Two-component bacterial multidrug transporter, EbrAB: Mutations making each component solely functional

Biochim Biophys Acta. 2006 May;1758(5):673-9. doi: 10.1016/j.bbamem.2006.04.004. Epub 2006 Apr 21.


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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Bacillus subtilis / metabolism*
  • Base Sequence
  • Carrier Proteins / chemistry
  • Carrier Proteins / genetics
  • Carrier Proteins / metabolism*
  • DNA Primers
  • Electrophoresis, Polyacrylamide Gel
  • Escherichia coli / metabolism*
  • Ethidium / metabolism
  • Microbial Sensitivity Tests
  • Molecular Sequence Data
  • Mutation*
  • Pharmaceutical Preparations / metabolism*
  • Plasmids
  • Sequence Homology, Amino Acid


  • Carrier Proteins
  • DNA Primers
  • Pharmaceutical Preparations
  • Ethidium