Osmoregulation of Dimer Resolution at the Plasmid pJHCMW1 mwr Locus by Escherichia coli XerCD Recombination

ABSTRACT Xer-mediated dimer resolution at the mwr site of plasmid pJHCMW1 is osmoregulated in Escherichia coli. Whereas under low-salt conditions, the site-specific recombination reaction is efficient, under high-salt conditions, it proceeds inefficiently. Regulation of dimer resolution is independent of H-NS and is mediated by changes in osmolarity rather than ionic effects. The low level of recombination at high salt concentrations can be overcome by high levels of PepA or by mutating the ARG box to a sequence closer to the E. coli ARG box consensus. The central region of the mwr core recombination site plays a role in regulation of site-specific recombination by the osmotic pressure of the medium.

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Functional Analysis of the Acinetobacter baumannii XerC and XerD Site-Specific Recombinases: Potential Role in Dissemination of Resistance Genes

Antibiotics ◽

10.3390/antibiotics9070405 ◽

2020 ◽

Vol 9 (7) ◽

pp. 405

Author(s):

David L. Lin ◽

German M. Traglia ◽

Rachel Baker ◽

David J. Sherratt ◽

Maria Soledad Ramirez ◽

...

Keyword(s):

Escherichia Coli ◽

Functional Analysis ◽

Acinetobacter Baumannii ◽

Potential Role ◽

Covalent Attachment ◽

Recombination Reaction ◽

Site Specific ◽

Site Specific Recombination ◽

E Coli ◽

Resistant Genes

Modules composed of a resistance gene flanked by Xer site-specific recombination sites, the vast majority of which were found in Acinetobacter baumannii, are thought to behave as elements that facilitate horizontal dissemination. The A. baumannii xerC and xerD genes were cloned, and the recombinant clones used to complement the cognate Escherichia coli mutants. The complemented strains supported the resolution of plasmid dimers, and, as is the case with E. coli and Klebsiella pneumoniae plasmids, the activity was enhanced when the cells were grown in a low osmolarity growth medium. Binding experiments showed that the partially purified A. baumannii XerC and XerD proteins (XerCAb and XerDAb) bound synthetic Xer site-specific recombination sites, some of them with a nucleotide sequence deduced from existing A. baumannii plasmids. Incubation with suicide substrates resulted in the covalent attachment of DNA to a recombinase, probably XerCAb, indicating that the first step in the recombination reaction took place. The results described show that XerCAb and XerDAb are functional proteins and support the hypothesis that they participate in horizontal dissemination of resistant genes among bacteria.

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Functional Analysis of the Acinetobacter baumannii XerC and XerD Site-Specific Recombinases: Potential Role in Dissemination of Resistance Genes

10.20944/preprints202006.0163.v1 ◽

2020 ◽

Author(s):

David L. Lin ◽

German M. Traglia ◽

Rachel Baker ◽

David J. Sherratt ◽

Maria S. Ramirez ◽

...

Keyword(s):

Escherichia Coli ◽

Functional Analysis ◽

Acinetobacter Baumannii ◽

Potential Role ◽

Covalent Attachment ◽

Recombination Reaction ◽

Site Specific ◽

Site Specific Recombination ◽

E Coli ◽

Resistant Genes

Modules composed of a resistance gene flanked by Xer site-specific recombination sites, the vast majority of which were found in Acinetobacter baumannii, are thought to behave as elements that facilitate horizontal dissemination. The xerCAb and xerDAb genes were cloned, and the recombinant clones used to complement the cognate Escherichia coli mutants. The complemented strains supported resolution of plasmid dimers, and, as is the case with E. coli and Klebsiella pneumoniae plasmids, the activity was enhanced when cells were growing in low osmolarity growth medium. Binding experiments showed that partially purified A. baumannii XerC and XerD proteins (XerCAb and XerDAb) bound synthetic Xer site-specific recombination sites, some of them with a nucleotide sequence deduced from existing A. baumannii plasmids. Incubation with suicide substrates resulted in covalent attachment of DNA to a recombinase, probably XerCAb, indicating that the first step in the recombination reaction took place. The results described show that XerCAb and XerDAb are functional proteins that actively participate in horizontal dissemination of resistant genes among bacteria.

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fpr, a Deficient Xer Recombination Site from a Salmonella Plasmid, Fails To Confer Stability by Dimer Resolution: Comparative Studies with the pJHCMW1 mwr Site

Journal of Bacteriology ◽

10.1128/jb.01082-09 ◽

2009 ◽

Vol 192 (3) ◽

pp. 883-887 ◽

Cited By ~ 8

Author(s):

Tung Tran ◽

David J. Sherratt ◽

Marcelo E. Tolmasky

Keyword(s):

Central Region ◽

Comparative Studies ◽

Recombination Site ◽

Binding Region ◽

Site Specific ◽

Site Specific Recombination ◽

A Site

ABSTRACT Salmonella plasmid pFPTB1 includes a Tn3-like transposon and a Xer recombination site, fpr, which mediates site-specific recombination at efficiencies lower than those required for stabilizing a plasmid by dimer resolution. Mutagenesis and comparative studies with mwr, a site closely related to fpr, indicate that there is an interdependence of the sequences in the XerC binding region and the central region in Xer site-specific recombination sites.

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The Escherichia coli Fis Protein Stimulates Bacteriophage λ Integrative Recombination In Vitro

Journal of Bacteriology ◽

10.1128/jb.185.10.3076-3080.2003 ◽

2003 ◽

Vol 185 (10) ◽

pp. 3076-3080 ◽

Cited By ~ 17

Author(s):

Dominic Esposito ◽

Gary F. Gerard

Keyword(s):

Escherichia Coli ◽

Host Cell ◽

Essential Role ◽

Bacteriophage Λ ◽

Site Specific ◽

Site Specific Recombination ◽

E Coli ◽

In Vivo Recombination

ABSTRACT The Escherichia coli nucleoid-associated protein Fis was previously shown to be involved in bacteriophage lambda site-specific recombination in vivo, enhancing the levels of both integrative recombination and excisive recombination. While purified Fis protein was shown to stimulate in vitro excision, Fis appeared to have no effect on in vitro integration reactions even though a 15-fold drop in lysogenization frequency had previously been observed in fis mutants. We demonstrate here that E. coli Fis protein does stimulate integrative lambda recombination in vitro but only under specific conditions which likely mimic natural in vivo recombination more closely than the standard conditions used in vitro. In the presence of suboptimal concentrations of Int protein, Fis stimulates the rate of integrative recombination significantly. In addition, Fis enhances the recombination of substrates with nonstandard topologies which may be more relevant to the process of in vivo phage lambda recombination. These data support the hypothesis that Fis may play an essential role in lambda recombination in the host cell.

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Site-Specific Recombination in the Cyanobacterium Anabaena sp. Strain PCC 7120 Catalyzed by the Integrase of Coliphage HK022

Journal of Bacteriology ◽

10.1128/jb.00368-09 ◽

2009 ◽

Vol 191 (13) ◽

pp. 4458-4464 ◽

Cited By ~ 3

Author(s):

Olga Melnikov ◽

Arieh Zaritsky ◽

Aliza Zarka ◽

Sammy Boussiba ◽

Natalia Malchin ◽

...

Keyword(s):

Integration Host Factor ◽

Specific Gene ◽

Recombination Reaction ◽

Site Specific ◽

Site Specific Recombination ◽

E Coli ◽

Site Specific Integration ◽

Cyanobacterium Anabaena ◽

Anabaena Sp ◽

Pcc 7120

ABSTRACT The integrase (Int) of the λ-like coliphage HK022 catalyzes the site-specific integration and excision of the phage DNA into and from the chromosome of its host, Escherichia coli. Int recognizes two different pairs of recombining sites attP × attB and attL × attR for integration and excision, respectively. This system was adapted to the cyanobacterium Anabaena sp. strain PCC 7120 as a potential tool for site-specific gene manipulations in the cyanobacterium. Two plasmids were consecutively cointroduced by conjugation into Anabaena cells, one plasmid that expresses HK022 Int recombinase and the other plasmid that carries the excision substrate PglnA -attL-T1/T2-attR-lacZ, where T1/T2 are the strong transcription terminators of rrnB, to prevent expression of the lacZ reporter under the constitutive promoter PglnA . The Int-catalyzed site-specific recombination reaction was monitored by the expression of lacZ emanating as a result of T1/T2 excision. Int catalyzed the site-specific excision reaction in Anabaena cells when its substrate was located either on the plasmid or on the chromosome with no need to supply an accessory protein, such as integration host factor and excisionase (Xis), which are indispensable for this reaction in its host, E. coli.

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Instability of Pathogenicity Islands in Uropathogenic Escherichia coli 536

Journal of Bacteriology ◽

10.1128/jb.186.10.3086-3096.2004 ◽

2004 ◽

Vol 186 (10) ◽

pp. 3086-3096 ◽

Cited By ~ 86

Author(s):

Barbara Middendorf ◽

Bianca Hochhut ◽

Kristina Leipold ◽

Ulrich Dobrindt ◽

Gabriele Blum-Oehler ◽

...

Keyword(s):

Escherichia Coli ◽

Direct Repeat ◽

Pathogenicity Islands ◽

Site Specific ◽

Site Specific Recombination ◽

E Coli ◽

Specific Pcr ◽

Specific Pcr Assay ◽

Derivatives Of ◽

Specific Sequences

ABSTRACT The uropathogenic Escherichia coli strain 536 carries at least five genetic elements on its chromosome that meet all criteria characteristic of pathogenicity islands (PAIs). One main feature of these distinct DNA regions is their instability. We applied the so-called island-probing approach and individually labeled all five PAIs of E. coli 536 with the counterselectable marker sacB to evaluate the frequency of PAI-negative colonies under the influence of different environmental conditions. Furthermore, we investigated the boundaries of these PAIs. According to our experiments, PAI II536 and PAI III536 were the most unstable islands followed by PAI I536 and PAI V536, whereas PAI IV536 was stable. In addition, we found that deletion of PAI II536 and PAI III536 was induced by several environmental stimuli. Whereas excision of PAI I536, PAI II536, and PAI V536 was based on site-specific recombination between short direct repeat sequences at their boundaries, PAI III536 was deleted either by site-specific recombination or by homologous recombination between two IS100-specific sequences. In all cases, deletion is thought to lead to the formation of nonreplicative circular intermediates. Such extrachromosomal derivatives of PAI II536 and PAI III536 were detected by a specific PCR assay. Our data indicate that the genome content of uropathogenic E. coli can be modulated by deletion of PAIs.

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Small Plasmids HarboringqnrB19: a Model for Plasmid Evolution Mediated by Site-Specific Recombination atoriTand Xer Sites

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.06036-11 ◽

2012 ◽

Vol 56 (4) ◽

pp. 1821-1827 ◽

Cited By ~ 23

Author(s):

Tung Tran ◽

Patricia Andres ◽

Alejandro Petroni ◽

Alfonso Soler-Bistué ◽

Ezequiel Albornoz ◽

...

Keyword(s):

Escherichia Coli ◽

Nucleotide Sequence ◽

Variable Region ◽

Recombination Site ◽

Sequence Comparisons ◽

Plasmid Evolution ◽

Site Specific ◽

Content Type ◽

Site Specific Recombination ◽

Clinical Strains

ABSTRACTPlasmids pPAB19-1, pPAB19-2, pPAB19-3, and pPAB19-4, isolated fromSalmonellaandEscherichia coliclinical strains from hospitals in Argentina, were completely sequenced. These plasmids include theqnrB19gene and are 2,699, 3,082, 2,989, and 2,702 nucleotides long, respectively, and they share extensive homology among themselves and with other previously described smallqnrB19-harboring plasmids. The genetic environment ofqnrB19in all four plasmids is identical to that in these other plasmids and in transposons such as Tn2012, Tn5387, and Tn5387-like. Nucleotide sequence comparisons among these and previously described plasmids showed a variable region characterized by being flanked by anoriTlocus and a Xer recombination site. We propose that this arrangement could play a role in the evolution of plasmids and present a model for DNA swapping between plasmid molecules mediated by site-specific recombination events atoriTand a Xer target site.

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