Publication Abstract from PubMed
A suite of crystal structures is reported for a cellular mRNA cap (guanine-N7) methyltransferase in complex with AdoMet, AdoHcy, and the cap guanylate. Superposition of ligand complexes suggests an in-line mechanism of methyl transfer, albeit without direct contacts between the enzyme and either the N7 atom of guanine (the attacking nucleophile), the methyl carbon of AdoMet, or the sulfur of AdoMet/AdoHcy (the leaving group). The structures indicate that catalysis of cap N7 methylation is accomplished by optimizing proximity and orientation of the substrates, assisted by a favorable electrostatic environment. The enzyme-ligand structures, together with new mutational data, fully account for the biochemical specificity of the cap guanine-N7 methylation reaction, an essential and defining step of eukaryotic mRNA synthesis.
Structure and mechanism of mRNA cap (guanine-N7) methyltransferase.,Fabrega C, Hausmann S, Shen V, Shuman S, Lima CD Mol Cell. 2004 Jan 16;13(1):77-89. PMID:14731396[1]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
