Characterization of a host protein associated with brome mosaic virus RNA-dependent RNA polymerase.
The association of host proteins with viral RNA replication proteins has been reported for a number of (+)-strand RNA viruses. However, little is known about the identity or function of these host proteins in viral replication. In this paper we report the characterization of a host protein associated with the RNA-dependent RNA polymerase (RdRp) from brome mosaic virus (BMV)-infected barley. A host protein was specifically and proportionally enriched with BMV RdRp activity through several purification steps. This RdRp-associated host protein reacted with an antiserum prepared against wheat germ eukaryotic translation initiation factor 3 (eIF-3). The RdRp-associated host protein, the p41 subunit of wheat germ eIF-3, and an antigenically related protein from rabbit reticulocyte lysates were all found to bind with high affinity and specificity to BMV-encoded protein 2a, which is involved in viral RNA replication. Moreover, addition of wheat germ eIF-3 or the p41 subunit from wheat germ to BMV RdRp gave a specific and reproducible 3-fold stimulation of (-)-strand RNA synthesis in vivo. These results suggest that the barley analog of eIF-3 subunit p41, or a closely related protein, associates with BMV RdRp in vivo and is involved in BMV RNA replication. This observation and the established role of translation factors in bacteriophage Q beta RdRp suggest that association with translation factors may be a general feature of RNA replication by (+)-strand RNA viruses.
Quadt
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Institute for Molecular Virology, University of Wisconsin-Madison 53706.
Kao
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Browning
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Hershberger
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RP
Ahlquist
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P
D000818:Animals; D002850:Chromatography, Gel; D002852:Chromatography, Ion Exchange; D039621:Eukaryotic Initiation Factor-3; D001467:Hordeum / Q000382:microbiology; D007700:Kinetics; D008970:Molecular Weight; D009029:Mosaic Viruses / Q000201:enzymology* / Q000302:isolation & purification; D010448:Peptide Initiation Factors / Q000302:isolation & purification / Q000378:metabolism; D010940:Plant Proteins / Q000302:isolation & purification / Q000378:metabolism*; D014176:Protein Biosynthesis; D012324:RNA-Dependent RNA Polymerase / Q000302:isolation & purification / Q000378:metabolism*; D011817:Rabbits; D012156:Reticulocytes / Q000378:metabolism; D014908:Triticum / Q000378:metabolism
D039621:Eukaryotic Initiation Factor-3; D010448:Peptide Initiation Factors; D010940:Plant Proteins; D012324:RNA-Dependent RNA Polymerase