PatA and PatB Form a Functional Heterodimeric ABC Multidrug Efflux Transporter Responsible for the Resistance of Streptococcus pneumoniae to Fluoroquinolones
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- 作者：Emilie Boncoeur ; Claire Durmort ; Beno卯t Bernay ; Christine Ebel ; Anne Marie Di Guilmi ; Jacques Croiz茅 ; Thierry Vernet ; Jean-Michel Jault
- 刊名：Biochemistry
- 出版年：2012
- 出版时间：October 2, 2012
- 年：2012
- 卷：51
- 期：39
- 页码：7755-7765
- 全文大小：458K
- 年卷期：v.51,no.39(October 2, 2012)
- ISSN：1520-4995
文摘
All bacterial multidrug ABC transporters have been shown to work as either homodimers or heterodimers. Two possibly linked genes, patA and patB from Streptococcus pneumococcus, that encode half-ABC transporters have been shown previously to be involved in fluoroquinolone resistance. We showed that the 螖patA, 螖patB, or 螖patA/螖patB mutant strains were more sensitive to unstructurally related compounds, i.e., ethidium bromide or fluoroquinolones, than the wild-type R6 strain. Inside-out vesicles prepared from Escherichia coli expressing PatA and/or PatB transported Hoechst 33342, a classical substrate of multidrug transporters, only when both PatA and PatB were coexpressed. This transport was inhibited either by orthovanadate or by reserpine, and mutation of the conserved Walker A lysine residue of either PatA or PatB fully abrogated Hoechst 33342 transport. PatA, PatB, and the PatA/PatB heterodimer were purified from detergent-solubilized E. coli membrane preparations. Protein dimers were identified in all cases, albeit in different proportions. In contrast to the PatA/PatB heterodimers, homodimers of PatA or PatB failed to show a vanadate-sensitive ATPase activity. Thus, PatA and PatB need to interact together to make a functional drug efflux transporter, and they work only as heterodimers.