Agrobacterium tumefaciens as an agent of disease

Escobar, Matthew A.; Dandekar, Abhaya M.

doi:10.1016/s1360-1385(03)00162-6

Cited by 274 publications

(188 citation statements)

References 66 publications

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“…Early biochemical evidence suggested that these are probably tetramers (21), while recent evidence points to trimers. 2 In the presence of ssDNA, ring-like objects also appeared on the grids. They were often found next to the ends of helical filaments, where the circular DNA had broken to linear segments (Fig.…”

Section: Resultsmentioning

confidence: 99%

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Three-dimensional Reconstruction of Agrobacterium VirE2 Protein with Single-stranded DNA

Abu‐Arish

Frenkiel-Krispin

Fricke

et al. 2004

Journal of Biological Chemistry

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Agrobacterium tumefaciens infects plant cells by a unique mechanism involving an interkingdom genetic transfer. A single-stranded DNA substrate is transported across the two cell walls along with the bacterial virulence proteins VirD2 and VirE2. A single VirD2 molecule covalently binds to the 5 -end of the singlestranded DNA, while the VirE2 protein binds stoichiometrically along the length of the DNA, without sequence specificity. An earlier transmission/scanning transmission electron microscopy study indicated a solenoidal ("telephone coil") organization of the VirE2-DNA complex. Here we report a three-dimensional reconstruction of this complex using electron microscopy and single-particle image-processing methods. We find a hollow helical structure of 15.7-nm outer diameter, with a helical rise of 51.5 nm and 4.25 VirE2 proteins/turn. The inner face of the protein units contains a continuous wall and an inward protruding shelf. These structures appear to accommodate the DNA binding. Such a quaternary arrangement naturally sequesters the DNA from cytoplasmic nucleases and suggests a mechanism for its nuclear import by decoration with host cell factors. Coexisting with the helices, we also found VirE2 tetrameric ring structures. A two-dimensional average of the latter confirms the major features of the threedimensional reconstruction.

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Section: Resultsmentioning

confidence: 99%

“…Agrobacterium tumefaciens is the causative agent of the crown gall disease in many plant species (1,2). To attack its host, Agrobacterium employs a unique and complex transformation process.…”

mentioning

confidence: 99%

Three-dimensional Reconstruction of Agrobacterium VirE2 Protein with Single-stranded DNA

Abu‐Arish

Frenkiel-Krispin

Fricke

et al. 2004

Journal of Biological Chemistry

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“…A. tumefaciens is best known for its ability to cause crown gall neoplasia on plants. This occurs via cross-kingdom horizontal gene transfer (HGT) of a segment of transferred DNA called "T-DNA," to plant cells, where it is subsequently imported into the nucleus and integrated into the genome (17). Genes expressed from T-DNA in the plant cause a hormonal imbalance, uncontrolled cell proliferation, and gall formation.…”

mentioning

confidence: 99%

Antiparallel and Interlinked Control of Cellular Iron Levels by the Irr and RirA Regulators of Agrobacterium tumefaciens

Hibbing

Fuqua

2011

J Bacteriol

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The plant pathogen Agrobacterium tumefaciens encodes predicted iron-responsive regulators, Irr and RirA, that function in several other bacteria to control the response to environmental iron levels. Deletion mutations of irr and rirA, alone and in combination, were evaluated for their impact on cellular iron response. Growth was severely diminished in the ⌬irr mutant under iron-limiting conditions, but reversed to wild-type levels in an ⌬irr ⌬rirA mutant. The level of uncomplexed iron in the ⌬irr mutant was decreased, whereas the ⌬rirA mutant exhibited elevated iron levels. Sensitivity of the ⌬irr and ⌬rirA mutants to iron-activated antimicrobial compounds generally reflected their uncomplexed-iron levels. Expression of genes that encode iron uptake systems was decreased in the ⌬irr mutant, whereas that of iron utilization genes was increased. Irr function required a trihistidine repeat likely to mediate interactions with heme. Iron uptake genes were derepressed in the ⌬rirA mutant. In the ⌬irr ⌬rirA mutant, iron uptake and utilization genes were derepressed, roughly combining the phenotypes of the single mutants. Siderophore production was elevated in the rirA mutant, but most strongly regulated by an RirA-controlled sigma factor. Expression of rirA itself was regulated by Irr, RirA, and iron availability, in contrast to irr expression, which was relatively stable in the different mutants. These studies suggest that in A. tumefaciens, the Irr protein is most active under low-iron conditions, inhibiting iron utilization and activating iron acquisition, while the RirA protein is active under high-iron conditions, repressing iron uptake.

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“…Such strains contain plasmids that carry genes required for plant pathogenicity, and the transfer of these plasmids between agrobacteria requires both an appropriate population density and the presence of a specialized carbon source (opines) (Fuqua & Winans, 1996;Piper et al, 1999). The DNA transferred to the plant includes genes for promoting cell proliferation and for synthesizing secondary metabolites called opines (Escobar & Dandekar, 2003). These plant-made opines are secreted from transformed plants and induce the expression of specialized uptake and catabolism genes in A. tumefaciens.…”

Section: Introductionmentioning

confidence: 99%

Quorum-sensing-regulated transcriptional initiation of plasmid transfer and replication genes in Rhizobium leguminosarum biovar viciae

et al. 2007

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Agrobacterium tumefaciens as an agent of disease

Cited by 274 publications

References 66 publications

Three-dimensional Reconstruction of Agrobacterium VirE2 Protein with Single-stranded DNA

Three-dimensional Reconstruction of Agrobacterium VirE2 Protein with Single-stranded DNA

Antiparallel and Interlinked Control of Cellular Iron Levels by the Irr and RirA Regulators of Agrobacterium tumefaciens

Quorum-sensing-regulated transcriptional initiation of plasmid transfer and replication genes in Rhizobium leguminosarum biovar viciae

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