Project Title: Inhibition of Staphylococcus aureus cell wall remodeling
Project Code: J1-8192
Participating groups: Dusan Turk (IJS, CIPKEBIP), Marjana Novic (KI), Marko Anderluh (FFA)
The wide-spread use of antibiotics is resulting in increasing number of antibiotic and multiple antibiotic resistant strains. Among them are the MRSA (methicillin resistant Staphylococcus aureus) and VRSA (vancomycin resistant Staphylococcus aureus). Treatment of such infections is difficult and it urgently calls for new approaches in drug discovery that in turn requires novel insight. Gene knockout and our recent and preliminary studies of S. aureus N-acetyl-glucosaminidases from GH 73 family suggest that these enzymes may indeed play a major role in remodeling of bacterial peptidoglycan cell wall and in formation of biofilm. Our project goal is to validate the drug target potential of N-acetylglucosaminidases from GH 73 family in treatment of S. aureus infections. During the process we will gain novel insight and understanding of the mechanisms underlying remodeling of the peptidoglycan cell wall of S. aureus and their biofilms. We will study all five members encoded in genome of Staphylococcus aureus Mu50 of the family by complementary approaches of molecular biology, crystal structure analysis, enzyme kinetics, virtual screening based and classical inhibitor design synthesis, biochemical and mass spectroscopy analysis, and by microscopic observation of bacterial planctonic and biofilm cultures (including naturally occurring bacteria and those impaired by knockouts). We believe that research systematically addressing the whole family of N-acetylglucosaminidases together has the potential to deliver fundamental discoveries about their roles in cell wall remodeling and biofilm formation. Analysis of crystal structure of glucosaminidases from GH 73 family shows substantial differences in the active site cleft. In contrast, the sequence homology of glucosaminidase domains of GH 73 enzymes from S. aureus shows that the residues in the active site are homologues. This suggests that it may be possible to develop an inhibitor that will inhibit only enzymes from S. aureus. Hence, a successful validation of N-acetylglucosaminidases from S. aureus as drug targets opens a perspective to develop drugs that will in a species specific manner treat S. aureus infections and thereby reduce risks of wide spread resistance. In addition, a success in design and synthesis of compounds hampering the whole family of enzymes may deliver new drug prototypes. To conclude, successful outcome will deliver results contributing to novel drug discovery programs and has potential improve human healthcare in life threatening situations of infections with antibiotic resistance strains of S. aureus.