2vbc | pdb_00002vbc
CRYSTAL STRUCTURE OF THE NS3 PROTEASE-HELICASE FROM DENGUE VIRUS
Structural highlights
Function[Q2TN89_9FLAV] Envelope protein E binding to host cell surface receptor is followed by virus internalization through clathrin-mediated endocytosis. Envelope protein E is subsequently involved in membrane fusion between virion and host late endosomes. Synthesized as a homodimer with prM which acts as a chaperone for envelope protein E. After cleavage of prM, envelope protein E dissociate from small envelope protein M and homodimerizes (By similarity).[SAAS:SAAS026470_004_099774] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedSeveral flaviviruses are important human pathogens, including dengue virus, a disease against which neither a vaccine nor specific antiviral therapies currently exist. During infection, the flavivirus RNA genome is translated into a polyprotein, which is cleaved into several components. Nonstructural protein 3 (NS3) carries out enzymatic reactions essential for viral replication, including proteolysis of the polyprotein through its serine protease N-terminal domain, with a segment of 40 residues from the NS2B protein acting as a cofactor. The ATPase/helicase domain is located at the C terminus of NS3. Atomic structures are available for these domains separately, but a molecular view of the full-length flavivirus NS3 polypeptide is still lacking. We report a crystallographic structure of a complete NS3 molecule fused to 18 residues of the NS2B cofactor at a resolution of 3.15 A. The relative orientation between the protease and helicase domains is drastically different than the single-chain NS3-NS4A molecule from hepatitis C virus, which was caught in the act of cis cleavage at the NS3-NS4A junction. Here, the protease domain sits beneath the ATP binding site, giving the molecule an elongated shape. The domain arrangement found in the crystal structure fits nicely into an envelope determined ab initio using small-angle X-ray scattering experiments in solution, suggesting a stable molecular conformation. We propose that a basic patch located at the surface of the protease domain increases the affinity for nucleotides and could also participate in RNA binding, explaining the higher unwinding activity of the full-length enzyme compared to that of the isolated helicase domain. Crystal structure of the NS3 protease-helicase from dengue virus.,Luo D, Xu T, Hunke C, Gruber G, Vasudevan SG, Lescar J J Virol. 2008 Jan;82(1):173-83. Epub 2007 Oct 17. PMID:17942558[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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