Retrotransfer or gene capture: a feature of conjugative plasmids, with ecological and evolutionary significance

Szpirer, C; Top, Eva; Couturier, Martine; Mergeay, M.

doi:10.1099/00221287-145-12-3321

Cited by 68 publications

(55 citation statements)

References 55 publications

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“…2). Plasmid poriT34bp was mobilized by the IncP plasmid pSL2T (47) in the presence of pBBR1CM, but no mobilization of poriT18bp was observed under these conditions. These results show that the transfer origin is contained in the 34-bp 5Ј part of the RSA region.…”

Section: Vol 183 2001mentioning

confidence: 99%

Mobilization Function of the pBHR1 Plasmid, a Derivative of the Broad-Host-Range Plasmid pBBR1

2001

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The pBHR1 plasmid is a derivative of the small (2.6-kb), mobilizable broad-host-range plasmid pBBR1, which was isolated from the gram-negative bacterium Bordetella bronchiseptica (R. Antoine and C. Locht, Mol. Microbiol. 6:1785-1799, 1992). Plasmid pBBR1 consists of two functional cassettes and presents sequence similarities with the transfer origins of several plasmids and mobilizable transposons from gram-positive bacteria. We show that the Mob protein specifically recognizes a 52-bp sequence which contains, in addition to the transfer origin, the promoter of the mob gene. We demonstrate that this gene is autoregulated. The binding of the Mob protein to the 52-bp sequence could thus allow the formation of a protein-DNA complex with a double function: relaxosome formation and mob gene regulation. We show that the Mob protein is a relaxase, and we located the nic site position in vitro. After sequence alignment, the position of the nic site of pBBR1 corresponds with those of the nick sites of the Bacteroides mobilizable transposon Tn4555 and the streptococcal plasmid pMV158. The oriT of the latter is characteristic of a family of mobilizable plasmids that are found in gram-positive bacteria and that replicate by the rolling-circle mechanism. Plasmid pBBR1 thus appears to be a new member of this group, even though it resides in gram-negative bacteria and does not replicate via a rolling-circle mechanism. In addition, we identified two amino acids of the Mob protein necessary for its activity, and we discuss their involvement in the mobilization mechanism.

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Section: Vol 183 2001mentioning

confidence: 99%

Mobilization Function of the pBHR1 Plasmid, a Derivative of the Broad-Host-Range Plasmid pBBR1

2001

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“…4B). This bidirectionality phenomenon is somehow similar to conjugative retrotransfer processes, where recipient cells can occasionally act as donor cells (37)(38)(39)(40). However, in contrast to classical conjugative retrotransfer, where gene flow from recipient to donor is the consequence of two sequential rounds of DNA transfer in which the recipient becomes a secondary donor after obtaining DNA from the primary donor (39), the cell-to-cell DNA transfer system of T. thermophilus could a priori permit simultaneous bidirectional DNA transfer, resembling a hermaphroditism-like trait.…”

Section: Figmentioning

confidence: 99%

Noncanonical Cell-to-Cell DNA Transfer in Thermus spp. Is Insensitive to Argonaute-Mediated Interference

et al. 2015

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bHorizontal gene transfer drives the rapid evolution of bacterial populations. Classical processes that promote the lateral flow of genetic information are conserved throughout the prokaryotic world. However, some species have nonconserved transfer mechanisms that are not well known. This is the case for the ancient extreme thermophile Thermus thermophilus. In this work, we show that T. thermophilus strains are capable of exchanging large DNA fragments by a novel mechanism that requires cell-tocell contacts and employs components of the natural transformation machinery. This process facilitates the bidirectional transfer of virtually any DNA locus but favors by 10-fold loci found in the megaplasmid over those in the chromosome. In contrast to naked DNA acquisition by transformation, the system does not activate the recently described DNA-DNA interference mechanism mediated by the prokaryotic Argonaute protein, thus allowing the organism to distinguish between DNA transferred from a mate and exogenous DNA acquired from unknown hosts. This Argonaute-mediated discrimination may be tentatively viewed as a strategy for safe sharing of potentially "useful" traits by the components of a given population of Thermus spp. without increasing the genome sizes of its individuals. L ateral gene flow is responsible for the enormous plasticity observed in prokaryotic genomes, which confers on these organisms the ability to adapt rapidly to environmental changes (1-5). Three conserved mechanisms are traditionally associated with lateral gene transfer (LGT) in prokaryotes: phage-mediated transduction, natural transformation, and conjugation. Besides, alternative DNA transfer systems based on nanotubes (6), membrane vesicles, and nanopods in Archaea (7-9), or on the so-called "gene transfer agents" (10), have been described as contributors to genetic exchange among prokaryotes. Among these processes, transformation and conjugation depend only on functions encoded by the bacterial cell. Transformation involves the uptake of naked DNA from the environment and relies entirely on the ability of a competent recipient cell to incorporate DNA. Conjugation, on the other hand, is traditionally seen as the unidirectional transfer of a plasmid DNA molecule from a donor to a recipient cell, where the proteins responsible for DNA transfer are provided exclusively by the donor cell (11).Conjugation differs from transformation not only in the imperative need for a mate for the transfer of DNA but also in the nature of the transferred DNA. While transformation can be envisioned as a mechanism that might have originally evolved in ancestral bacteria, such as Thermus spp., for the acquisition of DNA of any sort and origin as a nutrient, conjugation is more frequently associated with a gain of new capabilities from related species and commonly involves plasmids or megaplasmids that encode all the functions required for conjugation. In fact, transfer of chromosomal genes is apparently less common and in many cases requires the integration of a conjug...

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“…Indeed, the other related T4SSs found in firmicutes also seem to carry fewer genes than MPF F systems. On the other hand, MPF T systems include plasmids with a broad host range (140) and that are capable of retrotransfer (134). Thus, along with the capacity to mate in liquid medium, MPF F evolved toward a narrower host range.…”

Section: Coevolution Of Mobilization and Conjugationmentioning

confidence: 99%

Mobility of Plasmids

Smillie

Garcillán-Barcia

Francia

et al. 2010

Microbiol Mol Biol Rev

981

1,054

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International audiencePlasmids are key vectors of horizontal gene transfer and essential genetic engineering tools. They code for genes involved in many aspects of microbial biology, including detoxication, virulence, ecological interactions, and antibiotic resistance. While many studies have decorticated the mechanisms of mobility in model plasmids, the identification and characterization of plasmid mobility from genome data are unexplored. By reviewing the available data and literature, we established a computational protocol to identify and classify conjugation and mobilization genetic modules in 1,730 plasmids. This allowed the accurate classification of proteobacterial conjugative or mobilizable systems in a combination of four mating pair formation and six relaxase families. The available evidence suggests that half of the plasmids are nonmobilizable and that half of the remaining plasmids are conjugative. Some conjugative systems are much more abundant than others and preferably associated with some clades or plasmid sizes. Most very large plasmids are nonmobilizable, with evidence of ongoing domestication into secondary chromosomes. The evolution of conjugation elements shows ancient divergence between mobility systems, with relaxases and type IV coupling proteins (T4CPs) often following separate paths from type IV secretion systems. Phylogenetic patterns of mobility proteins are consistent with the phylogeny of the host prokaryotes, suggesting that plasmid mobility is in general circumscribed within large clades. Our survey suggests the existence of unsuspected new relaxases in archaea and new conjugation systems in cyanobacteria and actinobacteria. Few genes, e.g., T4CPs, relaxases, and VirB4, are at the core of plasmid conjugation, and together with accessory genes, they have evolved into specific systems adapted to specific physiological and ecological contexts

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Retrotransfer or gene capture: a feature of conjugative plasmids, with ecological and evolutionary significance

Cited by 68 publications

References 55 publications

Mobilization Function of the pBHR1 Plasmid, a Derivative of the Broad-Host-Range Plasmid pBBR1

Mobilization Function of the pBHR1 Plasmid, a Derivative of the Broad-Host-Range Plasmid pBBR1

Noncanonical Cell-to-Cell DNA Transfer in Thermus spp. Is Insensitive to Argonaute-Mediated Interference

Mobility of Plasmids

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