Sequence and organization of southern bean mosaic virus genomic RNA.

The genomic RNA sequence of the cowpea strain of southern bean mosaic virus (SBMV-C) has been determined. The genome is 4194 nucleotides in length and has four open reading frames. A 5' proximal open frame, from base 49 to base 603, corresponds to the length of the P4 proteins translated in cell-free extracts from full-length and smaller virion RNA. The largest open frame extends from base 570 to base 3437 and encodes the two largest proteins translated in cell-free extracts from full-length virion RNA. Segments of this open reading frame's predicted amino acid sequence resemble those of known viral RNA polymerases, ATP-binding proteins, and viral genome-linked proteins. A third open frame extends from base 1895 to base 2380 and has not been correlated with an in vitro translation product. The fourth open reading frame is located in the 3' terminal region of the genome extending from base 3217 to base 4053. This frame encodes the SBMV capsid protein which is translated from subgenomic, virion RNA.