title: Co-opting the cell wall in fighting methicillin-resistant Staphylococcus aureus: potent inhibition of PBP 2a by two anti-MRSA beta-lactam antibiotics.
abstract: Methicillin-resistant Staphylococcus aureus (MRSA) is a global bacterial scourge that has become resistant to many classes of antibiotics, and treatment options for MRSA infections are limited. The cause of MRSA resistance to all commercially available beta-lactam antibiotics is the acquisition of the gene mecA, which encodes penicillin-binding protein 2a (PBP 2a). PBP 2a is a transpeptidase, which in contrast to the other transpeptidases of S. aureus does not experience inhibition by beta-lactam antibiotics. The lack of inhibition is due to a closed conformation for the active site for PBP 2a, which opens up only in the course of the catalytic function of the protein. Here we show that two new anti-MRSA antibiotics now undergoing clinical trials, ceftaroline and ME1036, are able to inhibit PBP 2a effectively, a process that is enhanced in the presence of a cell wall structural surrogate. It is likely that in the course of bacterial growth the occupancy of the allosteric site for the cell wall is co-opted by these antibiotics, and under these conditions the second-order rate constant for the encounter of the antibiotic and PBP 2a approaches the clinically useful value of 10(4)-10(5) M-1 s-1. These compounds are potent inhibitors of PBP 2a as well as PBPs from other species, and have potential as therapeutic agents for treatment of serious infections by MRSA and other resistant bacterial pathogens.
authors.affiliation: Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, USA.
authors.forename: Adriel
authors.initials: A
authors.lastname: Villegas-Estrada
authors.forename: Mijoon
authors.initials: M
authors.lastname: Lee
authors.forename: Dusan
authors.initials: D
authors.lastname: Hesek
authors.forename: Sergei B
authors.initials: SB
authors.lastname: Vakulenko
authors.forename: Shahriar
authors.initials: S
authors.lastname: Mobashery
mesh_terms: D000117:Acetylglucosamine / Q000737:chemistry / Q000378:metabolism; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001665:Binding Sites; D040761:Biomimetic Materials / Q000737:chemistry / Q000378:metabolism; D015780:Carbapenems / Q000494:pharmacology*; D002473:Cell Wall / Q000378:metabolism; D002511:Cephalosporins / Q000494:pharmacology*; D002942:Circular Dichroism; D007700:Kinetics; D016106:Methicillin Resistance; D009112:Muramic Acids / Q000737:chemistry / Q000378:metabolism; D046915:Penicillin-Binding Proteins / Q000037:antagonists & inhibitors* / Q000737:chemistry; D010453:Peptide Synthases / Q000037:antagonists & inhibitors* / Q000737:chemistry; D010457:Peptidoglycan / Q000737:chemistry / Q000378:metabolism; D011487:Protein Conformation; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000201:enzymology* / Q000378:metabolism; D000097583:Ceftaroline
chemical_list: D000117:Acetylglucosamine; D000900:Anti-Bacterial Agents; D015780:Carbapenems; D002511:Cephalosporins; D009112:Muramic Acids; D046915:Penicillin-Binding Proteins; D010453:Peptide Synthases; D010457:Peptidoglycan; D000097583:Ceftaroline; C490527:ME1036; C478699:penicillin-binding protein 2a, Streptococcus; C031651:N-acetylmuramic acid