Identification of domains in brome mosaic virus RNA-1 and coat protein necessary for specific interaction and encapsidation

• Published in: Journal of Virology 1993-11, Vol.67 (11), p.6406-6412
• Main Authors: Duggal, R, Hall, T.C
• Format: Article
• Language: English
• Subjects: Agronomy. Soil science and plant productions; ARN; Biological and medical sciences; Brome mosaic virus; BROMOVIRUS; Bromovirus - ultrastructure; Capsid - metabolism; Capsid - ultrastructure; CICLO VITAL; CYCLE DE DEVELOPPEMENT; Fundamental and applied biological sciences. Psychology; Morphogenesis; Phytopathology. Animal pests. Plant and forest protection; Plant viruses and viroids; Protein Binding; PROTEINAS; PROTEINE; RNA, Viral - metabolism; RNA, Viral - ultrastructure; RNA-Binding Proteins - metabolism; SECUENCIA NUCLEICA; SEQUENCE NUCLEIQUE; Systematics. Structure, properties and multiplication. Genetics; VIRUS; VIRUS DE LAS PLANTAS; VIRUS DES VEGETAUX
• ISSN: 0022-538X; 1098-5514
• DOI: 10.1128/JVI.67.11.6406-6412.1993

Even though many single-stranded RNAs are present in the cytoplasm of infected cells, encapsidation by brome mosaic virus (BWV) coat protein is specific for BMV RNA. Although the highly conserved 3' region of each of the three BMV genomic RNAs is an attractive candidate for the site of recognition by the coat protein, band shift and UV cross-linking assays in the presence of specific and nonspecific competitors revealed only nonspecific interactions. However, BMV RNA-1 formed a retarded complex (complex I) with the coat protein in the absence of competitors, and two domains of RNA-1 that specifically bound coat protein in a small complex (complex II), presumably early in the encapsidation process, were identified. Strong nonspecific, cooperative binding was observed in the presence of high concentrations of coat protein, suggesting that this provides the mechanism leading to rapid encapsidation seen in vivo. In contrast, no binding to a coat protein mutant lacking the N-terminal 25 amino acids that has been shown to be incapable of encapsidation in vivo (R. Sacher and P. Ahlquist, J. Virol. 63:4545-4552, 1989) was detected in vitro. The use of deletion mutants of RNA-1 revealed the presence of domains within the coding region of protein 1a that formed complexes with purified coat protein. One deletion mutant (B1SX) lacking these domains was only slightly more effective in dissociating RNA-1-coat protein complexes than were nonspecific competitors, further suggesting that regions other than the 3' end can participate in the selective encapsidation of BMV RNAs