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Guanosine N7 methyl-transferase sub-complex (D1-D12) of the vaccinia virus mRNA capping enzymeGuanosine N7 methyl-transferase sub-complex (D1-D12) of the vaccinia virus mRNA capping enzyme
Structural highlights
FunctionMCEL_VACCW Catalytic subunit of the mRNA capping enzyme which catalyzes three enzymatic reactions: the 5' triphosphate end of the pre-mRNA is hydrolyzed to a diphosphate by RNA 5' triphosphatase; the diphosphate RNA end is capped with GMP by RNA guanylyltransferase and the GpppN cap is methylated by RNA (guanine-N7) methyltransferase. Heterodimeric mRNA capping enzyme catalyzes the linkage of a N7-methyl-guanosine moiety to the first transcribed nucleotide (cap 0 structure), whereas the polymerase associated VP39 is responsible for a second methylation at the 2'-O position of the ribose (cap 1 structure).[1] [2] [3] The heterodimeric enzyme is also involved in early viral gene transcription termination and intermediate viral gene transcription initiation. Early gene transcription termination requires the termination factor VTF, the DNA-dependent ATPase NPH-I and the Rap94 subunit of the viral RNA polymerase, as well as the presence of a specific termination motif. Binds, together with RAP94, to the termination motif 5'-UUUUUNU-3' in the nascent early mRNA.[4] [5] [6] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedThe vaccinia virus mRNA capping enzyme is a multifunctional heterodimeric protein associated with the viral polymerase that both catalyses the three steps of mRNA capping and regulates gene transcription. The structure of a subcomplex comprising the C-terminal N7-methyl-transferase (MT) domain of the large D1 subunit, the stimulatory D12 subunit and bound S-adenosyl-homocysteine (AdoHcy) has been determined at 2.7 A resolution and reveals several novel features of the poxvirus capping enzyme. The structure shows for the first time the critical role played by the proteolytically sensitive N-terminus of the MT domain in binding the methyl donor and in catalysis. In addition, the poxvirus enzyme has a completely unique mode of binding of the adenosine moiety of AdoHcy, a feature that could be exploited for design of specific anti-poxviral compounds. The structure of the poxvirus-specific D12 subunit suggests that it was originally an RNA cap 2'O-MT that has evolved to a catalytically inactive form that has been retained for D1 stabilisation and MT activity enhancement through an allosteric mechanism. Structural insights into the mechanism and evolution of the vaccinia virus mRNA cap N7 methyl-transferase.,De la Pena M, Kyrieleis OJ, Cusack S EMBO J. 2007 Nov 28;26(23):4913-25. Epub 2007 Nov 8. PMID:17989694[7] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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