Tolerated variations in a genome: the case of closely related Bacillus phages PZA, phi 29 and phi 15--a review

Restriction-site analysis was used to estimate the relationship of bacteriophages PZA, phi 29 and phi 15. Complete nucleotide sequences of PZA and luminal diameter 29 genomes were compared and tolerated variations were assessed. Most of the base-pair changes are silent nucleotide substitutions in the third position of codons but amino acid changing substitutions are also observed. The terminal portions of the phage genomes diverged faster than their central parts. Gene mutations in phage PZA were induced by hydroxylamine and their frequency was compared with the evolutionary mutability.