Analysis of the membrane organization of an Escherichia coli protein translocator, HlyB, a member of a large family of prokaryote and eukaryote surface transport proteins

J Mol Biol. 1991 Feb 5;217(3):441-54. doi: 10.1016/0022-2836(91)90748-u.


Haemolysin B (HlyB) is essential for secretion of the 107 x 10(3) Mr haemolysin A protein from Escherichia coli and is a member of a family of highly conserved, apparently ATP-dependent surface proteins in many organisms. We have shown in this study that both HlyB and HlyD fractionate primarily with the cytoplasmic membrane of E. coli and are accessible to proteases after removal of the outer membrane. We have measured experimentally the topological organization of HlyB within the membrane by construction of fusions to beta-lactamase as a reporter. The predicted folding of HlyB, with a minimum of six transmembrane segments, does not always coincide with regions of highest average hydrophobicity. This suggests that HlyB may have a novel organization within the bilayer. From our data and comparative sequence analysis, we have been able to predict very similar topological models for the other members of the HlyB family.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Bacterial Proteins / chemistry
  • Bacterial Proteins / genetics*
  • Bacterial Proteins / metabolism
  • Bacterial Proteins / ultrastructure
  • Base Sequence
  • Biological Transport, Active
  • Cell Compartmentation
  • Cell Membrane / metabolism
  • Cloning, Molecular
  • Endopeptidases / pharmacology
  • Hemolysin Proteins / metabolism*
  • Membrane Proteins / chemistry
  • Membrane Proteins / genetics
  • Membrane Proteins / metabolism*
  • Membrane Proteins / ultrastructure
  • Molecular Sequence Data
  • Molecular Weight
  • Recombinant Fusion Proteins
  • Solubility


  • Bacterial Proteins
  • Hemolysin Proteins
  • Membrane Proteins
  • Recombinant Fusion Proteins
  • Endopeptidases