4iox

The structure of the herpes simplex virus DNA-packaging motor pUL15 C-terminal nuclease domain provides insights into cleavage of concatemeric viral genome precursors

spinqualitylabelsall models 4iox, resolution 2.46Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 4iox is a 4 chain structure with sequence from Human alphaherpesvirus 1. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 2.458Å Ligands: ACT, PEG, PG4, PGE Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function TRM3_HHV11 Component of the molecular motor that translocates genomic DNA in empty capsid during DNA packaging. Heterodimerizes with small terminase protein to be docked on capsid portal protein. The latter forms a ring in which genomic DNA in translocated into the capsid. May have or induce an endonuclease activity to cleave the genome concatemer after encapsidation. Publication Abstract from PubMed Herpes simplex virus type 1 (HSV-1), the prototypic member of herpesviruses, employs a virally encoded molecular machine called terminase to package viral dsDNA genome into a preformed protein shell. The terminase contains a large subunit that is thought to cleave concatemeric viral DNA during the packaging initiation and completion of each packaging cycle and supply energy to the packaging process via ATP hydrolysis. We have determined the X-ray structure of the C-terminal domain of the terminase large subunit pUL15 (pUL15C) from HSV-1. The structure shows a fold resembling those of bacteriophage terminases, RNases H, integrases, DNA polymerases, and topoisomerases, with an active site clustered with acidic residues. Docking analysis reveals a DNA-binding surface surrounded by flexible loops, indicating considerable conformational changes upon DNA binding. In vitro assay shows that pUL15C possesses non-sequence-specific, Mg2+-dependent nuclease activity. These results suggest that pUL15 uses an RNase-H-like, metal-ion-mediated catalysis mechanism for cleavage of viral concatemeric DNA. The structure reveals extra structural elements in addition to the RNase H-like fold core and variations in local architecture of the nuclease active site, which are conserved in herpesvirus terminases, bear great similarity to the phage T4 gp17, but are distinct from Podovirus and Siphovirus orthologs and cellular RNase H, delineating a new evolutionary lineage among a large family of eukaryotic viruses and simple and complex prokaryotic viruses. The structure of the herpes simplex virus DNA-packaging terminase pUL15 nuclease domain suggests an evolutionary lineage among eukaryotic and prokaryotic viruses.,Sigamani SS, Zhao H, Kamau YN, Baines JD, Tang L J Virol. 2013 Apr 17. PMID:23596306 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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