Structural highlights
Function[CAPSD_CPVBM] Capsid protein self-assembles to form an icosahedral capsid with a pseudo T=2 symmetry, about 50 nm in diameter, and consisting of 120 capsid proteins. The capsid encapsulates the genomic RNA. Publication Abstract from PubMedmRNA transcription in dsRNA viruses is a highly regulated process but the mechanism of this regulation is not known. Here, by nucleoside triphosphatase (NTPase) assay and comparisons of six high-resolution (2.9-3.1 A) cryo-electron microscopy structures of cytoplasmic polyhedrosis virus with bound ligands, we show that the large sub-domain of the guanylyltransferase (GTase) domain of the turret protein (TP) also has an ATP-binding site and is likely an ATPase. S-adenosyl-L-methionine (SAM) acts as a signal and binds the methylase-2 domain of TP to induce conformational change of the viral capsid, which in turn activates the putative ATPase. ATP binding/hydrolysis leads to an enlarged capsid for efficient mRNA synthesis, an open GTase domain for His217-mediated guanylyl transfer, and an open methylase-1 domain for SAM binding and methyl transfer. Taken together, our data support a role of the putative ATPase in mediating the activation of mRNA transcription and capping within the confines of the virus. A putative ATPase mediates RNA transcription and capping in a dsRNA virus.,Yu X, Jiang J, Sun J, Zhou ZH Elife. 2015 Aug 4;4:e07901. doi: 10.7554/eLife.07901. PMID:26240998[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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