Studies of mycoplasma and mycoplasmavirus DNA
The mycoplasmas are a diverse group of prokaryotes characterized by small cell size, relatively small genomes, and complete lack of cell wall. Within the past decade, four types of mycoplasmaviruses have been isolated which can infect certain mycoplasma strains. One of these is a spiroplasmavirus specific for Spiroplasma citri. The others, mycoplasmavirus Groups 1, 2, and 3, are specific for Acholeplasma laidlawii. Some of the properties of a Group 1 and a Group 2 mycoplasmavirus are described. In addition, some properties of the host cell, A. laidlawii, were studied using the viruses as probes. Mycoplasmavirus MVL51, a Group 1 virus, was studied. Electron microscope observations confirm that the MVL51 genome is a single-stranded circular DNA molecule. From contour length measurements, it is calculated that the MVL51 single-stranded DNA genome contains about 4,500 nucleotides and has a molecular weight of 1.5 x 10/sup 6/. Mycoplasmavirus MVL2, a Group 2 virus, was also studied. These studies show that the MVL2 genome is a superhelical covalently-closed circular, double-stranded DNA molecule. Contour length measurements indicate that the MVL2 DNA genome contains 11.8 kilobase pairs and has a molecular weight of 7.8 x 10/sup 6/. The MVL2 DNA has a superhelix density of sigma/sub 0/26/sup 0/ = -0.073. The superhelical MVL2 DNA molecule contains non-base paired regions. A restriction enzyme cleavage map of MVL2 DNA was constructed. A variant of the host cell is also described which is unable to replicate infecting MVL51 DNA beyond the conversion of the infecting single strand to double-stranded replicative forms. The variant, A. laidlawii JA1-REP/sup -/, can still support the growth of Group 2 and Group 3 mycoplasmaviruses. (ERB)
- Research Organization:
- Rochester Univ., NY (USA). Dept. of Radiation Biology and Biophysics
- DOE Contract Number:
- EY-76-C-02-3490
- OSTI ID:
- 6540620
- Report Number(s):
- UR-3490-1437
- Country of Publication:
- United States
- Language:
- English
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