Structural and Functional Characterization of CalS11, a TDP-Rhamnose 3鈥?O-Methyltransferase Involved in Calicheamicin Biosynthesis

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• 作者：Shanteri Singh ; Aram Chang ; Kate E. Helmich ; Craig A. Bingman ; Russell L. Wrobel ; Emily T. Beebe ; Shin-ichi Makino ; David J. Aceti ; Kevin Dyer ; Greg L. Hura ; Manjula Sunkara ; Andrew J. Morris ; George N. Phillips ; Jr. ; Jon S. Thorson
• 刊名：ACS Chemical Biology
• 出版年：2013
• 出版时间：July 19, 2013
• 年：2013
• 卷：8
• 期：7
• 页码：1632-1639
• 全文大小：422K
• 年卷期：v.8,no.7(July 19, 2013)
• ISSN：1554-8937

文摘

Sugar methyltransferases (MTs) are an important class of tailoring enzymes that catalyze the transfer of a methyl group from S-adenosyl-l-methionine to sugar-based N-, C- and O-nucleophiles. While sugar N- and C-MTs involved in natural product biosynthesis have been found to act on sugar nucleotide substrates prior to a subsequent glycosyltransferase reaction, corresponding sugar O-methylation reactions studied thus far occur after the glycosyltransfer reaction. Herein we report the first in vitro characterization using ¹H鈥?sup>13C-gHSQC with isotopically labeled substrates and the X-ray structure determination at 1.55 脜 resolution of the TDP-3鈥?O-rhamnose-methyltransferase CalS11 from Micromonospora echinospora. This study highlights a unique NMR-based methyltransferase assay, implicates CalS11 to be a metal- and general acid/base-dependent O-methyltransferase, and as a first crystal structure for a TDP-hexose-O-methyltransferase, presents a new template for mechanistic studies and/or engineering.