Behavior of λ Bacteriophage in a Recombination Deficient Strain of Escherichia coli

Abstract

The behavior of X phage in the Rec-strain JC-1569 is compared with that in the Rec+ strain JC-1557. No difference deemed significant was noted in the adsorption rate, latent period, burst size, frequency of lysogenization, and frequency of vegetative phage recombination. The location of the prophage and its mode of insertion in the Rec-lysogen of wild-type X (X+) were inferred to be normal from the results of conjugational crosses. Spontaneous and ultraviolet (UV) irradiation induction of X+ were markedly reduced in the Rec-lysogen. On the other hand, thermal induction of a mutant lambda (Xc1857) lysogen of the Rec-strain was not reduced and was only slightly affected by UV irradiation. Phage subject to inhibition by X immunity failed to multiply in UV-irradiated cells of the Rec-X+ lysogen, whereas those not inhibited by this immunity did multiply. It was concluded that the failure of UV to induce X+ in the Rec-lysogen was not due to damage to the prophage, but rather to the inability of the irradiated cells to respond by lifting immunity. Preliminary evidence indicates that a single mutation confers recombination deficiency and the inability to lift immunity after UV irradiation. Possible relationships between recombination and the lifting of immunity are enumerated.

Inducible error-prone repair in B. subtilis. Final report, September 1, 1979-June 30, 1981

“…Specifically, mutants of ~· coli wh~ch are defect~ve ~n recA· or lexA gene products are unable to induce this error-prone repair system (3,41,42). In addition to error-prone inducible post-replication repair, recA and/or lexA (exrA) mutations prevent error-prone excision ~epair (18), induction of ~ai~ophages (43,44), the induction of the recA gene product [formerly called protein X; (3,45,46,47)] the inhibition of exonuclease V (48), W-or UV reactivation, and W-mutagenesis (3,41,49,50), as well as other physiological changes following the inhibition of DNA replication and/or damage of the DNA (51). The pleiotropic effects of these mutations led Radman (52) to propose the 'SOS' hypothesis.…”

Additive recombination in bacteria.

“…Several lines of evidence indicate that the bacterial and prophage attachment sites consist of sequences which are largely nonhomologous. Two observations suggest that general (Rec-mediated) recombination rarely occurs at these sites: (i) A lysogens of rec+ bacteria are extremely stable; and (ii) A integration occurs as frequently in rec as in rec+ bacteria (18).…”

Genetics of Pseudomonas.

“…This hypothesis is now known to be incorrect for phages such as X and 480 in E. colt, where integration appears to be solely a function of the phage genome (124). Furthermore, the Recmutants of E. colt can be lysogenized with the same frequency as that of the Rec+ form (17). However, mutants of E. coil which have reduced ability to be lysogenized by phage P2 are Rec7 (125).…”

“…cells. Such a difference could result from the presence of by-products of altered DNA metabolism reacting with the repressor (17). It has been shown (136) that, with one of these Les-mutants, DNA synthesis is temperature sensitive, as is the recombination ability.…”