Genome organization of RNA tumor viruses II. Physical maps of in vitro-synthesized Moloney murine leukemia virus double-stranded DNA by restriction endonucleases

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Abstract
Physical maps of the genome of Moloney murine leukemia virus (M-MLV) DNA were constructed by using bacterial restriction endonucleases. The in vitro-synthesized M-MLV double-stranded DNA was used as the source of the viral DNA. Restriction endonucleases Sal I and Hind III cleave viral DNA at only 1 site and, thus, generate 2 DNA fragments. The 2 DNA fragments generated by Sal I are Sal IA (MW, 3.5 .times. 106) and Sal IB (MW, 2.4 .times. 106) and by Hind III are Hind IIIA (MW, 3.6 .times. 106) and Hind IIIB (MW, 2.3 .times. 106). Restriction endonuclease Bam I generates 4 fragments of MW of 2.1 .times. 106 (Bam IA), 2 .times. 106 (Bam IB), 1.25 .times. 106 (Bam IC) and 0.21 .times. 106 (Bam ID), but restriction endonuclease Hpa I cleaves the M-MLV double-stranded DNA twice to give 3 fragments of MW of 4.4 .times. 106 (Hpa IA), 0.84 .times. 106 (Hpa IB) and 0.74 .times. 106 (Hpa IC). Digestion of M-MLV double-stranded DNA with restriction endonuclease Sma I produces 4 fragments of MW of 3.9 .times. 106 (Sma IA), 1.3 .times. 106 (Sma IB), 0.28 .times. 106 (Sma IC) and 0.21 .times. 106 (Sma ID). A mixture of restriction endonucleases Bgl I and Bgl II (Bgl I + II) cleaves the viral DNA at 4 sites generating 5 fragments of approximate MW of 2 .times. 106 (Bgl + IIA), 1.75 .times. 106 (Bgl I + IIB), 1.25 .times. 106 (Bgl I + IIC), 0.40 .times. 106 (Bgl I + IID) and 0.31 .times. 106 (Bgl I + IIE). The order of the fragments in relation to the 5'' end and 3'' end of the genome was determined either by using fractional-length M-MLV double-stranded DNA for digestion by restriction endonucleases or by redigestion of Sal IA, Sal IB, Hind IIIA and Hind IIIB fragments with other restriction endonucleases. A number of other restriction endonucleases that cleave in vitro-synthesized M-MLV double-stranded DNA were also listed.