Mobilization of “Nonmobilizable” Plasmids by the Aggregation-Mediated Conjugation System ofBacillus thuringiensis

Andrup, Lars; Jørgensen, Ole Steen; Wilcks, Andrea; Smidt, Lasse; Jensen, Gert B.

doi:10.1006/plas.1996.0035

Cited by 55 publications

(53 citation statements)

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“…The effect of time on plasmid transfer frequency was evaluated by varying the amount of time (6,24,48, and 72 h) that the donor and recipient strains were incubated together. At the end of each time period, plasmid transfer frequencies were calculated as described in Materials and Methods.…”

Section: Resultsmentioning

confidence: 99%

“…For example, pheromone-mediated conjugative plasmid transfer occurs in enterococci (9,12,21), wherein recipient cells excrete a pheromone that, when bound by donor cells, initiates a sequence of events resulting in aggregation of donor and recipient cells and the formation of a mating channel through which plasmid DNA is transferred to recipient cells (12). Aggregation-mediated transfer is documented in Bacillus thuringiensis and lactic acid bacteria (LAB) (5,6,45,55). In B. thuringiensis, two aggregation phenotypes (Agr ϩ and Agr Ϫ ) have been identified in donor and recipient cells, respectively, but their molecular basis is not understood (21).…”

Section: Discussionmentioning

confidence: 99%

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Conjugal Transfer of a Virulence Plasmid in the Opportunistic Intracellular Actinomycete Rhodococcus equi

et al. 2012

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Rhodococcus equi is a facultative intracellular, Gram-positive, soilborne actinomycete which can cause severe pyogranulomatous pneumonia with abscessation in young horses (foals) and in immunocompromised people, such as persons with AIDS. All strains of R. equi isolated from foals and approximately a third isolated from humans contain a large, ϳ81-kb plasmid which is essential for the intramacrophage growth of the organism and for virulence in foals and murine in vivo model systems. We found that the entire virulence plasmid could be transferred from plasmid-containing strains of R. equi (donor) to plasmid-free R. equi strains (recipient) at a high frequency and that plasmid transmission reestablished the capacity for intracellular growth in macrophages. Plasmid transfer required living cells and cell-to-cell contact and was unaffected by the presence of DNase, factors pointing to conjugation as the major means of genetic transfer. Deletion of a putative relaxase-encoding gene, traA, located in the proposed conjugative region of the plasmid, abolished plasmid transfer. Reversion of the traA mutation restored plasmid transmissibility. Finally, plasmid transmission to other Rhodococcus species and some additional related organisms was demonstrated. This is the first study showing a virulence plasmid transfer in R. equi, and it establishes a mechanism by which the virulence plasmid can move among bacteria in the soil.

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Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Conjugal Transfer of a Virulence Plasmid in the Opportunistic Intracellular Actinomycete Rhodococcus equi

et al. 2012

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“…It contains up to 10 plasmids. One of them, a 114-kb plasmid, carries the toxin genes, while the plasmid transfer factors are ascribed to the conjugative 200-kb plasmid pXO16 (5,87,104).…”

Section: Bacillus Thuringienis and In Lactic Acid Bacteriamentioning

confidence: 99%

“…israelensis is accompanied by non-pheromoneinduced and protease-sensitive coaggregation between donor and recipient cells (4 (104), and it is supposed that the pXO16-mediated B. thuringiensis subsp. israelensis plasmid transfer system mobilizes plasmids of distinct replication types independent of the presence of oriT and mob functions on the mobilized plasmids (5). The fact that all plasmids tested so far (theta-replicating plasmid pAM␤1; ori43-, ori44-, and ori60-containing plasmids; and Bacillus cereus plasmid pBC16) could be mobilized by the pXO16-encoded conjugation system suggests that pXO16 possesses an exceptional and, so far, unique system (5), whose molecular basis remains to be elucidated.…”

Section: Bacillus Thuringienis and In Lactic Acid Bacteriamentioning

confidence: 99%

Conjugative Plasmid Transfer in Gram-Positive Bacteria

Grohmann

Muth

Espinosa

2003

Microbiol Mol Biol Rev

504

447

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Conjugative transfer of bacterial plasmids is the most efficient way of horizontal gene spread, and it is therefore considered one of the major reasons for the increase in the number of bacteria exhibiting multiple-antibiotic resistance. Thus, conjugation and spread of antibiotic resistance represents a severe problem in antibiotic treatment, especially of immunosuppressed patients and in intensive care units. While conjugation in gram-negative bacteria has been studied in great detail over the last decades, the transfer mechanisms of antibiotic resistance plasmids in gram-positive bacteria remained obscure. In the last few years, the entire nucleotide sequences of several large conjugative plasmids from gram-positive bacteria have been determined. Sequence analyses and data bank comparisons of their putative transfer (tra) regions have revealed significant similarities to tra regions of plasmids from gram-negative bacteria with regard to the respective DNA relaxases and their targets, the origins of transfer (oriT), and putative nucleoside triphosphatases NTP-ases with homologies to type IV secretion systems. In contrast, a single gene encoding a septal DNA translocator protein is involved in plasmid transfer between micelle-forming streptomycetes. Based on these clues, we propose the existence of two fundamentally different plasmid-mediated conjugative mechanisms in gram-positive microorganisms, namely, the mechanism taking place in unicellular gram-positive bacteria, which is functionally similar to that in gram-negative bacteria, and a second type that occurs in multicellular gram-positive bacteria, which seems to be characterized by double-stranded DNA transfer

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“…Previous studies found that certain plasmids from Bacillus thuringiensis or B. subtilis could be mobilized in the absence of mobilization functions (2,3,38,45). For example, the conjugative transposon Tn916 can mobilize pC194 from B. subtilis to B. thuringiensis at a low frequency (38), even though pC194 is still described as not being mobilizable.…”

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confidence: 99%

The Bacillus subtilis Conjugative Transposon ICEBs1Mobilizes Plasmids Lacking Dedicated Mobilization Functions

2012

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Integrative and conjugative elements (ICEs, also known as conjugative transposons) are mobile elements that are found integrated in a host genome and can excise and transfer to recipient cells via conjugation. ICEs and conjugative plasmids are found in many bacteria and are important agents of horizontal gene transfer and microbial evolution. Conjugative elements are capable of self-transfer and also capable of mobilizing other DNA elements that are not able to self-transfer. Plasmids that can be mobilized by conjugative elements are generally thought to contain an origin of transfer ( oriT ), from which mobilization initiates, and to encode a mobilization protein (Mob, a relaxase) that nicks a site in oriT and covalently attaches to the DNA to be transferred. Plasmids that do not have both an oriT and a cognate mob are thought to be nonmobilizable. We found that Bacillus subtilis carrying the integrative and conjugative element ICE Bs1 can transfer three different plasmids to recipient bacteria at high frequencies. Strikingly, these plasmids do not have dedicated mobilization- oriT functions. Plasmid mobilization required conjugation proteins of ICE Bs1 , including the putative coupling protein. In contrast, plasmid mobilization did not require the ICE Bs1 conjugative relaxase or cotransfer of ICE Bs1 , indicating that the putative coupling protein likely interacts with the plasmid replicative relaxase and directly targets the plasmid DNA to the ICE Bs1 conjugation apparatus. These results blur the current categorization of mobilizable and nonmobilizable plasmids and indicate that conjugative elements play a role in horizontal gene transfer even more significant than previously recognized.

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Mobilization of “Nonmobilizable” Plasmids by the Aggregation-Mediated Conjugation System ofBacillus thuringiensis

Cited by 55 publications

References 0 publications

Conjugal Transfer of a Virulence Plasmid in the Opportunistic Intracellular Actinomycete Rhodococcus equi

Conjugal Transfer of a Virulence Plasmid in the Opportunistic Intracellular Actinomycete Rhodococcus equi

Conjugative Plasmid Transfer in Gram-Positive Bacteria

The Bacillus subtilis Conjugative Transposon ICEBs1Mobilizes Plasmids Lacking Dedicated Mobilization Functions

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