Prophenoloxidase activation is not required for survival to microbial infections in Drosophila

EMBO Rep. 2006 Feb;7(2):231-5. doi: 10.1038/sj.embor.7400592.


The antimicrobial defence of Drosophila relies on cellular and humoral processes, of which the inducible synthesis of antimicrobial peptides has attracted interest in recent years. Another potential line of defence is the activation, by a proteolytic cascade, of phenoloxidase, which leads to the production of quinones and melanin. However, in spite of several publications on this subject, the contribution of phenoloxidase activation to resistance to infections has not been established under appropriate in vivo conditions. Here, we have isolated the first Drosophila mutant for a prophenoloxidase-activating enzyme (PAE1). In contrast to wild-type flies, PAE1 mutants fail to activate phenoloxidase in the haemolymph following microbial challenge. Surprisingly, we find that these mutants are as resistant to infections as wild-type flies, in the total absence of circulating phenoloxidase activity. This raises the question with regard to the precise function of phenoloxidase activation in defence, if any.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Bacterial Infections / immunology*
  • Catechol Oxidase / genetics
  • Catechol Oxidase / immunology
  • Catechol Oxidase / metabolism*
  • Drosophila / enzymology*
  • Drosophila / genetics
  • Drosophila / immunology*
  • Drosophila / metabolism
  • Drosophila / microbiology*
  • Drosophila Proteins / immunology
  • Drosophila Proteins / metabolism*
  • Enzyme Activation
  • Enzyme Precursors / genetics
  • Enzyme Precursors / immunology
  • Enzyme Precursors / metabolism*
  • Gram-Negative Bacteria / immunology
  • Gram-Positive Bacteria / immunology
  • Hemolymph / immunology
  • Immunity, Innate
  • Mutation
  • Survival Rate


  • Drosophila Proteins
  • Enzyme Precursors
  • pro-phenoloxidase
  • Catechol Oxidase