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

Abstract

Catechol‐O‐methyltransferase (COMT1) 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. spCOMT 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 spCOMT was purified and kinetically characterized for the first time. The enzymology assays indicate that spCOMT is a metal‐dependent enzyme and belongs to class I OMTs. In addition, the crystal structures of apo‐spCOMT and SAM‐complexed spCOMT were also presented, revealing that spCOMT possesses a conserved SAM‐binding site and Mg2+ pocket, but a distinct substrate pocket was not present in homologs. The mutagenesis ITC analysis revealed the SAM recognition characteristics of spCOMT. Based on all of the above findings, we speculated about the putative substrates’ characteristics and the substrate recognition mechanisms of spCOMT. This work will help in elucidating the physiological functions of spCOMT in S. pombe. © 2018 IUBMB Life, 71(3):330–339, 2019

Structural and biochemical characterization of Rv0187, an O-methyltransferase from Mycobacterium tuberculosis

“…However, this hypothesis is likely to be ruled out for Rv0187, since dissociation constants for SAM in the presence ( K d = 12.5 μM) or absence of metal ions ( K d = 9.3 μM) do not change significantly indicating that affinity for SAM is independent of the active-site metal ion. Other known class I COMTs exhibit similar K d values for SAM, e.g ., 8.6 μM for SbCCoAMT from S. bicolor and 13.6 μM for spCOMT from Schizosaccharomyces pombe 15,32 .…”