Subject(s)
Aspartic Acid Endopeptidases/chemistry , Aspartic Acid Endopeptidases/genetics , Metalloendopeptidases/chemistry , Metalloendopeptidases/genetics , Methyltransferases/chemistry , S-Adenosylmethionine/metabolism , Aspartic Acid Endopeptidases/metabolism , Crystallography, X-Ray , Endothelin-Converting Enzymes , Humans , Metalloendopeptidases/metabolism , Methyltransferases/genetics , Models, Molecular , Protein Conformation , Protein Folding , S-Adenosylmethionine/chemistryABSTRACT
The human arylamine N-acetyltransferases NAT1 and NAT2 play an important role in the biotransformation of a plethora of aromatic amine and hydrazine drugs. They are also able to participate in the bioactivation of several known carcinogens. Each of these enzymes is genetically variable in human populations, and polymorphisms in NAT genes have been associated with various cancers. Here we have solved the high resolution crystal structures of human NAT1 and NAT2, including NAT1 in complex with the irreversible inhibitor 2-bromoacetanilide, a NAT1 active site mutant, and NAT2 in complex with CoA, and have refined them to 1.7-, 1.8-, and 1.9-A resolution, respectively. The crystal structures reveal novel structural features unique to human NATs and provide insights into the structural basis of the substrate specificity and genetic polymorphism of these enzymes.
Subject(s)
Arylamine N-Acetyltransferase/chemistry , Isoenzymes/chemistry , Acetanilides/chemistry , Amino Acid Sequence , Binding Sites , Crystallography, X-Ray/methods , Humans , Molecular Conformation , Molecular Sequence Data , Mutation , Polymorphism, Genetic , Protein Binding , Sequence Homology, Amino Acid , Substrate SpecificityABSTRACT
MOTIVATION: In the present work we combine computational analysis and experimental data to explore the extent to which binding site similarities between members of the human cytosolic sulfotransferase family correlate with small-molecule binding profiles. Conversely, from a small-molecule point of view, we explore the extent to which structural similarities between small molecules correlate to protein binding profiles. RESULTS: The comparison of binding site structural similarities and small-molecule binding profiles shows that proteins with similar small-molecule binding profiles tend to have a higher degree of binding site similarity but the latter is not sufficient to predict small-molecule binding patterns, highlighting the difficulty of predicting small-molecule binding patterns from sequence or structure. Likewise, from a small-molecule perspective, small molecules with similar protein binding profiles tend to be topologically similar but topological similarity is not sufficient to predict their protein binding patterns. These observations have important consequences for function prediction and drug design.
