The Plasmin-Sensitive Protein Pls in Methicillin-Resistant Staphylococcus aureus (MRSA) Is a Glycoprotein

Area of Science:

• Microbiology
• Glycobiology
• Bacterial Pathogenesis

Background:

• Protein glycosylation is crucial for bacterial virulence factors, but its role in Staphylococcus aureus remains unclear.
• Staphylococcus aureus, a major human pathogen, possesses complex glycosylation pathways impacting its pathogenicity.

Purpose of the Study:

• To investigate the impact of protein glycosylation on Staphylococcus aureus virulence.
• To identify glycosylated proteins and the enzymes responsible for their modification in MRSA.
• To elucidate the functional role of Pls glycosylation in bacterial behavior, particularly biofilm formation.

Main Methods:

• Analysis of methicillin-resistant Staphylococcus aureus (MRSA) lysates using SDS-PAGE and periodic acid-Schiff's staining.
• Mass spectrometry to identify glycosylated proteins, including plasmin-sensitive protein (Pls).
• Gene expression and deletion analyses to identify glycosyltransferases (GtfC, GtfD, SdgA, SdgB) involved in Pls glycosylation.

Main Results:

• Identified multiple glycosylated surface proteins in MRSA, with Pls being a major target.
• Discovered GtfC and GtfD, encoded on the SCCmec element, as key enzymes mediating Pls glycosylation at serine residues.
• Demonstrated that Pls glycosylation significantly enhances biofilm formation through distinct mechanisms, some involving eDNA.

Conclusions:

• Pls is a glycoprotein in Staphylococcus aureus, and its glycosylation is mediated by GtfC/GtfD and other enzymes.
• Pls glycosylation plays a critical role in stimulating biofilm formation, a key virulence factor.
• Targeting these sugar modifications offers potential for novel therapeutic and prophylactic strategies against S. aureus infections.