Mechanism of RNA 2'-O-methylation: evidence that the catalytic lysine acts to steer rather than deprotonate the target nucleophile.
The weight of current evidence suggests that RNA 2'-O-MTases employ an S(N)2 mechanism with an in-line attack of the target nucleophile upon the methyl group of the AdoMet cofactor. It has been suggested that, like the phosphohydrolytic enzymes, ribozymes, and nucleic acid polymerases, the RNA 2'-O-MTases initially activate the substrate's attacking hydroxyl oxygen by deprotonation. Here, evidence is presented that the vaccinia virus mRNA cap specific 2'-O-MTase VP39 does not promote RNA 2'-oxyanion formation but that instead it acts by steering a hydroxyl oxygen orbital toward the cofactor methyl center.
Li
C
C
Department of Medical Biochemistry and Genetics/Institute of Biosciences and Technology, Texas A&M University System Health Science Center, Houston, Texas 77030, USA.
Xia
Y
Y
Gao
X
X
Gershon
P D
PD
D002247:Carbon Isotopes / Q000378:metabolism; D020134:Catalytic Domain / Q000235:genetics; D006147:Guanine / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D006878:Hydroxides / Q000378:metabolism; D017665:Hydroxyl Radical / Q000378:metabolism; D008239:Lysine / Q000737:chemistry / Q000378:metabolism*; D008780:Methyltransferases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D019906:Nuclear Magnetic Resonance, Biomolecular; D009994:Osmolar Concentration; D011522:Protons; D012315:RNA Caps / Q000378:metabolism; D012367:RNA, Viral / Q000737:chemistry / Q000378:metabolism*; D013379:Substrate Specificity; D014616:Vaccinia virus / Q000201:enzymology / Q000235:genetics / Q000378:metabolism; D014764:Viral Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
D002247:Carbon Isotopes; D006878:Hydroxides; D011522:Protons; D012315:RNA Caps; D012367:RNA, Viral; C088682:VP39 protein, Vaccinia virus; D014764:Viral Proteins; D017665:Hydroxyl Radical; D006147:Guanine; C031356:hydroxide ion; D008780:Methyltransferases; D008239:Lysine