Genetic polymorphisms of the human CYP2A13 gene: identification of single-nucleotide polymorphisms and functional characterization of an Arg257Cys variant
Autor: | Xinxin Ding, Hongming Li, Xiuling Zhang, Ting Su, Michele Caggana, Qing Yu Zhang, Jun Gu |
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Rok vydání: | 2002 |
Předmět: |
Single-nucleotide polymorphism
Biology Arginine Polymerase Chain Reaction Polymorphism Single Nucleotide law.invention Exon Cytochrome P-450 Enzyme System law Genetic variation Coding region Humans Cysteine Allele Gene Polymerase chain reaction Polymorphism Single-Stranded Conformational DNA Primers Pharmacology Genetics Racial Groups Genetic Variation Molecular biology United States Kinetics CYP2A13 Amino Acid Substitution Molecular Medicine Aryl Hydrocarbon Hydroxylases |
Zdroj: | The Journal of pharmacology and experimental therapeutics. 302(2) |
ISSN: | 0022-3565 |
Popis: | Human cytochrome P450 2A13 (CYP2A13), which is highly efficient in the metabolic activation of a major tobacco-specific carcinogen, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), may play important roles in xenobiotic toxicity and tobacco-related tumorigenesis in the respiratory tract. The aim of this study was to identify any genetic polymorphisms of the CYP2A13 gene, which may alter the metabolic capacities of the enzyme. Polymerase chain reaction (PCR) single-strand conformational polymorphism analysis was used to identify single-nucleotide polymorphisms (SNPs) in all of the exons and at the exon-intron boundaries, and PCR-restriction fragment length polymorphism analysis and DNA sequencing were used to determine the frequencies of the newly identified variant alleles in the four major ethnic groups. Blood spot DNA from more than 100 individuals was used for these analyses. Seven variant alleles were found, but only one SNP was detected in the coding region, in exon 5, leading to an Arg257Cys amino acid change. The frequencies of the Arg257Cys allele in white, black, Hispanic, and Asian individuals are 1.9%, 14.4%, 5.8%, and 7.7%, respectively. Functional analysis of the variant protein was performed following its heterologous expression. The Arg257Cys variant was 37 to 56% less active than the wild-type Arg-257 protein toward all substrates tested. With NNK, Cys-257 had higher K m and lower V max values than did Arg-257, with a >2-fold decrease in catalytic efficiency. The Arg257Cys mutation could provide some protection against xenobiotic toxicity in the respiratory tract to individuals who are homozygous for the Cys-257 allele. |
Databáze: | OpenAIRE |
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