Two-component bacterial multidrug transporter, EbrAB: Mutations making each component solely functional |
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Authors: | Takashi Kikukawa Toshifumi Nara Seiji Miyauchi |
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Institution: | a Laboratory of Biomolecular Systems, Creative Research Initiative “Sosei” (CRIS), Hokkaido University, Sapporo 001-0021, Japan b Graduate School of Pharmaceutical Sciences, Hokkaido University, Sapporo 060-0812, Japan |
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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. |
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Keywords: | EbrAB EmrE Smr Ion-coupled transporter Multidrug resistance |
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