Autolysin mediated adherence of Staphylococcus aureus with Fibronectin, Gelatin and Heparin

Major autolysin (Atl) of Staphylococcus aureusis a cell surface associated peptidoglycan hydrolase with amidase and glucosaminidase domains. Atl enzymes (amidase and glucosaminidase) are known to participate in biofilm formation and also can bind with host matrices. Earlier studies demonstrated the binding of Atlwithfibronectin, thrombospondin 1, vitronectin and heat shock cognate protein Hsc70. Here, we have shown, Atl mediates attachment of S.aureus to heparin and gelatine as well. The atl mutant strain demonstrated around 2.5 fold decreased adherence with fibronectin, gelatin and heparin coated microtiter plates. The microscopic studies confirmed the reduced binding of atl mutant with them compared to its parental wild type and complemented mutant strains. Amidase and glucosaminidase were expressed as N-terminal histidine tagged proteins from Escherichia coli, purified and refolded. We found refolded amidase bind with fibronectin, gelatin and heparin; whereas refolded glucosaminidase binds with only fibronectin and heparin but not gelatin. These results reemphasize Atl as one of the crucial proteins from Staphylococcus that facilitate their binding with multiple host cellular components during colonization and infection.