MYCOPLASMA VIRUS P1 HAS A LINEAR, DOUBLE-STRANDED DNA GENOME WITH INVERTED TERMINAL REPEATS

Mycoplasma virus P1 is a tailed, polyhedral virus isolated from Mycopl asma pulmonis. To characterize the P1 genome, stocks of virus were pre pared free of host cell nucleic acids. A single DNA species of 11.3 kb that was shown by plaque hybridization to be of P1 origin was extract ed from the virus. Efficient isolation of P1 DNA required digestion wi th proteolytic enzymes prior to phenol extraction. Although P1 DNA was double-stranded and linear following such treatment, it was resistant to digestion with the 5'-specific lambda exonuclease. Electron micros copic analysis indicated that globular material is complexed to the en ds of P1 DNA. The globular material was not observed on protease-treat ed P1 DNA molecules, suggesting that it is composed of protein. Remova l of the putative terminal protein by chemical treatment allowed the c loning of the P1 DNA ends, and nucleotide sequence analysis revealed t hat these ends contain a 350-bp inverted terminal repeat. (C) 1995 Aca demic Press, Inc.