A single Photorhabdus gene, makes caterpillars floppy (mcf), allows Escherichia coli to persist within and kill insects

Proc Natl Acad Sci U S A. 2002 Aug 6;99(16):10742-7. doi: 10.1073/pnas.102068099. Epub 2002 Jul 22.


Photorhabdus luminescens, a bacterium with alternate pathogenic and symbiotic phases of its lifestyle, represents a source of novel genes associated with both virulence and symbiosis. This entomopathogen lives in a "symbiosis of pathogens" with nematodes that invade insects. Thus the bacteria are symbiotic with entomopathogenic nematodes but become pathogenic on release from the nematode into the insect blood system. Within the insect, the bacteria need to both avoid the peptide- and cellular- (hemocyte) mediated immune response and also to kill the host, which then acts as a reservoir for bacterial and nematode reproduction. However, the mechanisms whereby Photorhabdus evades the insect immune system and kills the host are unclear. Here we show that a single large Photorhabdus gene, makes caterpillars floppy (mcf), is sufficient to allow Esherichia coli both to persist within and kill an insect. The predicted high molecular weight Mcf toxin has little similarity to other known protein sequences but carries a BH3 domain and triggers apoptosis in both insect hemocytes and the midgut epithelium.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Apoptosis
  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism*
  • Bacterial Toxins / genetics
  • Bacterial Toxins / metabolism*
  • Base Sequence
  • Consensus Sequence
  • Cosmids / physiology*
  • DNA, Complementary
  • Digestive System / cytology
  • Escherichia coli / pathogenicity
  • Genes, Bacterial / physiology*
  • Hemocytes / cytology
  • Manduca / microbiology
  • Molecular Sequence Data
  • Open Reading Frames
  • Pest Control, Biological*
  • Photorhabdus* / genetics


  • Bacterial Proteins
  • Bacterial Toxins
  • DNA, Complementary

Associated data

  • GENBANK/AF503504