1RI3

Structure and mechanism of mRNA cap (guanine N-7) methyltransferase

Summary for 1RI3

• Entry DOI: 10.2210/pdb1ri3/pdb
• Related: 1RI1 1RI2 1RI4 1RI5
• Descriptor: mRNA CAPPING ENZYME, S-ADENOSYL-L-HOMOCYSTEINE (3 entities in total)
• Functional Keywords: methyltransferase, rna, cap, m7g, messenger rna cap, transferase
• Biological source: Encephalitozoon cuniculi
• Cellular location: Nucleus (By similarity): Q8SR66
• Total number of polymer chains: 1
• Total formula weight: 35208.10

Authors

Fabrega, C.,Hausmann, S.,Shen, V.,Shuman, S.,Lima, C.D. (deposition date: 2003-11-16, release date: 2004-02-03, Last modification date: 2024-02-14)

Primary citation

Fabrega, C.,Hausmann, S.,Shen, V.,Shuman, S.,Lima, C.D.
Structure and mechanism of mRNA cap (Guanine-n7) methyltransferase
Mol.Cell, 13:77-89, 2004

PubMed Abstract: 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.

PubMed: 14731396
DOI: 10.1016/S1097-2765(03)00522-7

Experimental method

X-RAY DIFFRACTION (2.5 Å)