Biomaterial Database

Characterization of a highly conserved FAD-binding site in human monoamine oxidase B. 1998

B P Zhou, and B Wu, and S W Kwan, and C W Abell

Division of Medicinal Chemistry, College of Pharmacy, and the Institute for Neuroscience and the Institute for Cellular and Molecular Biology, University of Texas, Austin, Texas 78712-1074, USA.

Monoamine oxidase B (MAO B) catalyzes the oxidative deamination of biogenic and xenobiotic amines. The oxidative step is coupled to the reduction of an obligatory cofactor, FAD, which is covalently linked to the apoenzyme at Cys397. Our previous studies identified two noncovalent flavin-binding regions in MAO B (residues 6-34 and 39-46) (Kwan, S.-W., Lewis, D. A., Zhou, B. P., and Abell, C. W. (1995) Arch. Biochem. Biophys. 316, 385-391; Zhou, B. P., Lewis, D. A., Kwan, S.-W., Kirksey, T. J., and Abell, C. W. (1995) Biochemistry 34, 9526-9531). In these regions, Glu34 and Tyr44 were found to be required for the initial binding of FAD. By comparing sequences with enzymes in the oxidoreductase family, we now have found an additional FAD-binding site in MAO B (residues 222-227), which is highly conserved across species (human, bovine, and rat). This conserved sequence contains adjacent glycine and aspartate residues (Gly226 and Asp227). Based on the x-ray crystal structures of several oxidoreductases (Eggink, G., Engel, H., Vriend, G., Terpstra, P., and Witholt, B. (1990) J. Mol. Biol. 212, 135-142; Van Driessche, G., Kol, M., Chen, Z.-W., Mathews, F. S., Meyer, T. E., Bartsch, R. G., Cusanovich, M. A., and Van Beeumen, J. J. (1996) Protein Sci. 5, 1753-1764), the Gly residue at the end of a beta-strand facilitates a sharp turn and extends the beta-carbonyl group of Asp to interact with the 3'-hydroxyl group of the ribityl chain of FAD. To assess the hypothesis that Gly226 and Asp227 are involved in FAD binding in MAO B, site-specific mutants that encode substitutions at these positions were prepared and expressed in mammalian COS-7 cells. Our results indicate that Gly226 and the beta-carbonyl group of Asp227 are required for covalent flavinylation and catalytic activity of MAO B, but not for noncovalent binding of FAD. Our studies also reveal that mutagenesis at Glu34 and Tyr44 not only interferes with covalent flavinylation and catalytic activity of MAO B, but also with noncovalent binding of FAD. Based on these collective results, we propose that the coupling of FAD to the MAO B apoenzyme is a multistep process.

UI	MeSH Term	Description	Entries
D008969	Molecular Sequence Data	Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.	Sequence Data, Molecular,Molecular Sequencing Data,Data, Molecular Sequence,Data, Molecular Sequencing,Sequencing Data, Molecular
D008995	Monoamine Oxidase	An enzyme that catalyzes the oxidative deamination of naturally occurring monoamines. It is a flavin-containing enzyme that is localized in mitochondrial membranes, whether in nerve terminals, the liver, or other organs. Monoamine oxidase is important in regulating the metabolic degradation of catecholamines and serotonin in neural or target tissues. Hepatic monoamine oxidase has a crucial defensive role in inactivating circulating monoamines or those, such as tyramine, that originate in the gut and are absorbed into the portal circulation. (From Goodman and Gilman's, The Pharmacological Basis of Therapeutics, 8th ed, p415) EC 1.4.3.4.	Amine Oxidase (Flavin-Containing),MAO,MAO-A,MAO-B,Monoamine Oxidase A,Monoamine Oxidase B,Type A Monoamine Oxidase,Type B Monoamine Oxidase,Tyramine Oxidase,MAO A,MAO B,Oxidase, Monoamine,Oxidase, Tyramine
D011485	Protein Binding	The process in which substances, either endogenous or exogenous, bind to proteins, peptides, enzymes, protein precursors, or allied compounds. Specific protein-binding measures are often used as assays in diagnostic assessments.	Plasma Protein Binding Capacity,Binding, Protein
D002384	Catalysis	The facilitation of a chemical reaction by material (catalyst) that is not consumed by the reaction.	Catalyses
D005182	Flavin-Adenine Dinucleotide	A condensation product of riboflavin and adenosine diphosphate. The coenzyme of various aerobic dehydrogenases, e.g., D-amino acid oxidase and L-amino acid oxidase. (Lehninger, Principles of Biochemistry, 1982, p972)	FAD,Flavitan,Dinucleotide, Flavin-Adenine,Flavin Adenine Dinucleotide
D005420	Flavoproteins		Flavoprotein
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000595	Amino Acid Sequence	The order of amino acids as they occur in a polypeptide chain. This is referred to as the primary structure of proteins. It is of fundamental importance in determining PROTEIN CONFORMATION.	Protein Structure, Primary,Amino Acid Sequences,Sequence, Amino Acid,Sequences, Amino Acid,Primary Protein Structure,Primary Protein Structures,Protein Structures, Primary,Structure, Primary Protein,Structures, Primary Protein
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D001483	Base Sequence	The sequence of PURINES and PYRIMIDINES in nucleic acids and polynucleotides. It is also called nucleotide sequence.	DNA Sequence,Nucleotide Sequence,RNA Sequence,DNA Sequences,Base Sequences,Nucleotide Sequences,RNA Sequences,Sequence, Base,Sequence, DNA,Sequence, Nucleotide,Sequence, RNA,Sequences, Base,Sequences, DNA,Sequences, Nucleotide,Sequences, RNA