2JLG: Structural Explanation For The Role Of Mn In The Activity Of Phi6 Rna-Dependent Rna Polymerase

Citation:
Abstract
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.
PDB ID: 2JLGDownload
MMDB ID: 67676
PDB Deposition Date: 2008/9/9
Updated in MMDB: 2012/12
Experimental Method:
x-ray diffraction
Resolution: 2.8  Å
Source Organism:
Similar Structures:
Biological Unit for 2JLG: dimeric; determined by author and by software (PISA)
Molecular Components in 2JLG
Label Count Molecule
Protein (1 molecule)
1
RNA-directed RNA Polymerase(Gene symbol: pol)
Molecule annotation
Nucleotide(1 molecule)
1
5'-d(*dt DT DT DC Dcp)-3'
Molecule annotation
Chemical (1 molecule)
1
1
* Click molecule labels to explore molecular sequence information.

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