Initiation of RNA Polymerization and Polymerase Encapsidation by a Small dsRNA Virus

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Collier , A M , Lyytinen , O L , Guo , Y R , Toh , Y , Poranen , M M & Tao , Y J 2016 , ' Initiation of RNA Polymerization and Polymerase Encapsidation by a Small dsRNA Virus ' , PLoS Pathogens , vol. 12 , no. 4 , 1005523 . https://doi.org/10.1371/journal.ppat.1005523

Title: Initiation of RNA Polymerization and Polymerase Encapsidation by a Small dsRNA Virus
Author: Collier, Aaron M.; Lyytinen, Outi L.; Guo, Yusong R.; Toh, Yukimatsu; Poranen, Minna M.; Tao, Yizhi J.
Contributor: University of Helsinki, Biosciences
University of Helsinki, Biosciences
Date: 2016-04
Language: eng
Number of pages: 26
Belongs to series: PLoS Pathogens
ISSN: 1553-7366
URI: http://hdl.handle.net/10138/165830
Abstract: During the replication cycle of double-stranded (ds) RNA viruses, the viral RNA-dependent RNA polymerase (RdRP) replicates and transcribes the viral genome from within the viral capsid. How the RdRP molecules are packaged within the virion and how they function within the confines of an intact capsid are intriguing questions with answers that most likely vary across the different dsRNA virus families. In this study, we have determined a 2.4 angstrom resolution structure of an RdRP from the human picobirnavirus (hPBV). In addition to the conserved polymerase fold, the hPBV RdRP possesses a highly flexible 24 amino acid loop structure located near the C-terminus of the protein that is inserted into its active site. In vitro RNA polymerization assays and site-directed mutagenesis showed that: (1) the hPBV RdRP is fully active using both ssRNA and dsRNA templates; (2) the insertion loop likely functions as an assembly platform for the priming nucleotide to allow de novo initiation; (3) RNA transcription by the hPBV RdRP proceeds in a semi-conservative manner; and (4) the preference of virus-specific RNA during transcription is dictated by the lower melting temperature associated with the terminal sequences. Co-expression of the hPBV RdRP and the capsid protein (CP) indicated that, under the conditions used, the RdRP could not be incorporated into the recombinant capsids in the absence of the viral genome. Additionally, the hPBV RdRP exhibited higher affinity towards the conserved 5'-terminal sequence of the viral RNA, suggesting that the RdRP molecules may be encapsidated through their specific binding to the viral RNAs during assembly.
Subject: DOUBLE-STRANDED-RNA
HEPATITIS-C VIRUS
DE-NOVO INITIATION
VIRAL DIARRHEA VIRUS
CRYSTAL-STRUCTURE
ACTIVE-SITE
ELECTRON CRYOMICROSCOPY
REOVIRUS POLYMERASE-LAMBDA-3
TRANSFERASE-ACTIVITY
BACTERIOPHAGE PHI-6
1183 Plant biology, microbiology, virology
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