Genome organization of Spβ c2 bacteriophage carrying the thyP3 gene

Abstract

Thymine auxotrophs of Bacillus subtilis strains lysogenic for temperate bacteriophage SPβ c2 were transformed to prototrophy by DNA from related phage Φ3T. During transformation, the Φ3T-encoded thymidylate synthetase gene, thyP3, became integrated into the extreme right end of the SPβ c2 prophage near the bacterial citK gene. Upon heat induction, the transformed B. subtilis cells released SPβ c2T phages that could lysogenize thymine auxotrophs and convert them to prototrophy. Comparison of restriction endonuclease fragments of DNAs from SPβ c2 and SPβ c2T phages revealed that the latter contained a large region of deletion and substitution near the center of the chromosome. This region included the phage attachment site on the SPβ c2 genome.