2XHW: Hcv-J4 Ns5b Polymerase Trigonal Crystal Form

The hepatitis C virus (HCV) NS5b protein is an RNA-dependent RNA polymerase essential for replication of the viral RNA genome. In vitro and presumably in vivo, NS5b initiates RNA synthesis by a de novo mechanism. Different structural elements of NS5b have been reported to participate in RNA synthesis, especially a so-called "beta-flap" and a C-terminal segment (designated "linker") that connects the catalytic core of NS5b to a transmembrane anchor. High concentrations of GTP have also been shown to stimulate de novo RNA synthesis by HCV NS5b. Here we describe a combined structural and functional analysis of genotype 1 HCV-NS5b of strains H77 (subtype 1a), for which no structure has been previously reported, and J4 (subtype 1b). Our results highlight the linker as directly involved in lifting the first boundary to processive RNA synthesis, the formation of the first dinucleotide primer. The transition from this first dinucleotide primer state to processive RNA synthesis requires removal of the linker and of the beta-flap with which it is shown to strongly interact in crystal structures of HCV NS5b. We find that GTP specifically stimulates this transition irrespective of its incorporation in neosynthesized RNA.
PDB ID: 2XHWDownload
MMDB ID: 89616
PDB Deposition Date: 2010/6/21
Updated in MMDB: 2011/10
Experimental Method:
x-ray diffraction
Resolution: 2.66  Å
Source Organism:
Similar Structures:
Biological Unit for 2XHW: monomeric; determined by software (PISA)
Molecular Components in 2XHW
Label Count Molecule
Protein (1 molecule)
RNA-directed RNA Polymerase
Molecule annotation
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Citing MMDB