Terminal proteins and short inverted terminal repeats of the small Bacillus bacteriophage genomes.

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Abstract
The genome of Bacillus phage .vphi.29 contains covalently linked protein at both ends. These DNA terminal proteins are essential for .vphi.29 DNA replication. .vphi.29 terminal protein was isolated separately from each end and their 2-dimensional peptide maps were compared. The 2 proteins were identical. The DNA of 4 phages examined (.vphi.15, Nf, M2Y and GA-1) also contain protein at both ends of the DNA molecules. The chymotryptic peptide maps of these DNA terminal proteins were compared with the map of the .vphi.29 terminal protein. Despite the similarities in molecular size, peptide maps of the terminal proteins show clear differences among the unrelated phages. These results are consistent with the idea that the terminal proteins are encoded by viral DNA rather than by the host chromosome. The nucleotide sequences of the termini of 4 phage DNA were determined and compared with the sequence of .vphi.29 DNA. The sequence data indicate that all of these phage DNA contain short inverted terminal repeats: 5'' A-A-A-G-T-A for .vphi.29 and .vphi.15, 5'' A-A-A-G-T-A-A-G for Nf and M2Y, and 5'' A-A-A-T-A-G-A for GA-1.