SPECIALIZED TRANSDUCING PHAGES DERIVED FROM PHAGE P22 THAT CARRY THE proAB REGION OF THE HOST, SALMONELLA TYPHIMURIUM: GENETIC EVIDENCE FOR THEIR STRUCTURE AND MODE OF TRANSDUCTION

[摘要] Two independently isolated specialized transducing phages, P22 pro-1 and P22 pro-3 , have been studied. Lysates of P22 pro-1 contain a majority of transducing phages which can go through the lytic cycle only in mixed infection; these defective phages transduce by lysogenization in mixed infection and by substitution in single infection. A few of the transducing phages in P22 pro-1 lysates appear to be non-defective, being able to form plaques and to transduce by lysogenization in single infection. Transduction by P22 pro-3 lysates is effected by non-defective transducing phages, which transduce by lysogenization; these lysates also contain a majority of defective phages which do not co-operate in mixed infection. The P22 pro-1 genome is thought to contain an insertion of bacterial DNA longer than the terminal repetition present in P22 wild type, so that at maturation a population of differently defective phages is produced. The exact structure of the P22 pro-3 genome is open to conjecture, but it seems clear that the insertion of bacterial DNA is smaller than that in P22 pro-1 . Both P22 pro-1 and P22 pro-3 are defective in integration at ataA under non-selective conditions, although both integrate on medium that lacks proline.

[学科分类] 医学（综合）