Tn1545: A conjugative shuttle transposon

Courvalin, Patrice; Carlier, C

doi:10.1007/bf00333582

Cited by 120 publications

(68 citation statements)

References 36 publications

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“…Almost all conjugative streptococcal transposable elements described so far, namely, Tn916, Tn918, Tn919, Tn920, Tn925, and TnJS45, show extensive homology (9,12,14,26). Thus, they probably arose from a common ancestor.…”

Section: Discussionmentioning

confidence: 99%

Natural transfer of conjugative transposon Tn916 between gram-positive and gram-negative bacteria

1991

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The conjugative streptococcal transposon Tn916 was found to transfer naturally between a variety of gram-positive and gram-negative eubacteria. Enterococcus faecalis hosting the transposon could serve as a donor for Alcaligenes eutrophus, Citrobacter freundii, and Escherichia coli at frequencies of 10(-6) to 10(-8). No transfer was observed with several phototrophic species. Mating of an E. coli strain carrying Tn916 yielded transconjugants with Bacillus subtilis, Clostridium acetobutylicum, Enterococcus faecalis, and Streptococcus lactis subsp. diacetylactis at frequencies of 10(-4) to 10(-6). Acetobacterium woodii was the only gram-positive organism tested that did not accept the transposon from a gram-negative donor. The results prove the ability of conjugative transposable elements such as Tn916 for natural cross-species gene transfer, thus potentially contributing to bacterial evolution.

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Section: Discussionmentioning

confidence: 99%

Natural transfer of conjugative transposon Tn916 between gram-positive and gram-negative bacteria

1991

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“…(This marker gene was not used in the present work.) An erythromycin resistance gene (ermAM) downstream of amyL allows selection in E. coli and many gram-positive bacteria (9), and a second MCS protected on both sides by strong transcriptional terminators the integration of species-specific plasmid replicons. A similar vector, pERM-ex1, has been constructed for the purpose of gene expression (27).…”

Section: Resultsmentioning

confidence: 99%

Pheromone-Regulated Expression of Sex Pheromone Plasmid pAD1-Encoded Aggregation Substance Depends on at Least Six Upstream Genes and a cis -Acting, Orientation-Dependent Factor

Muscholl-Silberhorn

2000

J Bacteriol

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Conjugative transfer of Enterococcus faecalis-specific sex pheromone plasmids relies on an adhesin, called aggregation substance, to confer a tight cell-to-cell contact between the mating partners. To analyze the dependence of pAD1-encoded aggregation substance, Asa1, on pheromone induction, a variety of upstream fragments were fused to an ␣-amylase reporter gene, amyL, by use of a novel promoter probe vector, pAMYem1. For pheromone-regulated ␣-amylase activity, a total of at least six genes, traB, traC, traA, traE1, orfY, and orf1, are required: TraB efficiently represses asa1 (by a mechanism unrelated to its presumptive function in pheromone shutdown, since a complete shutdown is observed exclusively in the presence of traC); only traC can relieve traB-mediated repression in a pheromone-dependent manner. In addition to traB, traA is required but not sufficient for negative control. Mutational inactivation of traE1, orfY, or orf1, respectively, results in a total loss of ␣-amylase activity for constructs normally mediating constitutive expression. Inversion of a fragment covering traA, P 0 , and traE1 without disrupting any gene or control element switches off amyL or asa1 expression, indicating the involvement of a cis-acting, orientation-dependent factor (as had been shown for plasmid pCF10). Unexpectedly, pAD1 represses all pAMY-em1 derivatives in trans, while its own pheromonedependent functions are unaffected. The discrepancy between the new data and those of former studies defining TraE1 as a trans-acting positive regulator is discussed.

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“…A transposon, Tn1545, identified on the chromosome of a strain of S. pneumoniae eventually proved to be a conjugative multiple-resistance element very similar to Tn916. 82 We were also discovering other elements similar to Tn916, namely Tn918 from E. faecalis RC73 and Tn919 in a strain of S. sanguis. 83,84 Tn916 and closely related elements were found to be particularly promiscuous, with evidence for dissemination throughout more than 23 different bacterial genera.…”

Section: The Tn916 Surprisementioning

confidence: 97%

Tales of conjugation and sex pheromones

Clewell¹

2011

Mobile Genetic Elements

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REVIEW REVIEW use of a technique that had recently been reported by Godson and Sinsheimer 6 that utilized a detergent mixture of Brij 58 (a neutral detergent) and deoxycholate for lysis of phageinfected E. coli. During a relatively low-speed centrifugation step, the vast majority of chromosomal DNA pelleted leaving the supernatant greatly enriched in plasmid DNA. Sucrose gradient analyses of these "cleared lysates" revealed a ColE1-protein complex sedimenting slightly faster (24S) than the 23S protein-free supercoiled DNA. Surprisingly, when the 24S complex was exposed to conditions expected to affect protein structure such as proteases, strong ionic detergents or heat, the 24S complex converted to a 17S relaxed (open circular) configuration. The relaxation event involved the introduction of a strand-specific nick in the supercoiled plasmid; we therefore called the 24S entity a "relaxation complex". 7,8 The percentage of plasmid DNA that was present in the complexed state varied from less than 30%, when glucose was in the growth medium, to more than 80% when glucose was absent.

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Tn1545: A conjugative shuttle transposon

Cited by 120 publications

References 36 publications

Natural transfer of conjugative transposon Tn916 between gram-positive and gram-negative bacteria

Natural transfer of conjugative transposon Tn916 between gram-positive and gram-negative bacteria

Pheromone-Regulated Expression of Sex Pheromone Plasmid pAD1-Encoded Aggregation Substance Depends on at Least Six Upstream Genes and a cis -Acting, Orientation-Dependent Factor

Tales of conjugation and sex pheromones

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