Structural and functional divergence of insect CYP6B proteins: From specialist to generalist cytochrome P450

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

Research output: Contribution to journalArticlepeer-review

248 Scopus citations


How polyphagous herbivores cope with the diversity and unpredictability of plant defenses remains largely unknown at both the genetic and molecular levels. To examine whether generalist counterdefense enzymes are structurally more flexible and functionally more diverse, two counterdefensive allelochemical-metabolizing cytochrome P450 proteins, CYP6B1 from the specialist Papilio polyxenes, feeding on furanocoumarin-containing plants, and CYP6B8 from the generalist Helicoverpa zea, feeding on hundreds of host plant species, are compared structurally and functionally. Molecular modeling indicates that CYP6B8 has more flexible overall folding, a more elastic catalytic pocket, and one more substrate access channel than CYP6B1. Baculovirus-mediated expression of the CYP6B8 and CYP6B1 proteins demonstrates that CYP6B8 metabolizes six biosynthetically diverse plant allelochemicals (xanthotoxin, quercetin, flavone, chlorogenic acid, indole-3-carbinol, and rutin) and three insecticides (diazinon, cypermethrin, and aldrin), whereas CYP6B1 metabolizes only two allelochemicals (xanthotoxin and flavone) and one insecticide (diazinon) of those tested. These results indicate that generalist counterdefense proteins are capable of accepting a more structurally diverse array of compounds compared with specialist counterdefense proteins.

Original languageEnglish (US)
Pages (from-to)2939-2944
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number9
StatePublished - Mar 2 2004

ASJC Scopus subject areas

  • General


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