title: Two-component bacterial multidrug transporter, EbrAB: Mutations making each component solely functional.
abstract: EbrAB in Bacillus subtilis belongs to a novel small multidrug resistance (SMR) family of multidrug efflux pumps. EmrE in Escherichia coli, a representative of SMR, functions as a homo-oligomer in the membrane. On the other hand, EbrAB requires a hetero-oligomeric configuration consisting of two polypeptides, EbrA and EbrB. Although both polypeptides have a high sequence similarity, expression of either single polypeptide does not confer the multidrug-resistance. We performed mutation studies on EbrA and B to determine why EbrAB requires the hetero-oligomerization. Mutants of EbrA and B lacking both the hydrophilic loops and the C-terminus regions conferred the multidrug-resistance solely by each protein. This suggests that the hydrophilic loops and the C-terminus regions constrain them to their respective conformations upon the formation of the functional hetero-oligomer.
authors.affiliation: Laboratory of Biomolecular Systems, Creative Research Initiative Sosei (CRIS), Hokkaido University, Sapporo 001-0021, Japan. kikukawa@cast.hokudai.ac.jp
authors.forename: Takashi
authors.initials: T
authors.lastname: Kikukawa
authors.forename: Toshifumi
authors.initials: T
authors.lastname: Nara
authors.forename: Tsunehisa
authors.initials: T
authors.lastname: Araiso
authors.forename: Seiji
authors.initials: S
authors.lastname: Miyauchi
authors.forename: Naoki
authors.initials: N
authors.lastname: Kamo
mesh_terms: D000595:Amino Acid Sequence; D001412:Bacillus subtilis / Q000378:metabolism*; D001483:Base Sequence; D002352:Carrier Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017931:DNA Primers; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000378:metabolism*; D004996:Ethidium / Q000378:metabolism; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D009154:Mutation; D004364:Pharmaceutical Preparations / Q000378:metabolism*; D010957:Plasmids; D017386:Sequence Homology, Amino Acid
chemical_list: D002352:Carrier Proteins; D017931:DNA Primers; D004364:Pharmaceutical Preparations; D004996:Ethidium