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Shared Functional Attributes between the mecA Gene Product of Staphylococcus sciuri and Penicillin-Binding Protein 2a of Methicillin-Resistant Staphylococcus aureus

2007; American Chemical Society; Volume: 46; Issue: 27 Linguagem: Inglês

10.1021/bi7004587

1943-295X

Cosimo Fuda, Maxim Suvorov, Qicun Shi, Dušan Hesek, Mijoon Lee, Shahriar Mobashery,

Bacterial biofilms and quorum sensing

The genome of Staphylococcus aureus is constantly in a state of flux, acquiring genes that enable the bacterium to maintain resistance in the face of antibiotic pressure. The acquisition of the mecA gene from an unknown origin imparted S. aureus with broad resistance to β-lactam antibiotics, with the resultant strain designated as methicillin-resistant S. aureus (MRSA). Epidemiological and genetic evidence suggests that the gene encoding PBP 2a of MRSA might have originated from Staphylococcus sciuri, an animal pathogen, where it exists as a silent gene of unknown function. We synthesized, cloned, and expressed the mecA gene of S. sciuri in Escherichia coli, and the protein product was purified to homogeneity. Biochemical characterization and comparison of the protein to PBP 2a of S. aureus revealed them to be highly similar. These characteristics start with sequence similarity but extend to biochemical behavior in inhibition by β-lactam antibiotics, to the existence of an allosteric site for binding of bacterial peptidoglycan, to the issues of the sheltered active site, and to the need for conformational change in making the active site accessible to the substrate and the inhibitors. Altogether, the evidence strongly argues that the kinship between the two proteins is deep-rooted on the basis of many biochemical attributes quantified in this study.