Abstract

Purification, cloning, and three-dimensional structure prediction of Micrococcus luteus FAD-containing tyramine oxidase. Biochem. Biophys. Res. Commun. 268: 293-297. 2000. J.H. Roh, J. Wouters, E. Depiereux, H. Yukawa, M. Inui, H. Minami, H. Suzuki and H. Kumagai.

The FAD-containing tyramine oxidase enzyme and gene from the Gram (+) bacterium Micrococcus luteus were isolated, and computer prediction was used to propose a preliminary 3D model of the protein. A 2.8-kb Sau3AI fragment containing the structural gene of tyramine oxidase was cloned from a M. luteus genomic DNA library. The 1332 bp gene encodes a protein of 443 amino acids, with a calculated molecular mass of 49.1 kDa. The enzyme was found to be a homodimer with a molecular weight of 49,000. It oxidizes tyramine, adrenaline, 3-hydroxytyramine, dopamine, and noradrenaline, and was reversibly inhibited by FAD-containing monoamine oxidase A and B specific inhibitors. Sequence comparison show that tyramine oxidase is smaller than other FAD-amine oxidases but that it contains well-conserved amino acid residues reported in all other FAD-amine oxidases. A hypothetical three-dimensional structure of tyramine oxidase has also been proposed based on secondary structure predictions, threading, and comparative modeling. Copyright 2000 Academic Press.

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