Conjugal Transfer of Agrobacterium Plasmids

Farrand, Stephen K.

doi:10.1007/978-1-4757-9357-4_10

Cited by 41 publications

(30 citation statements)

References 109 publications

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“…This DNA originates from a megaplasmid called the tumor-inducing (Ti) plasmid. In addition to mediating interkingdom DNA transfer, Ti plasmids are capable of conjugal DNA transfer between agrobacteria (10). Genes required for conjugation (tra genes) are positively regulated by the TraR protein, which is activated by the pheromone N-3-oxooctanoyl-L-homoserine lactone, sometimes referred to as Agrobacterium autoinducer, or AAI (4,7).…”

mentioning

confidence: 99%

Autoinducer binding by the quorum-sensing regulator TraR increases affinity for target promoters in vitro and decreases TraR turnover rates in whole cells

Zhu

Winans

1999

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

245

310

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TraR is an Agrobacterium transcriptional regulator whose activity requires the pheromone N-3-oxooctanoyl-L-homoserine lactone. TraR was purified as a complex with the pheromone and contained one pheromone molecule per protein monomer. TraR-pheromone complexes bound to a single DNA site and activated two promoters that flank this site. Promoter expression was elevated 30-fold by using a supercoiled template. Pheromone binding increased the affinity of TraR for this binding site. Pheromone also increased TraR abundance in vivo by causing a 20-fold decrease in TraR turnover rates.

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mentioning

confidence: 99%

Autoinducer binding by the quorum-sensing regulator TraR increases affinity for target promoters in vitro and decreases TraR turnover rates in whole cells

Zhu

Winans

1999

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

245

310

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“…Plasmids, extrachromosomal DNA molecules that replicate autonomously, contribute to this plasticity by mediating lateral gene transfer among bacterial species and genera (15,17,21,40,57,59,65) and even between kingdoms (19,24). In addition to their role in lateral gene transfer, plasmids also function in gene amplification and overexpression (46,47).…”

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Vertical Transmission of Biosynthetic Plasmids in Aphid Endosymbionts ( Buchnera )

Wernegreen

Moran

2001

J Bacteriol

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This study tested for horizontal transfer of plasmids among Buchnera aphidicola strains associated with ecologically and phylogenetically related aphid hosts (Uroleucon species). Phylogenetic congruence of Buchnera plasmid (trpEG and leuABC) and chromosomal (dnaN and trpB) genes supports strictly vertical long-term transmission of plasmids, which persist due to their contributions to host nutrition rather than capacity for infectious transfer. Synonymous divergences indicate elevated mutation on plasmids relative to chromosomal genes.

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“…Subsequent integration of the transferred DNA (T-DNA) into the plant cell nuclear genome and expression of gene sets encoded on this DNA fragment result in the conversion of the plant cells to crown gall tumor cells. The second system is responsible for the transmission of the entire Ti plasmid from a donor to a suitable bacterial recipient (13). Both conjugation systems are strongly regulated.…”

mentioning

confidence: 99%

“…Expression of the vir genes requires specific factors produced by wounded plant cells, as well as certain environmental conditions (5,24). Similarly, conjugal transfer occurs only when the bacteria sense the presence of specific metabolites, called opines, produced by the crown gall tumors (13). In addition, expression of genes involved in conjugal transfer is regulated by an autoinducerdependent quorum-sensing system (17,41).…”

mentioning

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Ti plasmid conjugation is independent of vir: reconstitution of the tra functions from pTiC58 as a binary system

Cook

Ruchaud

et al. 1997

J Bacteriol

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Two regions of the nopaline-type Ti plasmid pTiC58 are important for conjugal transfer of this element to recipient bacteria. These two regions were cloned into two independent replicons to produce a binary transfer system. For one region, oriT/tra, we constructed two derivatives, pFRtra and pDCtra-5. Each contains the oriT site and the two flanking, divergently transcribed tra operons that encode the DNA processing functions associated with the relaxosome. These two plasmids also carry traR, which encodes the transcriptional activator necessary for expression of transfer genes. The two plasmids differ by the amounts of traB sequence or sequence downstream of traG present in the construct. The second replicon, pPLE2, carries the traI/trb region. The traI gene confers production of the Agrobacterium tumefaciens N-acyl homoserine lactone autoinducer, while the remaining genes in the trb operon encode components of the mating bridge. Donors harboring the two plasmids mobilized the transfer of the plasmid carrying the oriT/tra region to an A. tumefaciens recipient at frequencies similar to that at which the intact Ti plasmid transferred. Plasmid pFRtra, which encodes most of traB, was mobilized at a frequency almost 10-fold higher than was pDCtra-5, which lacks most of the gene. A. tumefaciens donors also mobilized pFRtra to Escherichia coli and Pseudomonas fluorescens recipients at frequencies similar to those observed with A. tumefaciens recipients. Rhizobium meliloti harboring the binary system also transferred the oriT/tra component to these recipients. However, E. coli or P. fluorescens donors harboring the binary system did not transfer pFRtra to any of the recipients. Furthermore, while the A. tumefaciens and R. meliloti donors produced high levels of the autoinducer, the P. fluorescens and E. coli donors produced only trace amounts of this signal molecule. These results indicate that the tra system of pTiC58 is fully contained within the characterized tra and trb regions of the Ti plasmid, that conjugation does not require functions encoded by the vir system for maximal activity, and that while the Ti plasmid tra system recognizes diverse gram-negative bacteria as recipients, of the hosts tested, it functions only in members of the family Rhizobiaceae.

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Conjugal Transfer of Agrobacterium Plasmids

Cited by 41 publications

References 109 publications

Autoinducer binding by the quorum-sensing regulator TraR increases affinity for target promoters in vitro and decreases TraR turnover rates in whole cells

Autoinducer binding by the quorum-sensing regulator TraR increases affinity for target promoters in vitro and decreases TraR turnover rates in whole cells

Vertical Transmission of Biosynthetic Plasmids in Aphid Endosymbionts ( Buchnera )

Ti plasmid conjugation is independent of vir: reconstitution of the tra functions from pTiC58 as a binary system

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