The 1.85 A structure of vaccinia protein VP39: a bifunctional enzyme that participates in the modification of both mRNA ends.
VP39 is a bifunctional vaccinia virus protein that acts as both an mRNA cap-specific RNA 2'-O-methyltransferase and a poly(A) polymerase processivity factor. Here, we report the 1.85 A crystal structure of a VP39 variant complexed with its AdoMet cofactor. VP39 comprises a single core domain with structural similarity to the catalytic domains of other methyltransferases. Surface features and mutagenesis data suggest two possible RNA-binding sites with novel underlying architecture, one of which forms a cleft spanning the region adjacent to the methyltransferase active site. This report provides a prototypic structure for an RNA methyltransferase, a protein that interacts with the mRNA 5' cap, and an intact poxvirus protein.
Hodel
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AE
Howard Hughes Medical Institute, Baylor College of Medicine, Houston, Texas 77030, USA.
Gershon
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PD
Shi
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Quiocho
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FA
D001665:Binding Sites / Q000502:physiology; D005075:Biological Evolution; D018360:Crystallography, X-Ray; D007091:Image Processing, Computer-Assisted; D008780:Methyltransferases / Q000737:chemistry; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D012315:RNA Caps / Q000737:chemistry; D012333:RNA, Messenger / Q000378:metabolism*; D012436:S-Adenosylmethionine / Q000378:metabolism; D014616:Vaccinia virus / Q000737:chemistry / Q000201:enzymology*; D014764:Viral Proteins / Q000737:chemistry* / Q000378:metabolism
D012315:RNA Caps; D012333:RNA, Messenger; C088682:VP39 protein, Vaccinia virus; D014764:Viral Proteins; D012436:S-Adenosylmethionine; D008780:Methyltransferases