Genetic and functional characterization of a yet-unclassified rhizobial Dtr (DNA-transfer-and-replication) region from a ubiquitous plasmid conjugal system present in Sinorhizobium meliloti, in Sinorhizobium medicae, and in other nonrhizobial Gram-negative bacteria

Giusti, Maria De; Pistorio, Mariano; Lozano, Mauricio Javier; Tejerizo, Gonzalo Arturo Torres; Salas, María Eugenia; Martini, María Carla; López, José Luis; Draghi, Walter Omar; Papa, María Florencia Del; Pérez-Mendoza, Daniel; Sanjuán, Juan; Lagares, Antonio

doi:10.1016/j.plasmid.2011.12.010

Cited by 25 publications

(31 citation statements)

References 67 publications

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“…1B). However, it is noticeable from the relaxase phylogenetic trees, both as presented by Giusti et al (19) and in this article, that the pRleVF39b relaxase is clearly on a different branch from the rest of the type IV relaxases. The organization of the pRleVF39b genes in the vicinity of relaxase is also different from those in other type IV systems.…”

Section: Discussionsupporting

confidence: 45%

“…In a recent study, the relaxase from pSmeLPU88b of Ensifer meliloti LPU88 was characterized by Giusti et al (19). Phylogenetic analyses showed that this relaxase together with relaxases from pSmed03 of S. medicae WSM419, pAtS4a from Agrobacterium vitis S4, plasmid 1 of Chelativorans sp.…”

Section: Discussionmentioning

confidence: 99%

“…Recently, the relaxase of pRleVF39b has been shown to belong to the MOB P0 type relaxase group (19). However, the pRleVF39b conjugation system differs from the MOB P0 conjugation systems in several ways.…”

Section: ϫ5mentioning

confidence: 99%

“…None of the type III plasmids were self-transmissible due to the lack of an Mpf component. In a recent study, the relaxase on pSmeLPU88b of Ensifer meliloti LPU88 has been characterized (19). Phylogenetic analyses showed that pSmeLPU88b relaxase together with relaxases from pSmed03 of Ensifer medicae WSM419, pSmeGR4a of E. meliloti GR4, pSmeSM11c from E. meliloti SM11, and pRleVF39b from R. leguminosarum bv.…”

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Genetic Characterization of a Novel Rhizobial Plasmid Conjugation System in Rhizobium leguminosarum bv. viciae Strain VF39SM

2013

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Rhizobium leguminosarum strain VF39SM contains two plasmids that have previously been shown to be self-transmissible by conjugation. One of these plasmids, pRleVF39b, is shown in this study to carry a set of plasmid transfer genes that differs significantly from conjugation systems previously studied in the rhizobia but is similar to an uncharacterized set of genes found in R. leguminosarum bv. trifolii strain WSM2304. The entire sequence of the transfer region on pRleVF39b was determined as part of a genome sequencing project, and the roles of the various genes were examined by mutagenesis. The transfer region contains a complete set of mating pair formation (Mpf) genes, a traG gene, and a relaxase gene, traA, all of which appear to be necessary for plasmid transfer. Experimental evidence suggested the presence of two putative origins of transfer within the gene cluster. A regulatory gene, trbR, was identified in the region between traA and traG and was mutated. TrbR was shown to function as a repressor of both trb gene expression and plasmid transfer. Rhizobia are agriculturally important bacteria that are capable of forming nitrogen-fixing nodules on the roots of legumes, such as peas, lentils, and beans. In fast-growing rhizobia, such as the genera Rhizobium and Ensifer (Sinorhizobium), the genes required for establishment of this symbiosis (nod, nif, and fix genes) are usually located on one of the large plasmids, known as pSyms. In addition, other large rhizobial plasmids carry genes beneficial for bacterial fitness and competitiveness in the rhizosphere, such as genes encoding bacteriocin production, lipopolysaccharide production, exopolysaccharide production, utilization of different carbon sources, and synthesis of specific vitamins (1-9).Although plasmid conjugation has not been shown to enhance bacterial competitiveness directly, it is one of the most important methods for bacteria to acquire genetic information and adapt to changing environmental conditions. There is considerable evidence for rhizobial plasmid transfer both under laboratory conditions (10-13), and in natural environments (14-16). In addition, genome sequences of many rhizobial strains and rhizobial plasmids have revealed potential conjugation genes encoding DNA transfer and replication (Dtr) components and mating pair formation (Mpf) components, as well as putative origins of transfer (oriT).Two types of rhizobial conjugation systems have been characterized, including the quorum sensing (QS)-regulated conjugation system (type I) and the RctA-repressed conjugation system (type II). In a recent review, we demonstrated that these two conjugation systems are phylogenetically separate, consistent with their characterized transfer regulation (8). In addition, we proposed the presence of the type III conjugation system on plasmids pRL10JI, pRL11JI, and pRL12JI of Rhizobium leguminosarum bv. viciae 3841 (17), and pRleVF39d, pRleVF39e, pRleVF39f of R. leguminosarum bv. viciae VF39SM (18) based on sequence information (8). None of the type III...

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Section: Discussionsupporting

confidence: 45%

Section: Discussionmentioning

confidence: 99%

Section: ϫ5mentioning

confidence: 99%

mentioning

confidence: 99%

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Genetic Characterization of a Novel Rhizobial Plasmid Conjugation System in Rhizobium leguminosarum bv. viciae Strain VF39SM

2013

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“…The types I and II Dtr systems are found to be encoded by autotransferable plasmids, and the type III by mobilizable ones [55]. It has been proposed that class I Dtr systems such as the one encoded by the pTiC58 tra genes, are regulated by QS while class II Dtr sytems, including the one encoded by the pAtC58 tra genes, are regulated by an RctA repressor associated with an RctB anti-activator [55, 56]. Interestingly, the organization of the four tra genes of pAtP4 did not reveal the presence of traF and traB orthologs downstream of traA, a key feature of type I Dtr systems.…”

Section: Discussionmentioning

confidence: 99%

Transcriptome analysis revealed that a quorum sensing system regulates the transfer of the pAt megaplasmid in Agrobacterium tumefaciens

et al. 2016

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BackgroundAgrobacterium tumefaciens strain P4 is atypical, as the strain is not pathogenic and produces a for this species unusual quorum sensing signal, identified as N-(3-hydroxy-octanoyl)-homoserine lactone (3OH,C8-HSL).ResultsBy sequence analysis and cloning, a functional luxI-like gene, named cinI, has been identified on the At plasmid of A. tumefaciens strain P4. Insertion mutagenesis in the cinI gene and transcriptome analyses permitted the identification of 32 cinI-regulated genes in this strain, most of them encoding proteins responsible for the conjugative transfer of pAtP4. Among these genes were the avhB genes that encode a type 4 secretion system (T4SS) involved in the formation of the conjugation apparatus, the tra genes that encode the DNA transfer and replication (Dtr) machinery and cinI and two luxR orthologs. These last two genes, cinR and cinX, exhibit an unusual organization, with the cinI gene surrounded by the two luxR orthologs. Conjugation experiments confirmed that the conjugative transfer of pAtP4 is regulated by 3OH,C8-HSL. Root colonization experiments indicated that the quorum sensing regulation of the conjugation of the pAtP4 does not confer a gain or a loss of fitness to the bacterial host in the tomato plant rhizosphere.ConclusionThis work is the first identification of the occurrence of a quorum sensing regulation of the pAt conjugation phenomenon in Agrobacterium.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-016-3007-5) contains supplementary material, which is available to authorized users.

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Boundaries for Conjugative Transfer of Rhizobial Plasmids: Restraining and Releasing Factors

Brom

Pistorio

Romero

et al. 2014

Plasticity in Plant-Growth-Promoting and Phytopathogenic Bacteria

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Genetic and functional characterization of a yet-unclassified rhizobial Dtr (DNA-transfer-and-replication) region from a ubiquitous plasmid conjugal system present in Sinorhizobium meliloti, in Sinorhizobium medicae, and in other nonrhizobial Gram-negative bacteria

Cited by 25 publications

References 67 publications

Genetic Characterization of a Novel Rhizobial Plasmid Conjugation System in Rhizobium leguminosarum bv. viciae Strain VF39SM

Genetic Characterization of a Novel Rhizobial Plasmid Conjugation System in Rhizobium leguminosarum bv. viciae Strain VF39SM

Transcriptome analysis revealed that a quorum sensing system regulates the transfer of the pAt megaplasmid in Agrobacterium tumefaciens

Boundaries for Conjugative Transfer of Rhizobial Plasmids: Restraining and Releasing Factors

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