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.

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 Novel Chimeric β-Lactamase CTX-M-64, a Hybrid of CTX-M-15-Like and CTX-M-14 β-Lactamases, Found in a Shigella sonnei Strain Resistant to Various Oxyimino-Cephalosporins, Including Ceftazidime

2008 ◽  
Vol 53 (1) ◽  
pp. 69-74 ◽  
Author(s):  
Yukiko Nagano ◽  
Noriyuki Nagano ◽  
Jun-ichi Wachino ◽  
Keiko Ishikawa ◽  
Yoshichika Arakawa
Keyword(s):  
Escherichia Coli ◽  
Amino Acids ◽  
Amino Acid ◽  
Homologous Recombination ◽  
Amino Acid Sequence ◽  
Inverted Repeat ◽  
Shigella Sonnei ◽  
Alternative Mechanism ◽  
The Right ◽  
M 14

ABSTRACT The plasmid-mediated novel β-lactamase CTX-M-64 was first identified in Shigella sonnei strain UIH-1, which exhibited resistance to cefotaxime (MIC, 1,024 μg/ml) and ceftazidime (MIC, 32 μg/ml). The amino acid sequence of CTX-M-64 showed a chimeric structure of a CTX-M-15-like β-lactamase (N- and C-terminal moieties) and a CTX-M-14-like β-lactamase (central portion, amino acids 63 to 226), suggesting that it originated by homologous recombination between the corresponding genes. The introduction of a recombinant plasmid carrying bla CTX-M-64 conferred resistance to cefotaxime in Escherichia coli, and the activities of cefotaxime and ceftazidime were restored in the presence of clavulanic acid. Of note, CTX-M-64 production could also confer consistent resistance to ceftazidime, which differs from the majority of CTX-M-type enzymes, which poorly hydrolyze ceftazidime. These results were consistent with the kinetic parameters determined with the purified CTX-M-64 enzyme. The bla CTX-M-64 gene was flanked upstream by an ISEcp1 sequence and downstream by an orf477 sequence. The sequence of the 45-bp spacer region between the right inverted repeat (IRR) of ISEcp1 and bla CTX-M-64 was exactly identical to that of ISEcp1-bla CTX-M-15-like. Moreover, the presence of a putative IRR of ISEcp1 at the right end of truncated orf477 is indicative of an ISEcp1-mediated transposition event in the bla CTX-M-64 gene. The emergence of CTX-M-64 by probable homologous recombination would suggest the natural potential of an alternative mechanism for the diversification of CTX-M-type β-lactamases.

scholarly journals Genetic Functions Promoting Homologous Recombination in Escherichia coli: A Study of Inversions in Phage Λ

Genetics ◽  
1987 ◽  
Vol 115 (1) ◽  
pp. 11-24
Author(s):  
Don G Ennis ◽  
Susan K Amundsen ◽  
Gerald R Smith
Keyword(s):  
Escherichia Coli ◽  
Homologous Recombination ◽  
Molecular Model ◽  
Reca Protein ◽  
Dna Polymerase I ◽  
E Coli ◽  
The Right ◽  
Polymerase I ◽  
Recbcd Enzyme ◽  
A Current

ABSTRACT We have studied homologous recombination in a derivative of phage λ containing two 1.4-kb repeats in inverted orientation. Inversion of the intervening 2.5-kb segment occurred efficiently by the Escherichia coli RecBC pathway but markedly less efficiently by the λ Red pathway or the E. coli RecE or RecF pathways. Inversion by the RecBCD pathway was stimulated by Chi sites located to the right of the invertible segment; this stimulation decreased exponentially by a factor of about 2 for each 2.2 kb between the invertible segment and the Chi site. In addition to RecA protein and RecBCD enzyme, inversion by the RecBC pathway required single-stranded DNA binding protein, DNA gyrase, DNA polymerase I and DNA ligase. Inversion appeared to occur either intra- or intermolecularly. These results are discussed in the framework of a current molecular model for the RecBC pathway of homologous recombination.

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.

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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