@article{mbs:/content/journal/jgv/10.1099/vir.0.80491-0, author = "Tourís-Otero, Fernando and Martínez-Costas, José and Vakharia, Vikram N. and Benavente, Javier", title = "Characterization of the nucleic acid-binding activity of the avian reovirus non-structural protein σNS", journal= "Journal of General Virology", year = "2005", volume = "86", number = "4", pages = "1159-1169", doi = "https://doi.org/10.1099/vir.0.80491-0", url = "https://www.microbiologyresearch.org/content/journal/jgv/10.1099/vir.0.80491-0", publisher = "Microbiology Society", issn = "1465-2099", type = "Journal Article", abstract = "The avian reovirus non-structural protein σNS has previously been shown to bind single-stranded (ss) RNA in vitro in a sequence-independent manner. The results of the present study further reveal that σNS binds poly(A), poly(U) and ssDNA, but not poly(C), poly(G) or duplex nucleic acids, suggesting that σNS has some nucleotide-sequence specificity for ssRNA binding. The current findings also show that σNS is present in large ribonucleoprotein complexes in the cytoplasm of avian reovirus-infected cells, indicating that it exists in intimate association with ssRNAs in vivo. Removal of RNA from the complexes generates a σNS protein form that sediments between 4·5 and 7 S, suggesting that RNA-free σNS associates into small oligomers. Expression and purification of recombinant σNS in insect cells allowed us to generate specific antibodies and to perform a variety of assays. The results of these assays revealed that: (i) RNA-free σNS exists as homodimers and homotrimers; (ii) the minimum RNA size for σNS binding is between 10 and 20 nt; (iii) σNS does not have a preference for viral mRNA sequences; and (iv) its RNA-binding activity is conformation-dependent. Baculovirus expression of point and deletion σNS mutants in insect cells showed that the five conserved basic amino acids that are important for RNA binding and ribonucleoprotein-complex formation are dispersed throughout the entire σNS sequence, suggesting that this protein binds ssRNA through conformational domains. Finally, the properties of the avian reovirus protein σNS are compared with those of its mammalian reovirus counterpart.", }