2oy0: Difference between revisions

[[Image:2oy0.gif|left|200px]]<br /><applet load="2oy0" size="350" color="white" frame="true" align="right" spinBox="true"  

The plus-strand RNA genome of flavivirus contains a 5' terminal cap 1 structure (m7GpppAmG). The flaviviruses encode one methyltransferase, located at the N-terminal portion of the NS5 protein, to catalyze both guanine N-7 and ribose 2'-OH methylations during viral cap formation. Representative flavivirus methyltransferases from dengue, yellow fever, and West Nile virus (WNV) sequentially generate GpppA--&gt;m7GpppA--&gt;m7GpppAm. The 2'-O methylation can be uncoupled from the N-7 methylation, since m7GpppA-RNA can be readily methylated to m7GpppAm-RNA. Despite exhibiting two distinct methylation activities, the crystal structure of WNV methyltransferase at 2.8 A resolution showed a single binding site for S-adenosyl-L-methionine (SAM), the methyl donor. Therefore, substrate GpppA-RNA should be repositioned to accept the N-7 and 2'-O methyl groups from SAM during the sequential reactions. Electrostatic analysis of the WNV methyltransferase structure showed that, adjacent to the SAM-binding pocket, is a highly positively charged surface that could serve as an RNA binding site during cap methylations. Biochemical and mutagenesis analyses show that the N-7 and 2'-O cap methylations require distinct buffer conditions and different side chains within the K61-D146-K182-E218 motif, suggesting that the two reactions use different mechanisms. In the context of complete virus, defects in both methylations are lethal to WNV; however, viruses defective solely in 2'-O methylation are attenuated and can protect mice from later wild-type WNV challenge. The results demonstrate that the N-7 methylation activity is essential for the WNV life cycle and, thus, methyltransferase represents a novel target for flavivirus therapy.

2OY0 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/West_nile_virus West nile virus] with <scene name='pdbligand=SAH:'>SAH</scene> as [http://en.wikipedia.org/wiki/ligand ligand]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2OY0 OCA].  

Structure and function of flavivirus NS5 methyltransferase., Zhou Y, Ray D, Zhao Y, Dong H, Ren S, Li Z, Guo Y, Bernard KA, Shi PY, Li H, J Virol. 2007 Apr;81(8):3891-903. Epub 2007 Jan 31. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=17267492 17267492]

[[Category: Li, H M.]]

[[Category: Shi,P Y.]]

[[Category: Zhao, Y W.]]

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