The essential Escherichia coli msbA gene, a multicopy suppressor of null mutations in the htrB gene, is related to the universally conserved family of ATP-dependent translocators

Mol Microbiol. 1993 Jan;7(1):69-79. doi: 10.1111/j.1365-2958.1993.tb01098.x.


We report the characterization of the msbA gene, isolated as a multicopy suppressor of the HtrB temperature-sensitive phenotype. The msbA gene maps to 20.5 min on the Escherichia coli genetic map and encodes a protein with an estimated molecular mass of 64,460 Da, with the properties of an integral membrane protein. The amino acid sequence of MsbA is very similar to those of the family of ATP-dependent translocators, which includes the haemolysin B protein of E. coli and the mammalian multidrug resistance (MDR) proteins. Mutational analysis of msbA indicates that it may form an operon with a downstream gene, orfE, and that both of these genes are essential for bacterial viability under all growth conditions tested.

Publication types

  • Comparative Study
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • ATP Binding Cassette Transporter, Subfamily B, Member 1
  • ATP-Binding Cassette Transporters*
  • Amino Acid Sequence
  • Bacterial Proteins / genetics*
  • Base Sequence
  • Biological Evolution
  • Carrier Proteins / genetics*
  • Escherichia coli / genetics*
  • Genes, Bacterial*
  • Genes, Lethal
  • Genes, Suppressor*
  • Genetic Complementation Test
  • Hemolysin Proteins
  • Membrane Glycoproteins / genetics
  • Membrane Proteins / genetics
  • Molecular Sequence Data
  • Multigene Family*
  • Phenotype
  • Sequence Alignment
  • Sequence Homology, Amino Acid


  • ATP Binding Cassette Transporter, Subfamily B, Member 1
  • ATP-Binding Cassette Transporters
  • Bacterial Proteins
  • Carrier Proteins
  • Hemolysin Proteins
  • Hlyb protein, Bacteria
  • Membrane Glycoproteins
  • Membrane Proteins
  • MsbA protein, Bacteria
  • hepA protein, Anabaena

Associated data

  • GENBANK/Z11796