Recombination at ColE1 cer requires the Escherichia coli xerC gene product, a member of the lambda integrase family of site-specific recombinases

Colloms, Sean D.; Sýkora, Peter; Szatmari, George; Sherratt, David J.

doi:10.1128/jb.172.12.6973-6980.1990

Cited by 142 publications

(108 citation statements)

References 37 publications

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“…The putative protein sequence of this ORF, designated Sss, shows a high similarity (Fig. 2) to the Sss protein of P. aeruginosa (71% identity and 83% similarity) (13) and the XerC protein of E. coli (48% identity and 68% similarity) (14). Both XerC and Sss are members of the integrase family of site-specific recombinases.…”

Section: Resultsmentioning

confidence: 93%

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A site-specific recombinase is required for competitive root colonization by Pseudomonas fluorescens WCS365

Dekkers

Phoelich

Fits

et al. 1998

Proc. Natl. Acad. Sci. U.S.A.

129

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A colonization mutant of the efficient rootcolonizing biocontrol strain Pseudomonas fluorescens WCS365 is described that is impaired in competitive root-tip colonization of gnotobiotically grown potato, radish, wheat, and tomato, indicating a broad host range mutation. The colonization of the mutant is also impaired when studied in potting soil, suggesting that the defective gene also plays a role under more natural conditions. A DNA fragment that is able to complement the mutation for colonization revealed a multicistronic transcription unit composed of at least six ORFs with similarity to lppL, lysA, dapF, orf235͞233, xerC͞sss, and the largely incomplete orf238. The transposon insertion in PCL1233 appeared to be present in the orf235͞233 homologue, designated orf240. Introduction of a mutation in the xerC͞sss homologue revealed that the xerC͞sss gene homologue rather than orf240 is crucial for colonization. xerC in Escherichia coli and sss in Pseudomonas aeruginosa encode proteins that belong to the integrase family of site-specific recombinases, which play a role in phase variation caused by DNA rearrangements. The function of the xerC͞sss homologue in colonization is discussed in terms of genetic rearrangements involved in the generation of different phenotypes, thereby allowing a bacterial population to occupy various habitats. Mutant PCL1233 is assumed to be locked in a phenotype that is not well suited to compete for colonization in the rhizosphere. Thus we show the importance of phase variation in microbe-plant interactions.The use of microorganisms, including fluorescent Pseudomonas spp., to protect plants against soil-borne diseases is an alternative for the use of chemical pesticides. The biocontrol activity of these strains usually results from the production of one or more antifungal factors. The application of fluorescent Pseudomonas spp. and other plant-growth-promoting rhizobacteria is hampered by inconsistency of performance in the field (1, 2). Although the mechanisms underlying biocontrol are complex and diverse, the need to bring the plant-growthpromoting rhizobacteria cells and their antifungal factors to the right sites at the right time is universal. The importance of this process, designated as root colonization, is underscored in two studies. Schippers et al. (1) showed that inadequate colonization leads to decreased biocontrol activity, and Bull et al. (3) reported an inverse relation between the number of bacteria present on the wheat root and the number of take-all lesions seen on the plant. For these and other reasons, root colonization is often considered the limiting factor for biocontrol in the rhizosphere (1, 2).Two approaches were used in our laboratory to identify traits involved in root colonization. The first approach is to guess which traits are involved in colonization, isolate mutants in these traits, and then test these mutants for colonization in competition with the parental strain. With this approach, motility (4) and synthesis of the O-antigen of lipopolysa...

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Section: Resultsmentioning

confidence: 93%

“…The Tn5lacZ insertion is located 150 bp downstream of the orf240 start codon. The function of this ORF, designated orf235 in E. coli (14) (29% identity and 53% similarity at the amino acid level) and orf233 in P. aeruginosa 7NSK2 (13) (67% identity and 81.5% similarity at the amino acid level), is unknown.…”

Section: Resultsmentioning

confidence: 99%

A site-specific recombinase is required for competitive root colonization by Pseudomonas fluorescens WCS365

Dekkers

Phoelich

Fits

et al. 1998

Proc. Natl. Acad. Sci. U.S.A.

129

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“…The E. coli chromosome and many high-copy-number plasmids contain recombination sites that can act as targets for the two related recombinases XerC and XerD of the lambda integrase family (Colloms et al, 1990;Blakely et al, 1993). Their chromosomal substrate, dif, is located in the chromosome terminus region at 33.6 min of the E. coli genetic map, between the innermost terminator sites terA and terC (Kuempel et al, 1991).…”

Section: The Terminus Regionmentioning

confidence: 99%

Dynamic bacterial genome organization

Kolstø

1997

Molecular Microbiology

105

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SummaryRecently completed projects of sequencing chromosomal fragments and entire chromosomes, as well as physical mapping of genomes, have opened novel inroads to the understanding of the biology of bacterial genomes. From these studies one may draw some conclusions. (i) The organization of orthologous genes on the bacterial chromosome is not conserved during evolution. (ii) The bacterial genome is more complex and also more flexible than hitherto thought. Genetic elements are sometimes part of the chromosome, while at other times they are independent elements or parts of alternative replicons (e.g. large plasmids). Such replicons, carrying essential genes, now seem to deserve the designation 'secondary chromosomes'. A study of the regulation of replication and segregation of these essential genetic elements will be of great interest.

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“…These natural plasmid recombination sites consist of an approximately 30 bp core site, within which strand exchange occurs, and approximately 200 bp of adjacent accessory sequences . Genetic experiments in Escherichia coli have identified two chromosomally encoded related recombinases, XerC and XerD, which bind co-operatively to core recombination sites (Table 1; Colloms et al, 1990;Blakely et al, 1993). In addition to XerC and XerD, recombination at cer requires two accessory proteins, ArgR and PepA (Stirling et al, 1988;1989).…”

Section: Introductionmentioning

confidence: 99%

DNA sequence of recombinase‐binding sites can determine Xer site‐specific recombination outcome

Blake

Ganguly

Sherratt

1997

Molecular Microbiology

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SummaryXer site-specific recombination functions in the stable inheritance of circular plasmids and bacterial chromosomes. Two related recombinases, XerC and XerD, mediate this recombination, which 'undoes' the potential damage of homologous recombination. Xer recombination on natural plasmid sites is preferentially intramolecular, converting plasmid multimers to monomers. In contrast, recombination at the Escherichia coli recombination site, dif, occurs both intermolecularly and intramolecularly, at least when dif is inserted into a multicopy plasmid. Here the DNA sequence features of a family of core recombination sites in which the XerC-and XerD-binding sites, which are separated by 6 bp, were analysed in order to ascertain what determines whether recombination will be preferentially intramolecular, or will occur both within and between molecules. Sequence changes in either the XerC-or XerD-binding site can alter the recombination outcome. Preferential intramolecular recombination between a pair of recombination sites requires additional accessory DNA sequences and accessory recombination proteins and is correlated with reduced affinities of recombinase binding to recombination core sites, reduced XerC-mediated cleavage in vitro, and an apparent increased overall bending in recombinase-core-site complexes.

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Recombination at ColE1 cer requires the Escherichia coli xerC gene product, a member of the lambda integrase family of site-specific recombinases

Cited by 142 publications

References 37 publications

A site-specific recombinase is required for competitive root colonization by Pseudomonas fluorescens WCS365

A site-specific recombinase is required for competitive root colonization by Pseudomonas fluorescens WCS365

Dynamic bacterial genome organization

DNA sequence of recombinase‐binding sites can determine Xer site‐specific recombination outcome

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