PMID:18614640

Citation	Poranen, MM, Koivunen, MR and Bamford, DH (2008) Nontemplated terminal nucleotidyltransferase activity of double-stranded RNA bacteriophage phi6 RNA-dependent RNA polymerase. J. Virol. 82:9254-64
Abstract	The replication and transcription of double-stranded RNA (dsRNA) viruses occur within a polymerase complex particle in which the viral genome is enclosed throughout the entire life cycle of the virus. A single protein subunit in the polymerase complex is responsible for the template-dependent RNA polymerization activity. The isolated polymerase subunit of the dsRNA bacteriophage phi6 was previously shown to replicate and transcribe given RNA molecules. In this study, we show that this enzyme also catalyzes nontemplated nucleotide additions to single-stranded and double-stranded nucleic acid molecules. This terminal nucleotidyltransferase activity not only is a property of the isolated enzyme but also is detected to take place within the viral nucleocapsid. This is the first time terminal nucleotidyltransferase activity has been reported for a dsRNA virus as well as for a viral particle. The results obtained together with previous high-resolution structural data on the phi6 RNA-dependent RNA polymerase suggest a mechanism for terminal nucleotidyl addition. We propose that the activity is involved in the termination of the template-dependent RNA polymerization reaction on the linear phi6 genome.
Links	PubMed PMC2546882 Online version:10.1128/JVI.01044-08
Keywords	Bacteriophage phi 6/enzymology; Bacteriophage phi 6/genetics; Base Sequence; Models, Biological; Molecular Sequence Data; Nucleocapsid/metabolism; Nucleotides/metabolism; Nucleotidyltransferases/metabolism; Plasmids; RNA Replicase/genetics; RNA Replicase/metabolism; RNA, Double-Stranded/genetics; RNA, Double-Stranded/metabolism; RNA, Viral/genetics; RNA, Viral/metabolism; Templates, Genetic
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
BPPH6:RDRP		GO:0003968: RNA-directed RNA polymerase activity	ECO:0000315:		F		Figure 1A lanes 1 and 2 show that purified wild type P2 catalyzes the polymerization of ssRNA into dsRNA, whereas a mutant P2 does not.	complete CACAO 5981
BPPH6:RDRP		GO:0050265: RNA uridylyltransferase activity	ECO:0000314:		F		Figure 2 shows that purified P2, when in the presence of ssRNA and excess UTP "the P2 polymerase typically added one or two extra nucleotides to a given acceptor ssRNA oligonucleotide"	complete CACAO 5982
BPPH6:RDRP	enables	GO:0003968: RNA-directed 5'-3' RNA polymerase activity	ECO:0000315: mutant phenotype evidence used in manual assertion		F		Seeded From UniProt	complete
BPPH6:RDRP	enables	GO:0050265: RNA uridylyltransferase activity	ECO:0000314: direct assay evidence used in manual assertion		F		Seeded From UniProt	complete

References

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