The composition of bean golden mosaic virus and its single-stranded DNA genome.

Bean golden mosaic virus (BGMV) contains predominantly circular single-stranded DNA, but DNA isolation by treating virus with proteinase K results in conversion of the DNA to a linear form. The conversion is inhibited by as little as 0.025% sodium dodecyl sulfate but not by phenylmethylsulfonyl fluoride and does not occur when purified DNA is incubated with proteinase K. Protein is not involved in the covalent structure of BGMV DNA; the conversion appears to be caused by an endonuclease that copurifies with the virus and is resistant to proteinase K. BGMV contains a major capsid protein with an estimated molecular weight of 27,400. Two minor proteins are found, even in the most highly purified virus preparations; their origin and role in virus structure or function are unknown. BGMV particles contain 19% DNA; therefore each geminate particle must contain a single DNA molecule, of which over 90% are circular. The estimated molecular weight of the virus is 3.8 x 10(6).