An Escherichia coli gene required for bacteriophage P2-lambda interference.

The gene old of bacteriophage P2 is known to (i) cause interference with phage lambda growth; (ii) kill recB- mutants of Escherichia coli after P2 infection; and (iii) determine increased sensitivity of P2 lysogenic cells to X-ray irradiation. In all of these phenomena, inhibition of protein synthesis occurs. We have isolated bacterial mutants, named pin (P2 interference), able to suppress all of the above-mentioned phenomena caused by the old+ gene product and the concurrent protein synthesis inhibition. Pin mutations are recessive, map at 12 min on the E. coli map, and identify a new gene. Satellite bacteriophage P4 does not plate on pin-3 mutant strains and causes cell lethality and protein synthesis inhibition in such mutants. P4 mutants able to grow on pin-3 strains have been isolated.     

The immunity (imm) gene of Escherichia coli bacteriophage T4.

The immunity (imm) gene of the Escherichia coli bacteriophage T4 effects exclusion of phage superinfecting cells already infected with T4. A candidate for this gene was placed under the control of the lac regulatory elements in a pUC plasmid. DNA sequencing revealed the presence of an open reading frame encoding a very lipophilic 83-residue (or 73-residue, depending on the unknown site of translation initiation) polypeptide which most likely represents a plasma membrane protein. This gene could be identified as the imm gene because expression from the plasmid caused exclusion of T4 and because interruption of the gene in the phage genome resulted in a phage no longer effecting superinfection immunity. It was found that the fraction of phage which was excluded upon infection of cells possessing the plasmid-encoded Imm protein ejected only about one-half of their DNA. Therefore, the Imm protein inhibited, directly or indirectly, DNA ejection.     

X-ray sensitivity of Escherichia coli lysogenic for bacteriophage P2.

Summary Strains of Escherichia coli C or K lysogenic for the non-inducible phage P2 show a lower survival following X-ray irradiation as compared to nonlysogenic strains. This difference in X-ray sensitivity is not accompanied by a significant difference in X-ray induced mutability. The capacity of X-irradiated P2 lysogens to multiply any of a number of unirradiated infecting phages is severely impaired. These effects of X-ray treatment can be most simply explained as a consequence of the fact that protein and RNA syntheses are strongly inhibited in P2 lysogens after X-irradiation. All the above events specifically occurring in X-rayed P2 lysogens are dependent on the P2 gene old.     

ADP ribosylation of Escherichia coli RNA polymerase is nonessential for bacteriophage T4 development.

The bacteriophage T4-induced alt and mod gene products covalently add ADP-ribose to the Escherichia coli RNA polymerase alpha polypeptides; phage carrying either an alt or a mod mutation are viable. A genetic cross between T4alt and T4mod phages yielded alt mod recombinant progeny which could not ADP ribosylate RNA polymerase at all, yet grew apparently normally. Thus, ADP ribosylation of RNA polymerase appeared to be nonessential for T4 development (at least in E. coli B/r and E. coli CR63), even though the phage has evolved two distinct enzymes to catalyze this reaction.     

Host RecJ is required for growth of P22 erf bacteriophage.

Growth of bacteriophage P22 erf is known to require host RecA recombination function. We show that the RecA function is necessary but not sufficient to restore the plaque-forming ability of phage P22 erf; such mutant phage also requires host RecJ function. The residual efficiency of plaquing of P22 erf in a recJ background (0.03%) is completely abolished in recJ recB hosts (< 0.001%), suggesting that the RecBCD nuclease can provide an alternative function allowing phage growth. One tentative explanation is that circularization of P22 erf DNA mostly proceeds through the RecF pathway of recombination; however, less efficient circularization via the RecBCD pathway may also occur. In a recJ background, lysates obtained upon induction of an erf prophage show reduced yield (10%), suggesting that growth of P22 erf may require host RecJ in a step(s) other than circularization of phage DNA.     

Size distribution of DNA replicative intermediates in bacteriophage P4 and in Escherichia coli.

We have tested the hypothesis that Okazaki fragment replicative intermediates have defined termini using as a model system the in vivo DNA replication of the tiny bacteriophage P4. The kinetics of formation of intermediates in P4 DNA replication have been investigated. P4 DNA replication in DNA polymerase I-deficient mutants generates Okazaki fragments with a size distribution similar to that in uninfected cells. When P4-derived Okazaki fragments are resolved by agarose gel electrophoresis, no discrete size classes appear. This finding is incompatible with sequence-specific models of Okazaki fragment formation but supports the view that these replication intermediates are initiated and terminated at random locations on the P4 chromosome.     

Polynucleotide kinase mutant of bacteriophage T4

Summary We report the isolation and biological properties of two T4 phage mutants which are deficient in polynucleotide kinase. These two mutants are wild type with respect to replication, genetic recombination and DNA repair (as measured by sensitivity to UV irradiation, -irradiation and ³²P decay). These negative results suggest that this phage-induced enzyme is not a critical factor in DNA metabolism.     

Transduction of Escherichia coli by bacteriophage P1 in soil.

Transduction of Escherichia coli W3110(R702) and J53(RP4) (10(4) to 10(5) CFU/g of soil) by lysates of temperature-sensitive specialized transducing derivatives of bacteriophage P1 (10(4) to 10(5) PFU/g of soil) (P1 Cm cts, containing the resistance gene for chloramphenicol, or P1 Cm cts::Tn501, containing the resistance genes for chloramphenicol and mercury [Hg]) occurred in soil amended with montmorillonite or kaolinite and adjusted to a -33-kPa water tension. In nonsterile soil, survival of introduced E. coli and the numbers of E. coli transductants resistant to chloramphenicol or Hg were independent of the clay amendment. The numbers of added E. coli increased more when bacteria were added in Luria broth amended with Ca and Mg (LCB) than when they were added in saline, and E. coli transductants were approximately 1 order of magnitude higher in LCB; however, the same proportion of E. coli was transduced with both types of inoculum. In sterile soil, total and transduced E. coli and P1 increased by 3 to 4 logs, which was followed by a plateau when they were inoculated in LCB and a gradual decrease when they were inoculated in saline. Transduction appeared to occur primarily in the first few days after addition of P1 to soil. The transfer of Hg or chloramphenicol resistance from lysogenic to nonlysogenic E. coli by phage P1 occurred in both sterile and nonsterile soils. On the basis of heat-induced lysis and phenotype, as well as hybridization with a DNA probe in some studies, the transductants appeared to be the E. coli that was added. Transduction of indigenous soil bacteria was not unequivocally demonstrated.(ABSTRACT TRUNCATED AT 250 WORDS)