regulation of CD69 expression on B cells from normal and BCR transgenic mice. In addition, rGAPDH induced an increase in the numbers of total, but not of rGAPDH-specific, splenic Ig-secreting cells in C57BL/6 mice treated i.p. with this protein. These in vitro- and in vivo-elicited B cell responses suggest that the B cell stimulatory effect of rGAPDH is independent of BCR specificity. A S. agalactiae strain overexpressing GAPDH showed increased virulence as compared with the wild-type strain in C57BL/6 mice. This virulence was markedly reduced in IL-10-deficient and anti-rGAPDH antiserum-treated mice. These results suggest that IL-10 production, which was detected at higher concentrations in the serum of rGAPDH-treated mice, is important in determining the successfulness of the host colonization by S. agalactiae and they highlight the direct role of GAPDH in this process. Taken together, our data demonstrate that S. agalactiae GAPDH is a virulence-associated immunomodulatory protein.

Interaction with human plasminogen system turns on proteolytic activity in Streptococcus agalactiae and enhances its virulence in a mouse model

“…We have recently showed that GAPDH is a virulenceassociated protein [19]. In the present study, we identified this enzyme as one of the GBS plasminogen binding protein.…”

“…In the present report, we provide the first evidence for the acquisition of surface plasmin-like activity by GBS and we further demonstrate the role of surface-bound Plg in bacterial invasiveness and virulence. We have recently described that GBS GAPDH is a virulence-associated immunomodulatory protein [19] and we show here that this enzyme is also one of the GBS Plg-binding proteins.…”

“…Enzymatically active His-tagged recombinant GBS GAPDH (rGADPH) was produced from Escherichia coli BL21 (lDE3) harbouring pET28aUgapC as described previously [19]. S. agalactiae sonicates, rGAPDH, and Plg (positive control) were subjected to SDS-PAGE (10% polyacrylamide) and transferred to nitrocellulose membrane (Amersham Biosciences, Uppsala, Sweden).…”

Characterization of pyruvate dehydrogenase subunit B and enolase as plasminogen-binding proteins in Mycoplasma pneumoniae

“…This includes protection against the host's immune response, as described for Streptococcus spp. (Feng et al, 2009;Madureira et al, 2007), adherence to deeper layers of epithelium showing higher concentrations of ECM molecules (Yavlovich et al, 2004), and access of the bacteria to more favourable nutrient conditions.…”

Role of Mycoplasma pneumoniae glyceraldehyde-3-phosphate dehydrogenase (GAPDH) in mediating interactions with the human extracellular matrix

“…Here, the lack of inhibition of the adherence process of M. pneumoniae to HeLa cells by polyclonal anti-GAPDH serum suggests a limited influence on the primary adhesion process, which is mediated mainly by the characterized adhesins of the tip structure. After this first step, the gliding motility of the mycoplasmas (Miyata, 2010) allows movement to deeper layers of the respiratory epithelium, where higher concentrations of ECM proteins provide the bacterium with a nutrient-rich environment and/or partial protection from the host's immune response (Madureira et al, 2007).…”