3bus

Publication Abstract from PubMed

The 2.65-angstroms crystal structure of the rebeccamycin 4'-O-methyltransferase RebM in complex with S-adenosyl-l-homocysteine revealed RebM to adopt a typical S-adenosylmethionine-binding fold of small molecule O-methyltransferases (O-MTases) and display a weak dimerization domain unique to MTases. Using this structure as a basis, the RebM substrate binding model implicated a predominance of nonspecific hydrophobic interactions consistent with the reported ability of RebM to methylate a wide range of indolocarbazole surrogates. This model also illuminated the three putative RebM catalytic residues (His140/141 and Asp166) subsequently found to be highly conserved among sequence-related natural product O-MTases from GC-rich bacteria. Interrogation of these residues via site-directed mutagenesis in RebM demonstrated His140 and Asp166 to be most important for catalysis. This study reveals RebM to be a member of the general acid/base-dependent O-MTases and, as the first crystal structure for a sugar O-MTase, may also present a template toward the future engineering of natural product MTases for combinatorial applications.

Structure and mechanism of the rebeccamycin sugar 4'-O-methyltransferase RebM.,Singh S, McCoy JG, Zhang C, Bingman CA, Phillips GN Jr, Thorson JS J Biol Chem. 2008 Aug 15;283(33):22628-36. Epub 2008 May 23. PMID:18502766^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.