scholarly journals THE INTERACTION OF cos WITH CHI IS SEPARABLE FROM DNA PACKAGING IN recA-recBC-MEDIATED RECOMBINATION OF BACTERIOPHAGE LAMBDA

Genetics ◽  
1983 ◽  
Vol 104 (4) ◽  
pp. 549-570
Author(s):  
Ichizo Kobayashi ◽  
Mary M Stahl ◽  
David Leach ◽  
Franklin W Stahl
Keyword(s):  
Escherichia Coli ◽  
Bacteriophage Lambda ◽  
Dna Packaging ◽  
Bacteriophage Λ ◽  
Entry Site ◽  
Two Component ◽  
General Recombination

ABSTRACT Chi (5′-GCTGGTGG) is a recombinator in RecA- RecBC-mediated recombination in Escherichia coli. In bacteriophage λ vegetative recombination, Chi is fully active only when it is correctly oriented with respect to cos, the site that defines the ends of the packaged chromosome. Here we demonstrate that packaging from cos is not necessary for this cos-Chi interaction. Our evidence suggests that correctly oriented cos is an activator of Chi. cos, as an activator, is (1) dominant over cos  -, (2) active opposite an extensive heterology, (3) able to interact with Chi only when on the same (cis) chromosome, and (4) able to interact with Chi at distances as far as ≥ 20 kb. Thus, cos and Chi form a two-component recombinator system for general recombination. cos may serve as an asymmetric entry site for a recombination enzyme that recognizes Chi in an asymmetric way.

COUPLING WITH PACKAGING EXPLAINS APPARENT NONRECIPROCALITY OF CHI-STIMULATED RECOMBINATION OF BACTERIOPHAGE LAMBDA BY RECA AND RECBC FUNCTIONS

Genetics ◽  
1984 ◽  
Vol 108 (4) ◽  
pp. 773-794
Author(s):  
Ichizo Kobayashi ◽  
Mary M Stahl ◽  
Frederic R Fairfield ◽  
Franklin W Stahl
Keyword(s):  
Escherichia Coli ◽  
Bacteriophage Lambda ◽  
Coupling Model ◽  
Strand Break ◽  
Double Strand Break ◽  
Dna Packaging ◽  
The Other ◽  
Entry Site ◽  
Strong Candidate

ABSTRACT Chi (Χ, 5'-GCTGGTGG) is a recombinator in RecA- and RecBC-mediated recombination in Escherichia coli. In vegetative recombination between two bacteriophage lambda strains, one with and the other without Chi (a  +Χ+  b  - × a-Χob+), the Χ-containing recombinant (a  -Χ+  b  -) is less abundant than the non-Χ-containing recombinant (a+Χob+). Previously this was taken was evidence for nonreciprocality of Χ-stimulated exchange. This inequality, however, is now seen to result from an event at cos (λ's packaging origin) that both activates Chi and initiates DNA packaging. An event at rightward cos leads to activation of leftward Χ on the same chromosome for an exchange to its left. From the resulting circulating dimer (-cos-a+-Χo-b+-cos-a--Χ+-b—), the cos that activated Χ is more likely to be used for rightward packaging initiation than is the cos from the other parent. Consistent with this coupling model is "biased packaging" in λ carrying two cos sites per monomer genome. When their maturation is dependent on dimerization by Χ-stimulated exchange, the phage particles result more often from packaging from the cos that activates Χ than from packaging from the other cos. Since Chi activation and packaging can be uncoupled, we infer that some early and reversible step in packaging activates Χ. A strong candidate for this step is a double-strand break at cos that provides an oriented entry site for a recombinase.

scholarly journals PROPERTIES OF THE TRANSLOCATABLE TETRACYCLINE-RESISTANCE ELEMENT Tn10 IN ESCHERICHIA COLI AND BACTERIOPHAGE LAMBDA

Genetics ◽  
1978 ◽  
Vol 90 (3) ◽  
pp. 427-461
Author(s):  
Nancy Kleckner ◽  
David F Barker ◽  
Donald G Ross ◽  
David Botstein
Keyword(s):  
Escherichia Coli ◽  
Salmonella Typhimurium ◽  
Bacteriophage Lambda ◽  
Tetracycline Resistance ◽  
Polar Effect ◽  
Bacteriophage Λ ◽  
Upstream Gene ◽  
High Frequencies ◽  
Functional Integrity ◽  
Isolation And Characterization

ABSTRACT A number of independent insertions into bacteriophage λ of the translocatable tetracycline-resistance element Tn10 have been isolated and characterized.—The physical positions and relative orientations of several such insertions were determined. Two independent insertions appear to lie in the same orientation at or very near the same site in the cI gene, and two more lie in opposite orientations at or near the same position in or near the rex gene.—Insertions in or near genes cI, rex, and cIII have been characterized genetically for their effects on expression of nearby genes. Tn10 appears to exert a polar effect on expression of distal genes when it is inserted within an operon, even when expression of that operon is under the influence of λ N-function. In addition, Tn10 insertions in rex appear to influence in some way expression of an "upstream" gene, cI.—Lambda derivatives carrying Tn10 give rise to spontaneously occurring, tetracycline-sensitive deletions at high frequencies. It is likely that formation of these deletions is promoted in some way by the Tn10 element.—Lambda::Tn10 phages carrying a Tn10 element that has undergone several successive cycles of translocation since its first isolation and characterization have been analyzed. The results confirm that Tn10 often retains its physical and functional integrity during many cycles of translocation.—Lambda derivatives carrying Tn10 have been used to generate insertions of Tn10 in the chromosome of Escherichia coli. This process is independent of recA function, and seems to be quite analogous to the translocation of Tn10 in Salmonella typhimurium as studied previously.

Restriction of bacteriophage λ by Escherichia coli K

1973 ◽  
Vol 81 (3) ◽  
pp. 395-407 ◽  
Author(s):  
Noreen E. Murray ◽  
P.L. Batten ◽  
K. Murray
Keyword(s):  
Escherichia Coli ◽  
Bacteriophage Λ

scholarly journals Further tests of a recombination model in which chi removes the RecD subunit from the RecBCD enzyme of Escherichia coli.

Genetics ◽  
1990 ◽  
Vol 126 (3) ◽  
pp. 519-533 ◽  
Author(s):  
F W Stahl ◽  
L C Thomason ◽  
I Siddiqi ◽  
M M Stahl
Keyword(s):  
Escherichia Coli ◽  
Dna Sequence ◽  
Dna Packaging ◽  
Lambda Phage ◽  
Recombination Model ◽  
Phage Types ◽  
Point Of Entry ◽  
Reciprocal Recombination ◽  
Recbcd Enzyme ◽  
Lambda Dna

Abstract When one of two infecting lambda phage types in a replication-blocked cross is chi + and DNA packaging is divorced from the RecBCD-chi interaction, complementary chi-stimulated recombinants are recovered equally in mass lysates only if the chi + parent is in excess in the infecting parental mixture. Otherwise, the chi 0 recombinant is recovered in excess. This observation implies that, along with the chi 0 chromosome, two chi + parent chromosomes are involved in the formation of each chi + recombinant. The trimolecular nature of chi +-stimulated recombination is manifest in recombination between lambda and a plasmid. When lambda recombines with a plasmid via the RecBCD pathway, the resulting chromosome has an enhanced probability of undergoing lambda x lambda recombination in the interval into which the plasmid was incorporated. These two observations support a model in which DNA is degraded by Exo V from cos, the sequence that determines the end of packaged lambda DNA and acts as point of entry for RecBCD enzyme, to chi, the DNA sequence that stimulates the RecBCD enzyme to effect recombination. The model supposes that chi acts by ejecting the RecD subunit from the RecBCD enzyme with two consequences. (1) ExoV activity is blocked leaving a highly recombinagenic, frayed duplex end near chi, and (2) as the enzyme stripped of the RecD subunit travels beyond chi it is competent to catalyze reciprocal recombination.

scholarly journals Phage genetic sites involved in lambda growth inhibition by the Escherichia coli rap mutant.

Genetics ◽  
1989 ◽  
Vol 121 (3) ◽  
pp. 401-409
Author(s):  
P Guzmán ◽  
G Guarneros
Keyword(s):  
Escherichia Coli ◽  
Growth Inhibition ◽  
Phage Genome ◽  
Bacteriophage Lambda ◽  
Phage Lambda ◽  
Wild Type ◽  
Attp Site

Abstract The rap mutation of Escherichia coli prevents the growth of bacteriophage lambda. We have isolated phage mutants that compensate for the host deficiency. The mutations, named bar, were genetically located to three different loci of the lambda genome: barI in the attP site, barII in the cIII ea10 region, and barIII within or very near the imm434 region. The level of lambda leftward transcription correlates with rap exclusion. Phage lambda mutants partially defective in the pL promoter or in pL-transcript antitermination showed a Bar- phenotype. Conversely, mutants constitutive for transcription from the pI or pL promoters were excluded more stringently by rap bacteria. We conclude that rap exclusion depends on the magnitude of transcription through the wild type bar loci in the phage genome.

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