title: The YheI/YheH heterodimer from Bacillus subtilis is a multidrug ABC transporter.
abstract: ABC (ATP-binding cassette) transporters form the largest family of membrane proteins in micro-organisms where they are able to transport a wide variety of substrates against a concentration gradient, in an ATP-dependent process. Two genes from the same putative Bacillus subtilis operon, yheI and yheH, encoding possibly two different ABC transporters, were overexpressed in Escherichia coli in high yield, either separately or jointly. Using membrane vesicles, it is shown here that both subunits were required to detect, (i) the transport of four structurally unrelated drugs, and (ii) a vanadate-sensitive ATPase activity. Mutation of the invariant Walker-A lysine to an alanine residue in both subunits led to an inactive transporter. Moreover, after membrane solubilization by detergent, both wild-type subunits co-purified on a Ni-Agarose affinity column while only the YheH subunit contained a hexa-histidine tag. This shows that YheI and YheH are indeed able to interact together to form a heterodimer. Importantly, expression of both yheI and yheH genes in B. subtilis could be strongly stimulated by addition of sub-inhibitory concentrations of various unrelated antibiotics. Therefore, B. subtilis YheI/YheH forms a new heterodimeric multidrug ABC transporter possibly involved in multiple antibiotic resistance in vivo.
authors.affiliation: Institut de Biologie Structurale, UMR 5075 Université Joseph Fourier/CEA/CNRS, 41 rue Jules Horowitz 38027 Grenoble cedex 1, France.
authors.forename: Cristina
authors.initials: C
authors.lastname: Torres
authors.forename: Carmen
authors.initials: C
authors.lastname: Galián
authors.forename: Christoph
authors.initials: C
authors.lastname: Freiberg
authors.forename: Jean-Raphaël
authors.initials: JR
authors.lastname: Fantino
authors.forename: Jean-Michel
authors.initials: JM
authors.lastname: Jault
mesh_terms: D018435:ATP Binding Cassette Transporter, Subfamily B / Q000502:physiology*; D018528:ATP-Binding Cassette Transporters / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001412:Bacillus subtilis / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D019281:Dimerization; D009876:Operon
chemical_list: D018435:ATP Binding Cassette Transporter, Subfamily B; D018528:ATP-Binding Cassette Transporters; D000900:Anti-Bacterial Agents