Fluoroquinolone efflux by the plasmid-mediated multidrug efflux pump QacB variant QacBIII in Staphylococcus aureus.

ABSTRACT: Plasmids that carry the multidrug efflux genes qacA and qacB are widely distributed in methicillin-resistant Staphylococcus aureus (MRSA). Although the QacA and QacB proteins are similar to each other, their respective substrate specificities may differ. We investigated the variability and structure-function relationships of QacA and QacB in MRSA isolates. The amino acid sequences of 7 QacA and 25 QacB proteins showed that QacB was present in three variants, designated QacBII, QacBIII, and QacBIV, that were different from the prototypic QacB variant encoded by plasmid pSK23, which was named QacBI, while QacA was present in two variants. When cloned and expressed in S. aureus, the strain carrying qacBIII exhibited higher susceptibility to dyes and decreased susceptibility to norfloxacin and

SUBMITTER: Nakaminami H 

PROVIDER: S-EPMC2944592 | biostudies-literature | 2010 Oct

REPOSITORIES: biostudies-literature