VirE1 protein mediates export of the single-stranded DNA-binding protein VirE2 from Agrobacterium tumefaciens into plant cells

Sundberg, Christopher; Meek, Laura; Carroll, Kate S.; Das, Anath Bandhu; Ream, Walt

doi:10.1128/jb.178.4.1207-1212.1996

Cited by 101 publications

(96 citation statements)

References 82 publications

(81 reference statements)

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Alternatively, it has been proposed that VirE2 and the VirD2:T-strand are exported independently from the bacterium and formation of the Tcomplex is completed in the plant cell cytoplasm (Binns et al, 1995;Gelvin, 1998;Lee et al, 1999;Sundberg et al, 1996). That VirE1 physically interacts with VirE2 suggests the binding of VirE2 to the T-strand is regulated in vivo but does not resolve the question of where or when this occurs (Deng et al, 1999;Sundberg and Ream, 1999;Sundberg et al, 1996). In either case, once bound to the T-strand, VirE2 provides protection from nucleolytic degradation.…”

Section: Ssdna Binding Proteins (Table 1 Item 9)mentioning

confidence: 99%

The transfer of DNA from Agrobacterium tumefaciens into plants: a feast of fundamental insights

et al. 2000

View full text Add to dashboard Cite

This review is dedicated to Jeff Schell, one of the founders of modern`Agrobiology', the genetic and molecular dissection of crown gall disease. Together with notable scientists at the University of Gent, Belgium, Jeff spearheaded the discovery of the Ti-plasmid. The elusive`tumor inducing principle' was uncloaked and provided impetus for an incredibly fruitful subsequent 25 years of analyses. Scientists all over the world were caught up in unraveling the underlying mechanisms of Agrobacterium-mediated gene transfer to plants, and along the way uncovered a movable feast of fundamental insights. Below we summarize a sampling of Agrobacterium's most recently recognized accomplishments.

show abstract

Section: Ssdna Binding Proteins (Table 1 Item 9)mentioning

confidence: 99%

The transfer of DNA from Agrobacterium tumefaciens into plants: a feast of fundamental insights

et al. 2000

View full text Add to dashboard Cite

show abstract

“…It was previously shown that VirE1 is essential for tumor formation (McBride and Knauf, 1988;Sundberg et al, 1996) and for a VirE2 helper strain to complement tumor formation of a virE2 mutant strain in extracellular complementation experiments. We confirmed loss of virulence of LBA2570 in tumor assays on N. glauca plants (Fig.…”

Section: Construction Of An a Tumefaciens Vire1 Deletion Strainmentioning

confidence: 99%

Recognition of the Agrobacterium tumefaciens VirE2 Translocation Signal by the VirB/D4 Transport System Does Not Require VirE1

et al. 2003

View full text Add to dashboard Cite

Agrobacterium tumefaciens uses a type IV secretion system to deliver a nucleoprotein complex and effector proteins directly into plant cells. The single-stranded DNA-binding protein VirE2, the F-box protein VirF and VirE3 are delivered into host cells via this VirB/D4 encoded translocation system. VirE1 functions as a chaperone of VirE2 by regulating its efficient translation and preventing VirE2-VirE2 aggregation in the bacterial cell. We analyzed whether the VirE1 chaperone is also essential for transport recognition of VirE2 by the VirB/D4 encoded type IV secretion system. In addition, we assayed whether translocation of VirF and VirE3, which also forms part of the virE operon, is affected by the absence of VirE1. We employed the earlier developed CRAFT (Cre recombinase Reporter Assay For Translocation) assay to detect transfer of Cre::Vir fusion proteins from A. tumefaciens into plants, monitored by stable reconstitution of a kanamycin resistance marker, and into yeast, screened by loss of the URA3 gene. We show that the C-terminal 50 amino acids of VirE2 and VirE3 are sufficient to mediate Cre translocation into host cells, confirming earlier indications of a C-terminal transport signal. This transfer was independent of the presence or absence of VirE1. Besides, the translocation efficiency of VirF is not altered in a virE1 mutant. The results unambiguously show that the VirE1 chaperone is not essential for the recognition of the VirE2 transport signal by the transport system and the subsequent translocation across the bacterial envelope into host cells.Agrobacterium tumefaciens causes crown gall disease on a wide range of plants by genetic transformation of host cells with a piece of its oncogenic plasmidborne transfer (T)-DNA (for most recent review, see Gelvin, 2003). The expression of the genes located on the T-DNA, which contain plant transcription and translation signals, results in overproduction of the plant hormones auxin and cytokinin and hence increased cell division and the tumor phenotype. A set of accessory virulence or effector proteins (encoded by the vir region on the tumor inducing [Ti] plasmid) is also transported into the transformed cells to confer full virulence. The host range is not confined to the plant kingdom, because A. tumefaciens can also transform yeast (Bundock et al., 1995), fungi (de Groot et al., 1998), and mammalian cells (Kunik et al., 2000).The translocated proteins of A. tumefaciens described to date include VirD2, VirE2, VirE3, and VirF. In the bacterium, VirD2 introduces a nick at the border sequences surrounding the T-DNA and by replacement synthesis a single-stranded (ss) DNA copy of the bottom strand is released. VirD2 acts as a pilot protein as it remains covalently attached to the 5Ј end of the T-strand during transport of the T-DNA into the host cell nucleus (Ward and Barnes, 1988). The ssDNA-binding protein VirE2 binds cooperatively to the T-strand and thereby protects it from degradation in the host cell (Rossi et al., 1996). Both VirD2 and VirE2 contain nucl...

show abstract

“…We next determined if VirE1, a molecular chaperone for VirE2 (23,39), is required for secretion of VirE2. A6007 (ptac-virE2::phoA) was assayed for phoA activity under noninducing conditions.…”

Section: Vire2 and Vird2mentioning

confidence: 99%

Transferred DNA (T-DNA)-associated proteins of Agrobacterium tumefaciens are exported independently of virB

Chen

Nester

2000

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

View full text Add to dashboard Cite

The transfer of T-DNA from Agrobacterium to plant cells is mediated by a system which involves the virB operon of the Ti plasmid. We report that VirE2 and VirD2, two T-DNA-associated proteins, as well as VirF, a protein known to be secreted into plant cells, are present in the periplasm and supernatant fractions of growing cells of Agrobacterium as are VirJ and ChvE, two known periplasmic proteins. Two cytoplasmic proteins, Ros and chloramphenicol acetyl transferase, and a VirE2::green fluorescent protein construct were not detected in the above fraction. Export of VirE2 into the culture supernatant did not require any Ti plasmid genes, except for VirE1, a specific chaperone for VirE2. The levels of the VirE2 and VirD2 proteins in the supernatant increased significantly when cells were grown at 19°C as compared with 28°C. When Agrobacterium expressed the oncogenic suppressive activity protein (Osa), VirE2 and VirF proteins could not be detected in the supernatant or the periplasm and the level of VirD2 was greatly reduced. However, oncogenic suppressive activity protein did not block the accumulation of VirJ and ChvE in the periplasm. Our data suggest that VirD2, VirE2, and VirF are transported across the cytoplasmic membrane by a specific pathway, independent of virB. Thus, transfer of the T-complex of Agrobacterium may take place in two steps, the first mediated by an unidentified pathway and the second by the virB system. virulence protein export ͉ secretion system

show abstract

VirE1 protein mediates export of the single-stranded DNA-binding protein VirE2 from Agrobacterium tumefaciens into plant cells

Cited by 101 publications

References 82 publications

The transfer of DNA from Agrobacterium tumefaciens into plants: a feast of fundamental insights

The transfer of DNA from Agrobacterium tumefaciens into plants: a feast of fundamental insights

Recognition of the Agrobacterium tumefaciens VirE2 Translocation Signal by the VirB/D4 Transport System Does Not Require VirE1

Transferred DNA (T-DNA)-associated proteins of Agrobacterium tumefaciens are exported independently of virB

Contact Info

Product

Resources

About