scholarly journals Heteroduplex chain polarity in recombination of phage lambda by the red, RecBCD, RecBC(D-) and RecF pathways.

Genetics ◽  
1991 ◽  
Vol 128 (1) ◽  
pp. 7-22 ◽  
Author(s):  
I Siddiqi ◽  
M M Stahl ◽  
F W Stahl
Keyword(s):  
Escherichia Coli ◽  
Genetic Map ◽  
Bacteriophage Lambda ◽  
The Other ◽  
Genetic Contribution ◽  
Phage Lambda ◽  
Heteroduplex Dna ◽  
Recf Pathway ◽  
The Right ◽  
Parental Information

Abstract We have examined the chain polarity of heteroduplex DNA in unreplicated, bacteriophage lambda splice recombinants when recombination was by the RecBCD, RecBC(D-), or RecF pathway of Escherichia coli or the Red pathway of lambda. For each of these pathways, recombination is activated by the cutting of cos that accompanies chromosome packaging, and is effected by recombination enzymes acting at the right end created by that cutting. For exchanges occurring near cos, one parent makes a lesser physical and genetic contribution than does the other. For each pathway, when the phage carried standard cos, this minority contribution was predominantly on the r chain, ending 5' at the right end of lambda. When standard cos was replaced by a cloned inverted cos located centrally on the standard lambda genetic map, minority contribution was predominantly on the l chain. In each case, the polarity of the overlap was usually that formed by 3' overhangs of parental information and material. These results are discussed in the context of current models of recombination for the different pathways.

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.

scholarly journals Rec-mediated recombinational activity of two adjacent Chi elements in bacteriophage lambda

1985 ◽  
Vol 45 (1) ◽  
pp. 1-8 ◽  
Author(s):  
Ezra Yagil ◽  
Inna Shtromas
Keyword(s):  
Bacteriophage Lambda ◽  
The Other ◽  
The Right

SummaryChi is a sequence of eight nucleotide pairs which stimulate recBC-mediated recombination (Smith, 1983a, b). The effect of two linked Chis on recBC-mediated recombination was tested in bacteriophage lambda. It was noticed that the Chi element located on the right side of the phage chromosome is epistatic on the other Chi. These findings support a model proposed by Stahl et al. (1983) which suggests that the recombination machinery moves unidirectionaly in the phage chromosome from right to left. The results also suggest that in the presence of more than one Chi only the rightmost one stimulates recombination.

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.

Roles for λ Orf and Escherichia coli RecO, RecR and RecF in λ Recombination

Genetics ◽  
1997 ◽  
Vol 147 (2) ◽  
pp. 357-369
Author(s):  
James A Sawitzke ◽  
Franklin W Stahl
Keyword(s):  
Escherichia Coli ◽  
Dna Replication ◽  
Gene Product ◽  
Strand Break ◽  
Bacteriophage Λ ◽  
Recf Pathway ◽  
The Right ◽  
Mutant Cells ◽  
Λ Red ◽  
Red Recombination

Bacteriophage λ lacking its Red recombination functions requires either its own gene product, Orf, or the product of Escherichia coli's recO, recR and recF genes (RecORF) for efficient recombination in recBC sbcB sbcC mutant cells (the RecF pathway). Phage crosses under conditions of a partial block to DNA replication have revealed the following: (1) In the presence of Orf, RecF pathway recombination is similar to λ Red recombination; (2) Orf is necessary for focusing recombination toward the right end of the chromosome as λ is conventionally drawn; (3) RecORF-mediated RecF pathway recombination is not focused toward the right end of the chromosome, which may indicate that RecORF travels along the DNA; (4) both Orf- and RecORF-mediated RecF pathway recombination are stimulated by DNA replication; and (5) low level recombination in the simultaneous absence of Orf and RecORF may occur by a break-copy mechanism that is not initiated by a double strand break. Models for the roles of Orf and RecO, RecR and RecF in recombination are presented.

scholarly journals DELETION AND AMBER MUTANTS OF fla LOCI IN ESCHERICHIA COLI K-12

Genetics ◽  
1976 ◽  
Vol 84 (3) ◽  
pp. 403-421
Author(s):  
Hisato Kondoh ◽  
Haruo Ozeki
Keyword(s):  
Escherichia Coli ◽  
High Temperature ◽  
Genetic Map ◽  
Screening Method ◽  
The Other ◽  
Rapid Screening ◽  
E Coli ◽  
Flagellar Filament ◽  
Rapid Screening Method ◽  
K 12

ABSTRACT A rapid screening method for amber fla mutants of E. coli was devised and many mutants were obtained. In addition, strains with deletions of the fla genes in the his-uvrC region were isolated from high-temperature survivors of a λcI857 lysogen in which the prophage is located between his and fla. Utilizing these mutants, eleven fla genes (I-XI) and one hag gene were identified in the his-uvrc region, in the following order: his-supD-I-II-(III, IV)-V-(VI, VII)-VIII-IX-hag-(X, XI)-uvrC. The fla genes X and XI and hag are located at about 42.5 min and the other fla genes at about 43.0 min on the E. coli genetic map (Bachmann, Low and Taylor 1976). Mutants of fla gene X showed a slight sensitivity to chi phage, although they lack the flagellar filament.

scholarly journals Phage lambda has an analog of Escherichia coli recO, recR and recF genes.

Genetics ◽  
1992 ◽  
Vol 130 (1) ◽  
pp. 7-16 ◽  
Author(s):  
J A Sawitzke ◽  
F W Stahl
Keyword(s):  
Escherichia Coli ◽  
Open Reading Frame ◽  
Phage Lambda ◽  
Reading Frame ◽  
Additional Requirement ◽  
Recf Pathway ◽  
Mutant Cells

Abstract The RecF pathway catalyzes generalized recombination in Escherichia coli that is mutant for recBC, sbcB and sbcC. This pathway operating on conjugational recombination requires the recA, recF, recJ, recN, recO, recQ, recR, ruvA, ruvB and ruvC genes. In contrast, lambda mutant for its own recombination genes, int, red alpha and red beta, requires only the recA and recJ genes to recombine efficiently in recBC sbcB sbcC cells. Deletion of an open reading frame in the ninR region of lambda results in an additional requirement for recO, recR and recF in order to recombine in recBC sbcB sbcC mutant cells. This function, designated orf for recO-, recR- and recF-like function, is largely RecF pathway specific.

scholarly journals Evidence for a Hybrid Genomic Island in Verocytotoxin-Producing Escherichia coli CL3 (Serotype O113:H21) Containing Segments of EDL933 (Serotype O157:H7) O Islands 122 and 48

2004 ◽  
Vol 72 (3) ◽  
pp. 1496-1503 ◽  
Author(s):  
Songhai Shen ◽  
Mariola Mascarenhas ◽  
Kris Rahn ◽  
James B. Kaper ◽  
Mohamed A. Karmal
Keyword(s):  
Escherichia Coli ◽  
Virulence Genes ◽  
Genomic Island ◽  
Virulence Gene ◽  
Genomic Islands ◽  
The Other ◽  
Middle Portion ◽  
Uremic Syndrome ◽  
The Right ◽  
Vtec Strain

ABSTRACT Genomic O island 122 (OI-122) of the verocytotoxin-producing Escherichia coli (VTEC) strain EDL933 contains four putative virulence genes, Z4321, Z4326, Z4332, and Z4333. However, strain CL3 (serotype O113:H21) contains only Z4321, not the other three genes. To determine whether Z4321 is part of a different genomic island in CL3, a region of 27,293 bp up- and downstream of Z4321 was sequenced and found to contain elements of two different EDL933 genomic islands (OI-48 and OI-122) and a Yersinia pestis-like hemolysin/adhesin gene cluster. The region contained OI-48 genes Z1635, Z1636, and Z1637 at the left terminus and Z1641, Z1642, Z1643, and Z1644 at the right. The middle portion consisted of OI-48 gene Z1640, which was separated into three fragments by genomic segments including the Y. pestis cluster and EDL933 OI-122 genes Z4322, Z4321, and Z4318. In a PCR investigation of 36 VTEC strains of different serotypes, intact Z1640 was present in strains of serotypes O157:H7, O26:H11, O103:H2, O111:NM, and O145:NM, which are associated with hemolytic uremic syndrome and outbreaks. In contrast, fragmented Z1640 was seen in strains of nonepidemic serotypes, such as O91:H21 and O113:H21, and in animal serotypes that have not been associated with human disease, indicating that Z1640 might be a virulence gene.

scholarly journals Distribution of Chi-stimulated recombinational exchanges and heteroduplex endpoints in phage lambda.

Genetics ◽  
1989 ◽  
Vol 123 (1) ◽  
pp. 5-17 ◽  
Author(s):  
K C Cheng ◽  
G R Smith
Keyword(s):  
Phage Lambda ◽  
Heteroduplex Dna ◽  
Single Base ◽  
Chi Sequence ◽  
Mismatch Correction ◽  
Single Base Pair ◽  
The Right ◽  
Recombination Pathway ◽  
Recbcd Enzyme ◽  
Lambda Phages

Abstract The recombination hotspot Chi, 5' G-C-T-G-G-T-G-G 3', stimulates the RecBCD recombination pathway of Escherichia coli. We have determined, with precision greater than previously reported, the distribution of Chi-stimulated exchanges around a Chi site in phage lambda. Crosses of lambda phages with single base-pair mutations surrounding a Chi site were conducted in and analyzed on mismatch correction-impaired hosts to preserve heteroduplex mismatches for analysis. Among phages recombinant for flanking markers, Chi stimulated exchanges most intensely in the intervals immediately adjacent to the Chi site, both to its right and to its left. Stimulation fell off abruptly to the right but gradually to the left (with respect to the orientation of the Chi sequence written above). We have also determined that Chi stimulated the formation of heteroduplex DNA, which frequently had one endpoint to the right of Chi and the other endpoint to the left. These data support a model of Chi-stimulated recombination in which RecBCD enzyme cuts DNA immediately to the right of Chi and unwinds DNA to the left of Chi; segments of unwound single-stranded DNA are sometimes, but not always, degraded before synapsis with homologous DNA.

scholarly journals Chain bias in Chi-stimulated heteroduplex patches in the lambda ren gene is determined by the orientation of lambda cos.

Genetics ◽  
1991 ◽  
Vol 129 (3) ◽  
pp. 611-621
Author(s):  
A T Hagemann ◽  
S M Rosenberg
Keyword(s):  
Escherichia Coli ◽  
Homologous Recombination ◽  
Phage Lambda ◽  
Double Chain ◽  
Entry Site ◽  
Normal Orientation ◽  
Dna Chain ◽  
The Right

Abstract Heteroduplex patch recombinants have received information in one DNA chain but have not recombined flanking markers. Evidence regarding which chain is exchanged bears on the structure of recombination intermediates. The direction of travel along DNA of RecBCD recombinase, the central enzyme in the Escherichia coli RecBCD pathway of homologous recombination, is determined in phage lambda by the orientation of the packaging origin, cos. cos is a double-chain cut site which serves as a preferred entry site for RecBCD. Using partially denaturing gels to resolve heteroduplex molecules, we have examined patch recombinants at the lambda ren gene. We report that the transferred information in Chi-stimulated patches at ren can occur on either chain, but is biased to the chain ending 5' at the right of the lambda map (the lambda r chain) in phage carrying cos in its normal orientation. The chain bias switches in favor of the chain that ends 3' at the right (the lambda l chain) when RecBCD travel direction is reversed by inverting cos. We entertain models that accommodate these and other results pertaining to the structure of RecBCD-mediated recombinants.

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