IDENTIFICATION OF A COAT PROTEIN-BINDING SITE ON SOUTHERN BEAN MOSAIC-VIRUS RNA

The cowpea strain of Southern bean mosaic virus (SBMV-C), a T = 3 icos ahedral RNA virus, was dissociated to yield a ribonucleoprotein comple x (RNPC) composed of the viral RNA and coat protein subunits. To deter mine if the coat protein subunits were bound to a specific site on the viral RNA, the RNPC was treated with ribonuclease, and the remaining coat protein-RNA complexes were recovered by filter binding, A single species of RNA was isolated by this procedure and further characterize d by sequencing. The RNA was mapped to nucleotides 1410-1436 of the SB MV-C genome. This region of the viral RNA was predicted to fold into a hairpin with a 4-base loop and a duplex stem of 24 nucleotides. The s tability and specificity of the coat protein-RNA complex isolated from dissociated virus suggest a possible role for this interaction in the selective encapsidation of the viral RNA. (C) 1995 Academic Press, In c.