M protein mediates streptococcal adhesion to HEp-2 cells

Abstract

Streptococcus pyogenes adheres to human epithelial cells in vitro and in vivo. To identify adhesins, cell wall components were extracted from S. pyogenes M6 with alkali or by treatment with mutanolysin and lysozyme. HEp-2 cells were incubated with extracts of S. pyogenes M6 and then analyzed by Western blot (immunoblot) assays, using antibodies to S. pyogenes. Only one streptococcal component (62 kDa) was bound to HEp-2 cells and was identified serologically as M6 protein. Experiments with pepsin-cleaved fragments of M protein indicated that the binding site was located at the N-terminal half of the molecule. M protein was bound selectively to two trypsin-sensitive surface components, 97 and 205 kDa, of HEp-2 cells on nitrocellulose blots of sodium dodecyl sulfate-polyacrylamide gels. Tritium-labeled lipoteichoic acid bound to different HEp-2 cell components, 34 and 35 kDa, in a parallel experiment, indicating that lipoteichoic acid was not complexed with M protein and does not mediate M-protein binding. The four HEp-2 components were unrelated to fibronectin since they did not react with specific antibodies. An M-protein-deficient (M-) strain of streptococcus (JRS75), grown in chemically defined medium, showed 73% less adhesion activity to HEp-2 monolayers than an M+ strain (JRS4). Streptococcal adhesion was insensitive to competitive inhibition by selected monosaccharides. These results indicate that M protein binds directly to certain HEp-2 cell membrane components and mediates streptococcal adhesion.

De novo formation of focal complex‐like structures in host cells by invading Streptococci

“…M6 is the most abundant protein on the surface of JRS4, mediating GAS adherence to eukaryotic cells, but it is considerably less effective than protein F1 in mediating GAS entry into cells (Okada et al, 1994;Wang and Stinson, 1994;Jadoun et al, 1998;Berkower et al, 1999). In contrast to the polar distribution of protein F1, the distribution of M6 protein on the surface of the cocci chain was more homogeneous (compare Fig.…”

High‐frequency intracellular infection and erythrogenic toxin A expression undergo phase variation in M1 group A streptococci

“…Two variants of each type were analysed. The number of colony-forming units (cfu) from strains HW4 and HW8 decreased significantly during 3 h rotation in fresh phagocytic human blood ( High frequency invasion is not associated with more efficient adherence to A549 cells Adherence of some strains of group A streptococci to epithelial cells (Wang and Stinson, 1993) and keratinocytes (Okada et al, 1994) has been shown to require M protein. Experiments were performed to determine whether high-frequency internalization by LW variants relative to HW cultures reflected differences in their capacity to adhere to A549 cells.…”

Interactions between M proteins of Streptococcus pyogenes and glycosaminoglycans promote bacterial adhesion to host cells

“…The quantitatively dominating of these proteins, the M protein, has been traditionally regarded as a major virulence factor primarily through its ability to provide S. pyogenes with phagocytosis resistance [14,15]. However, the M protein is also likely to be involved in promoting bacterial adhesion to host tissue [16][17][18][19][20][21][22].…”