Substrate-specific modulation of CYP3A4 activity by genetic variants of cytochrome P450 oxidoreductase

Vishal Agrawal, Ji Ha Choi, Kathleen M. Giacomini, Walter L. Miller

Research output: Contribution to journalArticlepeer-review

93 Scopus citations

Abstract

OBJECTIVES: CYP3A4 receives electrons from P450 oxidoreductase (POR) to metabolize about 50% of clinically used drugs. There is substantial inter-individual variation in CYP3A4 catalytic activity that is not explained by CYP3A4 genetic variants. CYP3A4 is flexible and distensible, permitting it to accommodate substrates varying in shape and size. To elucidate the mechanisms of variability in CYP3A4 catalysis, we examined the effects of genetic variants of POR, and explored the possibility that substrate-induced conformational changes in CYP3A4 differentially affect the ability of POR variants to support catalysis. METHODS: We expressed human CYP3A4 and four POR variants (Q153R, A287P, R457H, A503V) in bacteria, reconstituted them in vitro and measured the Michaelis constant and maximum velocity with testosterone, midazolam, quinidine and erythromycin as substrates. RESULTS: POR A287P and R457H had low activity with all substrates; Q153R had 76-94% of wild-type (WT) activity with midazolam and erythromycin, but 129-150% activity with testosterone and quinidine. The A503V polymorphism reduced the CYP3A4 activity to 61-77% of WT with testosterone and midazolam, but had nearly WT activity with quinidine and erythromycin. CONCLUSION: POR variants affect CYP3A4 activities. The impact of a POR variant on catalysis by CYP3A4 is substrate-specific, probably because of substrate-induced conformational changes in CYP3A4.

Original languageEnglish
Pages (from-to)611-618
Number of pages8
JournalPharmacogenetics and Genomics
Volume20
Issue number10
DOIs
StatePublished - Oct 2010

Keywords

  • cytochrome P450
  • drug metabolism
  • electron transfer
  • enzymology
  • pharmacogenetics
  • proteinprotein interaction

Fingerprint

Dive into the research topics of 'Substrate-specific modulation of CYP3A4 activity by genetic variants of cytochrome P450 oxidoreductase'. Together they form a unique fingerprint.

Cite this