Sandbox Reserved 428: Difference between revisions
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structure shows semblance to other members of the Flavivirus family as can be seen when comparing it to <scene name='48/483885/Wnv_mtase/3'>WNV MTase (West Nile Virus Methyltransferase)</scene>, and <scene name='48/483885/Denv-2_mtase/2'>DENV-2 MTase</scene>. Structural similarity especially appears within the binding pocket of these MTases regardless of SAH/SAM ligands and therefore the methylated-state of the SAM molecule shows unimportant affect over ligand-protein reciprocity. | structure shows semblance to other members of the Flavivirus family as can be seen when comparing it to <scene name='48/483885/Wnv_mtase/3'>WNV MTase (West Nile Virus Methyltransferase)</scene>, and <scene name='48/483885/Denv-2_mtase/2'>DENV-2 MTase</scene>. Structural similarity especially appears within the binding pocket of these MTases regardless of SAH/SAM ligands and therefore the methylated-state of the SAM molecule shows unimportant affect over ligand-protein reciprocity. | ||
A unique hydrophobic pocket (viewable in <scene name='48/483885/Hydrophobic_pocket_denv-3mtase/3'caption | A unique hydrophobic pocket (viewable in <scene name='48/483885/Hydrophobic_pocket_denv-3mtase/3' caption='3p8z, hydrophobic pocket above adenine base of SAH inhbitor'>DENV-3 MTase Hydrophobic Surface Model</scene> and <scene name='48/483885/Hydrophobic_pocket_denv-2mtase/2'>DENV-2 MTase Hydrophobic Surface Model</scene>) was identified in this protein above the adenine base (of SAH) and was first identified in West Nile Virus Methyltransferase. It can be found within conserved amino acids Phe-133, Ile-147, Gly-148, Glu-149, Arg-160, Arg 163, Val-164, and Leu-182. Phe-133 and Ile-147 are of particular interest because of their functionality in the binding cavity and their formation of the hydrophobic pocket. Alanine mutations revealed various effects on the production and viral titer of DENV-3 MTase. The Table below<ref>J Biol Chem. 2011 Feb 25;286(8):6233-40. Epub 2010 Dec 8. PMID:21147775 doi:10.1074/jbc.M110.179184</ref>, shows the various effects of Alanine mutations at selected sites. These transfectation experiments revealed that mutations at the N-7 (R160A, R160A) or 2’-O (F133A, L18A) methylation activities were significantly depreciated. Melting temperatures in the table indicate low mis-folding in the mutant MTases with respect to the wild type. These attributes confirm observations in WNV MTase; that the identified hydrophobic pocket is critical to Flavivirus cap methylations and replication within cell environments. Diminishment in these properties decrease the virus’s overall potency. Therefore selective inhibition of DENV-3 MTase at this unique binding cavity becomes a viable antiviral strategy.<ref>J Biol Chem. 2011 Feb 25;286(8):6233-40. Epub 2010 Dec 8. PMID:21147775 doi:10.1074/jbc.M110.179184</ref> | ||
Compounds were experimentally used to test for inhibitory strength and several key conclusions were made. SAH is non-selective and therefore inhibits eukaryotic, bacterial and viral DENV, WNV, human RNA, DNA, and histone MTases. Attachment of a benzyl ring increased selectivity for DENV MTase, however extending the aryl group by a length of one carbon reduced inhibition significantly due to hydrophobic steric hindrance, and increased substituent flexibility causing bond attenuation. Meta-substitution on the benzyl moiety caused significant increase in inhibition compared to SAH. Larger bromine and iodine groups, however, showed reduced inhibition suggesting steric hindrance from bulky groups reduces inhibition. The N6-substituted benzy ring with chloro functionality revealed rotation of Phe-133 to accommodate the bulky benzyl group, and strong cation-pi interaction between Arg-163 and the aryl-ring, the overall effect of which was tighter binding and subsequent better inhibition.<ref>J Biol Chem. 2011 Feb 25;286(8):6233-40. Epub 2010 Dec 8. PMID:21147775 doi:10.1074/jbc.M110.179184</ref> | Compounds were experimentally used to test for inhibitory strength and several key conclusions were made. SAH is non-selective and therefore inhibits eukaryotic, bacterial and viral DENV, WNV, human RNA, DNA, and histone MTases. Attachment of a benzyl ring increased selectivity for DENV MTase, however extending the aryl group by a length of one carbon reduced inhibition significantly due to hydrophobic steric hindrance, and increased substituent flexibility causing bond attenuation. Meta-substitution on the benzyl moiety caused significant increase in inhibition compared to SAH. Larger bromine and iodine groups, however, showed reduced inhibition suggesting steric hindrance from bulky groups reduces inhibition. The N6-substituted benzy ring with chloro functionality revealed rotation of Phe-133 to accommodate the bulky benzyl group, and strong cation-pi interaction between Arg-163 and the aryl-ring, the overall effect of which was tighter binding and subsequent better inhibition.<ref>J Biol Chem. 2011 Feb 25;286(8):6233-40. Epub 2010 Dec 8. PMID:21147775 doi:10.1074/jbc.M110.179184</ref> | ||
