Faculty Collaboration Database

Genotyping and site-directed mutagenesis of a cytochrome P450 meander Pro-X-Arg motif critical to CYP4B1 catalysis. Toxicol Appl Pharmacol 2003 Jan 15;186(2):119-26

Date

03/18/2003

Pubmed ID

12639503

DOI

10.1016/s0041-008x(02)00028-5

Scopus ID

2-s2.0-0037438020 (requires institutional sign-in at Scopus site)   24 Citations

Abstract

CYP4B1 isoforms from rodents and other common laboratory animals are involved in the bioactivation of a range of protoxins, including 2-aminofluorene, 4-ipomeanol, and valproic acid. However, an earlier study provided evidence for a human allele encoding a nonfunctional CYP4B1 enzyme due to a Pro427Ser transversion in the meander region of the protein. In the present study, the CYP4B1 gene from several racial groups, Caucasians, African-Americans, and Hispanics, and from six nonhuman primate species was genotyped using a PCR-Hinf1 restriction enzyme fragment length polymorphism assay or by direct sequencing. All human populations examined were found to possess only the Ser allele at codon 427 ((1279)TCT) and all of the nonhuman primate species possessed only the Pro (CCT) allele. Therefore, an inactivating (1279)C-->T mutation in the human CYP4B1 gene likely arose following divergence of the Homo and Pan clades. Amino acid sequence alignments revealed further that this key Pro residue is located two amino acid residues N-terminal to the distal Arg of a Glu-Arg-Arg triad thought to participate in heme binding and/or redox partner interactions. Mutation of the corresponding Arg424 residue in rabbit CYP4B1 to Leu, but not His, resulted in a loss of lauric acid hydroxylase activity and ability to generate a reduced-CO binding spectrum. These data provide additional evidence for the importance of this meander region Pro-X-Arg motif in CYP4B1 heme binding and catalytic function.

Author List

Zheng YM, Henne KR, Charmley P, Kim RB, McCarver DG, Cabacungan ET, Hines RN, Rettie AE

Author

Erwin Cabacungan MD Associate Professor in the Pediatrics department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

Amino Acid Motifs
Amino Acid Sequence
Animals
Aryl Hydrocarbon Hydroxylases
Catalysis
Cytochrome P-450 CYP4A
Cytochrome P-450 Enzyme System
Genotype
Humans
Mixed Function Oxygenases
Molecular Sequence Data
Mutagenesis, Site-Directed
Primates
Rabbits
Structure-Activity Relationship