Two O-methyltransferases from Picea abies: characterization and molecular basis of different reactivity.
O-Methyltransferase (OMT) catalyzes the transfer of a methyl group from S-adenosyl methionine (SAM) to hydroxyl groups of methyl acceptors. Two OMTs, PaOMT2 and PaOMT3, from Picea abies showed 93.5% identity at the amino acid level. However, PaOMT3 catalyzed the reaction more efficiently than PaOMT2 with several phenolic compounds, including quercetin and caffeoyl-CoA. To determine the critical amino acids for the different reactivity of the two OMTs, site-directed mutagenesis was carried out. The amino acid proline at position 35 in PaOMT2 and leucine in PaOMT3 is a critical amino acid for their reactivity. Molecular modeling showed that the sequential change triggered by Leu35 resulted in a change in the size of the substrate binding pocket, which could account for the different catalytic reactivity of two OMTs.
Kim
Bong-Gyu
BG
Department of Bioscience and Biotechnology, Bio/Molecular Informatics Center, Konkuk University, Seoul, Korea.
Kim
Dae Hwan
DH
Sung
Su Hyun
SH
Kim
Dong-Eun
DE
Chong
Youhoon
Y
Ahn
Joong-Hoon
JH
D000595:Amino Acid Sequence; D002851:Chromatography, High Pressure Liquid; D008780:Methyltransferases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D028222:Picea / Q000201:enzymology* / Q000235:genetics; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D017433:Protein Structure, Secondary; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid
D010940:Plant Proteins; D008780:Methyltransferases