Transcriptional response elements in the promoter of CYP6B1, an insect P450 gene regulated by plant chemicals

Rebecca A. Petersen, Hataichanoke Niamsup, May R. Berenbaum, Mary A. Schuler

Research output: Contribution to journalArticle

Abstract

Papilio polyxenes, a lepidopteran continually exposed to toxic furanocoumarins in its hostplants, owes its tolerance to these compounds to the transcriptional induction of the CYP6B1 gene encoding a P450 capable of metabolizing linear furanocoumarins, such as xanthotoxin, at high rates. Transient expression of various lengths of wild-type and mutant CYP6B1v3 promoter in lepidopteran Sf9 cells defines a positive element (XRE-xan) from -136 to -119 required for both basal and xanthotoxin-inducible transcription and a negative element from -228 to -146 that represses basal transcription. Fusion of the CYP6B1v3 XRE-xan element to the Drosophila melanogaster Eip28/29 core promoter indicates that the XRE-xan functions in conjunction with its own core promoter but not with a heterologous core promoter. Sequence searches of the CYP6B1v3 proximal promoter region revealed a number of putative elements (XRE-AhR, ARE, OCT-1, EcRE, C/EBP, Inr) sharing sequence similarity with those in other regulated vertebrate and insect promoters. Mutation of TGAC nucleotides shared by the overlapping EcRE/ARE/XRE-xan indicates that this sequence is essential for basal and regulated transcription of this gene. Mutagenesis in the non-overlapping region of the EcRE indicates it modulates basal transcription. These findings are incorporated into a working model for regulation of this toxin-inducible promoter.

Original languageEnglish (US)
Pages (from-to)269-282
Number of pages14
JournalBiochimica et Biophysica Acta - General Subjects
Volume1619
Issue number3
DOIs
StatePublished - Feb 17 2003

Keywords

  • Cytochrome P450 monooxygenase
  • Furanocoumarin
  • Papilio polyxenes
  • XRE-xan

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Molecular Biology

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