Role of M protein in adherence of group A streptococci.
The role of the M protein in adherence of group A streptococci to human epithelial cells was directly tested by using an isogenic pair of M+ and M- strains. There was no difference between these strains in the number of streptococcal units that adhered to buccal or tonsillar epithelial cells, indicating the following: (i) that adhesins that are not dependent upon M protein expression are present on the surface of group A streptococci and (ii) that the M protein is not the primary streptococcal adherence ligand. However, the M+ strain adhered to tonsillar epithelial cells as aggregates. This aggregation was dependent on the presence of the M protein, since the isogenic M- strain did not clump. The coaggregation of streptococci suggests that the M protein plays an important role in promoting the formation of microcolonies after initial attachment. Binding to fibronectin, a potential epithelial cell receptor for group A streptococci, was also the same for the isogenic M+ and M- strains as well as for an isogenic strain with a regulatory mutation that decreases the expression of M protein. In summary, the M protein is not the primary streptococcal adhesin, nor is it required to orient the streptococcal adhesin and/or fibronectin receptor.
Caparon
M G
MG
Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri 63110.
Stephens
D S
DS
Olsén
A
A
Scott
J R
JR
D000942:Antigens, Bacterial; D001422:Bacterial Adhesion; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins / Q000633:toxicity*; D002352:Carrier Proteins; D005353:Fibronectins / Q000502:physiology; D006801:Humans; D008070:Lipopolysaccharides / Q000633:toxicity; D009061:Mouth Mucosa / Q000382:microbiology; D009924:Organ Culture Techniques; D014066:Palatine Tonsil / Q000382:microbiology; D013297:Streptococcus pyogenes / Q000472:pathogenicity / Q000502:physiology*; D013682:Teichoic Acids / Q000633:toxicity
D000942:Antigens, Bacterial; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D002352:Carrier Proteins; D005353:Fibronectins; D008070:Lipopolysaccharides; D013682:Teichoic Acids; C014689:streptococcal M protein; C009900:lipoteichoic acid