Metabolic activation of aromatic and heterocyclic N-hydroxyarylamines by wild-type and mutant recombinant human NAT1 and NAT2 acetyltransferases.
Recombinant human NAT1 and polymorphic NAT2 wild-type and mutant N-acetyltransferases (encoded by NAT2 alleles with mutations at 282/857, 191, 282/590, 341/803, 341/481/803, and 341/481) were expressed in Escherichia coli strains XA90 and/or JM105, and tested for their capacity to catalyze the metabolic activation (via O-acetylation) of the N-hydroxy (N-OH) derivatives of 2-aminofluorene (AF), and the heterocyclic arylamine mutagens 2-amino-3-methylimidazo [4,5-f]quinoline (IQ), 2-amino-3,4-dimethyl-imidazo[4,5-f]quinoxaline (MeIQx), and 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP). Both NAT1 and NAT2 (including all mutant human NAT2s tested) catalyzed the metabolic activation of each of the N-hydroxyarylamines to products that bound to DNA. Metabolic activation of N-OH-AF was greater than that of the heterocyclic N-hydroxyarylamines. The relative capacity of NAT1 versus NAT2 to catalyze activation varied with N-hydroxyarylamine substrate. N-OH-MeIQx and N-OH-PhIP exhibited a relative specificity for NAT2. These results provide mechanistic support for a role of the genetic acetylation polymorphism in the metabolic activation of heterocyclic amine mutagens and carcinogens.
Hein
D W
DW
Department of Pharmacology and Toxicology, University of North Dakota School of Medicine, Grand Forks 58202-9037.
Rustan
T D
TD
Ferguson
R J
RJ
Doll
M A
MA
Gray
K
K
D000107:Acetylation; D000123:Acetyltransferases / Q000378:metabolism*; D000217:Acyltransferases / Q000378:metabolism; D000588:Amines / Q000378:metabolism; D001191:Arylamine N-Acetyltransferase / Q000378:metabolism*; D001483:Base Sequence; D001711:Biotransformation; D015153:Blotting, Western; D006571:Heterocyclic Compounds / Q000378:metabolism; D006801:Humans; D006898:Hydroxylamines / Q000378:metabolism* / Q000493:pharmacokinetics; D008969:Molecular Sequence Data; D011110:Polymorphism, Genetic; D011994:Recombinant Proteins / Q000378:metabolism; D013379:Substrate Specificity
D000588:Amines; D006571:Heterocyclic Compounds; D006898:Hydroxylamines; D011994:Recombinant Proteins; D000217:Acyltransferases; D000123:Acetyltransferases; C061313:protein N-terminal acetyltransferase; C019736:N-hydroxyarylamine O-acetyltransferase; D001191:Arylamine N-Acetyltransferase; C478900:NAT2 protein, human