Characterization of a host protein associated with brome mosaic virus RNA-dependent RNA polymerase

• Published in: Proceedings of the National Academy of Sciences - PNAS 1993-02, Vol.90 (4), p.1498-1502
• Main Authors: Quadt, R. (University of Wisconsin-Madison, Madison, WI), Kao, C.C, Browning, K.S, Hershberger, R.P, Ahlquist, P
• Format: Article
• Language: English
• Subjects: Animals; Antibodies; Antiserum; Barley; Biochemistry; Biological and medical sciences; brome mosaic virus; BROMOVIRUS; characterization; Chromatography, Gel; Chromatography, Ion Exchange; Electrophoresis; Enzymes; Eukaryotic Initiation Factor-3; Fundamental and applied biological sciences. Psychology; Gels; Grain; Hordeum - microbiology; HORDEUM VULGARE; initiation factor eIF-3; Kinetics; Microbiology; Molecular Weight; Mosaic Viruses - enzymology; Mosaic Viruses - isolation & purification; Peptide Initiation Factors - isolation & purification; Peptide Initiation Factors - metabolism; Plant Proteins - isolation & purification; Plant Proteins - metabolism; Protein Biosynthesis; PROTEINAS VEGETALES; PROTEINE VEGETALE; Proteins; purification; Rabbits; Replicative cycle, interference, host-virus relations, pathogenicity, miscellaneous strains; Resins; Reticulocytes - metabolism; Ribonucleic acid; RNA; RNA Replicase - isolation & purification; RNA Replicase - metabolism; RNA viruses; RNA-directed RNA polymerase; Silver staining; TRANSFERASAS; TRANSFERASE; Triticum - metabolism; Viral RNA; Virology; VIRUS DE LAS PLANTAS; VIRUS DES VEGETAUX
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.90.4.1498

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 eLF-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 vitro. These results suggest that the barley analog of eIF-3 subunit p4l, 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