Structure of the RNA-directed RNA polymerase from the cystovirus φ12

Proteins. 2013 Aug;81(8):1479-84. doi: 10.1002/prot.24297. Epub 2013 Jun 1.


We have determined the structure of P2, the self-priming RdRp from cystovirus φ12 in two crystal forms (A, B) at resolutions of 1.7 Å and 2.1 Å. Form A contains Mg(2+) bound at a site that deviates from the canonical noncatalytic position seen in form B. These structures provide insight into the temperature sensitivity of a ts-mutant. However, the tunnel through which template ssRNA accesses the active site is partially occluded by a flexible loop; this feature, along with suboptimal positioning of other structural elements that prevent the formation of a stable initiation complex, indicate an inactive conformation in crystallo.

Keywords: RNA-directed RNA polymerase; bacteriophage; cystovirus; de novo initiation; replication; transcription.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Binding Sites
  • Catalytic Domain
  • Crystallography, X-Ray
  • Cystoviridae / chemistry
  • Cystoviridae / enzymology*
  • Cystoviridae / metabolism
  • Magnesium / metabolism
  • Molecular Conformation
  • RNA / metabolism
  • RNA-Dependent RNA Polymerase / chemistry*
  • RNA-Dependent RNA Polymerase / metabolism


  • RNA
  • RNA-Dependent RNA Polymerase
  • Magnesium