A host-inducible cytochrome P-450 from a host-specific caterpillar: Molecular cloning and evolution

Michael B. Cohen, Mary A Schuler, May R Berenbaum

Research output: Contribution to journalArticle


Cytochrome P-450 monooxygenases (P-450s) play a critical role in the detoxification of natural and synthetic toxins in a wide range of organisms. We have isolated and sequenced cDNA clones encoding a P-450, CYP6B1, from larvae of Papilio polyxenes (Lepidoptera: Papilionidae), the black swallowtail butterfly. This P-450, cloned from a herbivorous insect, is highly inducible by xanthotoxin, a secondary metabolite abundant in the host plants of this specialized herbivore. On Northern blots, mRNAs crossreactive with CYP6B1 were detected in three Papilio species that, like the black swallowtail, have high levels of xanthotoxin-metabolic P-450 activity and encounter xanthotoxin or related compounds in their host plants; in contrast, no crossreactive mRNAs were detectable in three papilionid species that never encounter xanthotoxin in their host plants and lack detectable xanthotoxin-metabolic activity. These results provide evidence that new P-450s can arise as herbivores colonize different host plants and support the hypothesis that interactions between herbivores and their toxin-producing host plants have contributed to the diversification of the P-450 superfamily.

Original languageEnglish (US)
Pages (from-to)10920-10924
Number of pages5
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number22
StatePublished - Jan 1 1992


  • Insect P-450 monooxygenase cDNA
  • Xanthotoxin

ASJC Scopus subject areas

  • General

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