M13 procoat protein insertion into YidC and SecYEG proteoliposomes and liposomes

J Mol Biol. 2011 Feb 25;406(3):362-70. doi: 10.1016/j.jmb.2010.12.036. Epub 2010 Dec 30.


M13 procoat protein was one of the first model proteins used to study bacterial membrane protein insertion. It contains a signal peptide of 23 amino acid residues and is not membrane targeted by the signal recognition particle. The translocation of its periplasmic domain is independent of the preprotein translocase (SecAYEG) but requires electrochemical membrane potential and the membrane insertase YidC of Escherichia coli. We show here that YidC is sufficient for efficient membrane insertion of the purified M13 procoat protein into energized YidC proteoliposomes. When no membrane potential is applied, the insertion is substantially reduced. Only in the presence of YidC, membrane insertion occurs if bilayer integrity is preserved and membrane potential is stable for more than 20 min. A mutant of the M13 procoat protein, H5EE, with two additional negatively charged residues in the periplasmic domain inserted into YidC proteoliposomes and SecYEG proteoliposomes with equal efficiencies. We conclude that the protein can use both the YidC-only pathway and the Sec pathway. This poses the questions of how procoat H5EE is inserted in vivo and how insertion pathways are selected in the cell.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Capsid Proteins* / chemistry
  • Capsid Proteins* / genetics
  • Capsid Proteins* / metabolism
  • Escherichia coli
  • Escherichia coli Proteins* / chemistry
  • Escherichia coli Proteins* / genetics
  • Escherichia coli Proteins* / metabolism
  • Liposomes*
  • Membrane Transport Proteins* / chemistry
  • Membrane Transport Proteins* / genetics
  • Membrane Transport Proteins* / metabolism
  • Mutation
  • Periplasm / chemistry
  • Protein Sorting Signals / genetics
  • Protein Transport
  • Proteolipids*
  • SEC Translocation Channels
  • Signal Recognition Particle / genetics
  • Signal Recognition Particle / metabolism


  • Capsid Proteins
  • Escherichia coli Proteins
  • Liposomes
  • Membrane Transport Proteins
  • Protein Sorting Signals
  • Proteolipids
  • SEC Translocation Channels
  • Signal Recognition Particle
  • YIDC protein, E coli
  • coat protein, Bacteriophage M13
  • proteoliposomes