Functional and structural characterization of a novel catechol-O-methyltransferase from Schizosaccharomyces pombe

Catechol- O -methyltransferase (COMT 1 ) catalyzes the transfer of a methyl group from S-adenosylmethionine (SAM) to various catechol substrates. COMTs play vital roles in physiological processes in animals, plants, and fungi, as well as bacteria, and have essential application values in industry. sp COMT is a probable COMT from Schizosaccharomyces pombe . It has an extraordinary intracellular distribution different from other homologs and would thus be predicted to perform a distinct physiological function. In this report, recombinant sp COMT was purified and kinetically characterized for the first time. The enzymology assays indicate that sp COMT is a metal-dependent enzyme and belongs to class I OMTs. In addition, the crystal structures of apo- sp COMT and SAM-complexed sp COMT were also presented, revealing that sp COMT possesses a conserved SAM-binding site and Mg 2+ pocket, but a distinct substrate pocket was not present in homologs. The mutagenesis ITC analysis revealed the SAM recognition characteristics of sp COMT. Based on all of the above findings, we speculated about the putative substrates’ characteristics and the substrate recognition mechanisms of sp COMT. This work will help in elucidating the physiological functions of sp COMT in S. pombe . © 2018 IUBMB Life, 71(3):330–339, 2019