Molecular cloning and expression of CYP6B8: A xanthotoxin-inducible cytochrome P450 cDNA from Helicoverpa zea

Xianchun Li, May R. Berenbaum, Mary A. Schuler

Research output: Contribution to journalArticlepeer-review

104 Scopus citations


Xanthotoxin, a plant allelochemical, induces α-cypermethrin insecticide tolerance in Helicoverpa zea (corn earworm); inhibition of tolerance by piperonyl butoxide implicates cytochrome P450 monooxygenases (P4950s) in the detoxification of this insecticide. To characterize the xanthotoxin-inducible P450 that might mediate α-cypemethrin tolerance in this species, a cDNA library prepared from xanthotoxin-induced H. zea fifth instar larvae was screened with cDNAs encoding furanocoumarin-metabolizing P450s from Papilio polyxenes (CYP6B1v2) and P. glaucus (CYP6B4v2) as well as a sequence-related P450 from Helicoverpa armigera (CYP6B2). One full-length cDNA isolated in this screening shares 51-99% amino acid identity with the CYP6B subfamily of P450S isolated from Papilio and Helicoverpa species and, thus, has been designated CYP6B8. All of these CYP6B subfamily members share a number of highly conserved domains, including substrate recognition site 1 (SRS 1) that is critical for xanthotoxin metabolism by CYP6B 1 v2 from Papilio polyxenes and coumarin metabolism by CYP2a5 from Mus musculus. Northern and RT-PCR analyses indicate that CYP6B8 expression is strongly induced by xanthotoxin and phenobarbital and negligibly induced by α-cypermethrin.

Original languageEnglish (US)
Pages (from-to)75-84
Number of pages10
JournalInsect Biochemistry and Molecular Biology
Issue number1
StatePublished - Jan 2000


  • CYP6B8
  • Cytochrome P450
  • Furanocoumarins
  • Helicoverpa zea
  • Monooxygenase
  • Xanthotoxin
  • α- cypermethrin

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Insect Science


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