Cleavage map of linear mouse sarcoma virus DNA.

Abstract

Proviral DNA transcribed from the RNA of Moloney murine sarcoma virus was isolated from newly infected [mouse embryo fibroblast NIH/3T3] cells. Three forms of viral DNA were observed: a linear double-stranded form of 3.4 .times. 106 daltons which constituted the major viral DNA species in the cell, and is thought to be a complete transcript (monomer) of viral RNA; a fast-sedimenting viral DNA bigger than the monomeric unit which can be integrated provirus or concatamers; and covalently closed circles of monomer size representing .ltoreq. 5% of the total viral DNA in the cell. The linear viral DNA was tested for its susceptibility to restriction endonucleases [EcoRI, BamHI, HindIII, HaeII and HincII] by electrophoretic analysis of the digestion products and their identification by hybridization with viral RNA or c[complementary]DNA probes. The linear DNA is not cleaved by EcoRI and BamHI. It is cleaved into 2 fragments by HindIII and HaeII and into 3 fragments by HincII. The fragments of the viral DNA added up to .apprx. 3.4 .times. 106 daltons; this and the uniform size of the linear DNA indicated that the viral DNA has unique ends and a complexity of 3.4 .times. 106 daltons. The different cleavage fragments were ordered with respect to each other and the 3'' end of the viral RNA. The fragments from both ends of the linear DNA can be hybridized to sequence(s) at the 3'' end of murine sarcoma virus RNA. A short redundant sequence probably exists at both termini of the genome.