Structural explanation for the role of Mn2+ in the activity of Φ6 RNA-dependent RNA polymerase

  1. Lookup NU author(s)
  2. Dr Paula Salgado
Author(s)Poranen MM, Salgado PS, Koivunen MRL, Wright S, Bamford DH, Stuart DI, Grimes JM
Publication type Article
JournalNucleic Acids Research
ISSN (print)0305-1048
ISSN (electronic)1362-4962
Full text is available for this publication:
The biological role of manganese (Mn(2+)) has been a long-standing puzzle, since at low concentrations it activates several polymerases whilst at higher concentrations it inhibits. Viral RNA polymerases possess a common architecture, reminiscent of a closed right hand. The RNA-dependent RNA polymerase (RdRp) of bacteriophage 6 is one of the best understood examples of this important class of polymerases. We have probed the role of Mn(2+) by biochemical, biophysical and structural analyses of the wild-type enzyme and of a mutant form with an altered Mn(2+)-binding site (E491 to Q). The E491Q mutant has much reduced affinity for Mn(2+), reduced RNA binding and a compromised elongation rate. Loss of Mn(2+) binding structurally stabilizes the enzyme. These data and a re-examination of the structures of other viral RNA polymerases clarify the role of manganese in the activation of polymerization: Mn(2+) coordination of a catalytic aspartate is necessary to allow the active site to properly engage with the triphosphates of the incoming NTPs. The structural flexibility caused by Mn(2+) is also important for the enzyme dynamics, explaining the requirement for manganese throughout RNA polymerization.
PublisherOxford University Press
PubMed id18940872
Actions    Link to this publication

Altmetrics provided by Altmetric