Expression and characterization of an RNA capping enzyme encoded by Chlorella virus PBCV-1

We report that the A103R protein of Chlorella virus PBCV-1 is an mRNA capping enzyme that catalyzes the transfer of GMP from GTP to the 5' diphosphate end of RNA. This is a two-step reaction in which the enzyme first condenses with GTP to form a covalent enzyme-GMP intermediate and then transfe...

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Bibliographic Details
Published in:Journal of Virology 1996-10, Vol.70 (10), p.6658-6664
Main Authors: Ho, C.K. (University of Nebraska, Lincoln, NE.), Van Etten, J.L, Shuman, S
Format: Article
Language:English
Subjects:
ACTIVIDAD ENZIMATICA
ACTIVITE ENZYMATIQUE
ARN
CHLORELLA
Chlorella - virology
Chlorella virus
Escherichia coli - genetics
NUCLEOTIDE
NUCLEOTIDOS
Nucleotidyltransferases - genetics
Plant Viruses - enzymology
PURIFICACION
PURIFICATION
Recombinant Proteins - biosynthesis
Recombinant Proteins - genetics
Recombinant Proteins - metabolism
RNA, Viral - metabolism
Sequence Analysis
TRANSFERASAS
TRANSFERASE
Viral Proteins - biosynthesis
Viral Proteins - genetics
Viral Proteins - metabolism
VIRUS DE LAS PLANTAS
VIRUS DES VEGETAUX
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Summary:We report that the A103R protein of Chlorella virus PBCV-1 is an mRNA capping enzyme that catalyzes the transfer of GMP from GTP to the 5' diphosphate end of RNA. This is a two-step reaction in which the enzyme first condenses with GTP to form a covalent enzyme-GMP intermediate and then transfers the GMP to an RNA acceptor to form a GpppN cap. Purified recombinant A103R is a 38-kDa monomer that lacks RNA (guanine-7-) methyltransferase activity. With respect to its size, amino acid sequence, and biochemical properties, A103R is more closely related to the yeast RNA guanylyltransferases than it is to the multifunctional capping enzymes coded for by other large DNA viruses--the poxviruses and African swine fever virus. We surmise that in order to cap its transcripts, PBCV-1 must either encode additional 5' processing activities or else rely on the host alga to provide these functions
ISSN:0022-538X
1098-5514
DOI:10.1128/jvi.70.10.6658-6664.1996