Sandbox 1k4r: Difference between revisions
No edit summary |
|||
| Line 16: | Line 16: | ||
In the infectious form of the virus, the envelope protein lays flat on the surface of the virus, forming a smooth coat with icosahedral symmetry. However, when the virus is carried into the cell and into lysozomes, the acidic environment causes the protein to snap into a different shape, assembling into trimeric spike | In the infectious form of the virus, the envelope protein lays flat on the surface of the virus, forming a smooth coat with icosahedral symmetry. However, when the virus is carried into the cell and into lysozomes, the acidic environment causes the protein to snap into a different shape, assembling into trimeric spike | ||
Several hydrophobic amino acids at the tip of this spike, colored bright red here, insert into the lysozomal membrane and cause the virus membrane to fuse with lysozome. | Several hydrophobic amino acids at the tip of this spike, colored bright red here, insert into the lysozomal membrane and cause the virus membrane to fuse with lysozome. | ||
The NS5 protein from dengue virus is bifunctional and contains 900 amino acids. The S-adenosyl methionine transferase activity resides within its N-terminal domain, and residues 270 to 900 form the RNA-dependent RNA polymerase (RdRp) catalytic domain. Viral replication begins with the synthesis of minus-strand RNA from the dengue virus positive-strand RNA genome, which is subsequently used as a template for synthesizing additional plus-strand RNA genomes. This essential function for the production of new viral particles is catalyzed by the NS5 RdRp. Here we present a high-throughput in vitro assay partly recapitulating this activity and the crystallographic structure of an enzymatically active fragment of the dengue virus RdRp refined at 1.85-Å resolution. The NS5 nuclear localization sequences, previously thought to fold into a separate domain, form an integral part of the polymerase subdomains. The structure also reveals the presence of two zinc ion binding motifs. In the absence of a template strand, a chain-terminating nucleoside analogue binds to the priming loop site. These results should inform and accelerate the structure-based design of antiviral compounds against dengue virus | |||
Asp-663 and Asp-664 from motif C of the catalytic site are shown in stick representation and labeled. | |||
high GTP concentration or Mn2+ was necessary for DENV NS5 RNA synthesis | |||
<scene name='56/565763/Active_site_gtp/1'>GTP in active site</scene> | |||
<scene name='56/565763/Ns2b/2'>NS2B</scene> | <scene name='56/565763/Ns2b/2'>NS2B</scene> | ||