Cleavage of colicin D is necessary for cell killing and requires the inner membrane peptidase LepB

Mol Cell. 2001 Jul;8(1):159-68. doi: 10.1016/s1097-2765(01)00276-3.


Colicin D is known to kill target cells by cleaving tRNA(Arg). A colicin D-resistant mutant was selected that was altered in the inner membrane leader peptidase, LepB. The substituted residue (Asn274Lys) is located close to the catalytic site. The mutation abolishes colicin D cleavage but not the processing of exported proteins. LepB is required for colicin D cleavage, releasing a small C-terminal fragment that retains full tRNase activity. The immunity protein was found to prevent colicin D processing and furthermore masks tRNase activity, thus protecting colicin D against LepB-mediated cleavage during export. Catalytic colicins share a consensus sequence at their putative processing site. Mutations affecting normal processing of colicin D abolish cytotoxicity without affecting the in vitro tRNase activity.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism
  • Blotting, Northern
  • Catalytic Domain
  • Colicins / chemistry
  • Colicins / genetics
  • Colicins / metabolism*
  • Colicins / pharmacology
  • Escherichia coli / physiology
  • Genetic Complementation Test
  • Membrane Proteins*
  • Models, Molecular
  • Molecular Sequence Data
  • Point Mutation
  • Protein Structure, Tertiary
  • Pyocins / metabolism
  • RNA, Transfer / metabolism
  • Ribonucleases / chemistry
  • Ribonucleases / genetics
  • Ribonucleases / metabolism*
  • Sequence Alignment
  • Serine Endopeptidases / genetics
  • Serine Endopeptidases / metabolism*
  • Temperature


  • Bacterial Proteins
  • Colicins
  • Membrane Proteins
  • Pyocins
  • RNA, Transfer
  • Ribonucleases
  • Serine Endopeptidases
  • type I signal peptidase