3er8
Crystal structure of the heterodimeric vaccinia virus mRNA polyadenylate polymerase complex with two fragments of RNA
Structural highlights
FunctionMCE_VACCW Displays methyltransferase, positive regulation of the poly(A) polymerase and transcription elongation activities. Involved in the modification of both mRNA ends and in intermediate and late gene positive transcription elongation. At the mRNAs 5' end, methylates the ribose 2' OH group of the first transcribed nucleotide, thereby producing a 2'-O-methylpurine cap. At the 3' end, functions as a processivity factor which stimulates the activity of the viral poly(A) polymerase VP55 that creates mRNA's poly(A) tail. In the presence of VP39, VP55 does not dissociate from the RNA allowing tail elongation to around 250 adenylates.[1] [2] [3] 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 PubMedVaccinia virus protein VP55 translocates continuously with respect to single-stranded nucleic acid while extending its 3'end. Here, all key sites of polymerase-primer interaction were identified, demonstrating the wrapping or looping of polyadenylation primer around the polymerase during translocation. Side-chain substitutions at one of the sites indicated its requirement for tail extension beyond approximately 12 nucleotides in length, and conformational changes observed upon oligonucleotide binding suggested allosteric connectivity during translocation. Conformational changes in VP39 upon VP55 binding suggested that, within the VP55-VP39 complex, VP39's mRNA 5' cap binding site closes. The crystallographic structure showed a PAPase catalytic center without side-chain substitutions, possessing two metal ions and with all known reactive and catalytic groups represented, fitting a classical two-metal ion mechanism for phosphoryl transfer. Polymerase translocation with respect to single-stranded nucleic acid: looping or wrapping of primer around a poly(A) polymerase.,Li C, Li H, Zhou S, Sun E, Yoshizawa J, Poulos TL, Gershon PD Structure. 2009 May 13;17(5):680-9. PMID:19446524[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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