2pus
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Unprecedented activation mechanism of a non-canonical RNA-dependent RNA polymerase
OverviewOverview
Two lineages of viral RNA-dependent RNA polymerases (RDRPs) differing in, the organization (canonical vs. noncanonical) of the palm subdomain have, been identified. Phylogenetic analyses indicate that both lineages, diverged at a very early stage of the evolution of the enzyme [Gorbalenya, AE, Pringle FM, Zeddam JL, Luke BT, Cameron CE, Kalmakoff J, Hanzlik TN, Gordon KH, Ward VK (2002) J Mol Biol 324:47-62]. Here, we report the x-ray, structure of a noncanonical birnaviral RDRP, named VP1, in its free form, bound to Mg(2+) ions, and bound to a peptide representing the, polymerase-binding motif of the regulatory viral protein VP3. The, structure of VP1 reveals that the noncanonical connectivity of the palm, subdomain maintains the geometry of the catalytic residues found in, canonical polymerases but results in a partial blocking of the active site, cavity. The VP1-VP3 peptide complex shows a mode of polymerase activation, in which VP3 binding promotes a conformational change that removes the, steric blockade of the VP1 active site, facilitating the accommodation of, the template and incoming nucleotides for catalysis. The striking, structural similarities between birnavirus (dsRNA) and the, positive-stranded RNA picornavirus and calicivirus RDRPs provide evidence, supporting the existence of functional and evolutionary relationships, between these two virus groups.
About this StructureAbout this Structure
2PUS is a Protein complex structure of sequences from Infectious bursal disease virus. Full crystallographic information is available from OCA.
ReferenceReference
Activation mechanism of a noncanonical RNA-dependent RNA polymerase., Garriga D, Navarro A, Querol-Audi J, Abaitua F, Rodriguez JF, Verdaguer N, Proc Natl Acad Sci U S A. 2007 Dec 18;104(51):20540-5. Epub 2007 Dec 11. PMID:18077388
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