<i>Agrobacterium tumefaciens</i> oncogenic suppressors inhibit T‐DNA and VirE2 protein substrate binding to the VirD4 coupling protein

Cascales, Éric; Atmakuri, Krishnamohan; Liu, Zhenying; Binns, Andrew N.; Christie, Peter J.

doi:10.1111/j.1365-2958.2005.04852.x

Cited by 33 publications

(22 citation statements)

References 75 publications

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“…4 and 6). This is consistent with the observations that RSF1010 can be transferred by the VirB/D4 T4SS (30, 31), and its transfer intermediate inhibits the binding of T-DNA to the VirD4 receptor (33). It appeared that T-DNA and RSF1010 transfer systems are related.…”

Section: Vbp1 Interacts With a Plasmid Conjugativesupporting

confidence: 80%

Recruitment of conjugative DNA transfer substrate to Agrobacterium type IV secretion apparatus

Guo

Jin

Sun

et al. 2007

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

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Bacterial type IV secretion system (T4SS) belongs to a growing class of evolutionarily conserved transporters that translocate DNA and proteins into a wide variety of organisms including bacterial and eukaryotic cells. Archetypal is the Agrobacterium tumefaciens VirB/D4 T4SS that transfers oncogenic T-DNA to various eukaryotic cells, which is transferred as a nucleoprotein T-complex with VirD2 as the pilot protein. As a derivative of plasmid conjugation systems, the VirB/D4 T4SS can also transfer certain mobilizable plasmids and bacterial proteins like VirE2 and VirF, although it is unknown how the membrane-bound T4SS recruits different transfer substrates. Here, we show that a cytoplasmic VirD2-binding protein (VBP) is involved in the recruitment of the T-complex to the energizing components of the T4SS, including VirD4, VirB4, and VirB11. VBP is also important for the recruitment of a conjugative plasmid to a different transfer system independent of VirB/D4. These data indicate that VBP functions as a previously unrecognized recruiting protein that helps couple nucleoprotein substrates to the appropriate transport sites for conjugative DNA transfers. VBP has three functionally redundant homologs, and similar homologs can be found in different bacterial genomes, suggesting a previously uncharacterized class of proteins involved in conjugative DNA transfers.bacterial type IV secretion system ͉ T-DNA ͉ virulence

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Section: Vbp1 Interacts With a Plasmid Conjugativesupporting

confidence: 80%

Recruitment of conjugative DNA transfer substrate to Agrobacterium type IV secretion apparatus

Guo

Jin

Sun

et al. 2007

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

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“…Our model conjugation system was that encoded by plasmid pKM101, which to date has only been shown to transfer pKM101 in E. coli and related enterobacterial species. The pKM101-encoded TraJ T4CP was swapped with A. tumefaciens VirD4 (here called VirD4 At ), a versatile receptor that recruits and mediates transfer of oncogenic T-DNA, plasmid pML122 (an RSF1010 derivative), and effector proteins through the VirB channel (15,30,41). We also replaced TraJ pKM101 with VirD4 homologs from the obligate intracellular species A. phagocytophilum and W. pipientis (Fig.…”

Section: Methodsmentioning

confidence: 99%

Chimeric Coupling Proteins Mediate Transfer of Heterologous Type IV Effectors through the Escherichia coli pKM101-Encoded Conjugation Machine

Whitaker¹,

Berry²,

Rosenthal³

et al. 2016

J Bacteriol

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Bacterial type IV secretion systems (T4SSs) are composed of two major subfamilies, conjugation machines dedicated to DNA transfer and effector translocators for protein transfer. We show here that the Escherichia coli pKM101-encoded conjugation system, coupled with chimeric substrate receptors, can be repurposed for transfer of heterologous effector proteins. The chimeric receptors were composed of the N-terminal transmembrane domain of pKM101-encoded TraJ fused to soluble domains of VirD4 homologs functioning in Agrobacterium tumefaciens, Anaplasma phagocytophilum, or Wolbachia pipientis. A chimeric receptor assembled from A. tumefaciens VirD4 (VirD4 At ) mediated transfer of a MOBQ plasmid (pML122) and A. tumefaciens effector proteins (VirE2, VirE3, and VirF) through the pKM101 transfer channel. Equivalent chimeric receptors assembled from the rickettsial VirD4 homologs similarly supported the transfer of known or candidate effectors from rickettsial species. These findings establish a proof of principle for use of the dedicated pKM101 conjugation channel, coupled with chimeric substrate receptors, to screen for translocation competency of protein effectors from recalcitrant species. Many T4SS receptors carry sequence-variable C-terminal domains (CTDs) with unknown function. While VirD4 At and the TraJ/VirD4 At chimera with their CTDs deleted supported pML122 transfer at wild-type levels, ⌬CTD variants supported transfer of protein substrates at strongly diminished or elevated levels. We were unable to detect binding of VirD4 At 's CTD to the VirE2 effector, although other VirD4 At domains bound this substrate in vitro. We propose that CTDs evolved to govern the dynamics of substrate presentation to the T4SS either through transient substrate contacts or by controlling substrate access to other receptor domains. IMPORTANCEBacterial type IV secretion systems (T4SSs) display striking versatility in their capacity to translocate DNA and protein substrates to prokaryotic and eukaryotic target cells. A hexameric ATPase, the type IV coupling protein (T4CP), functions as a substrate receptor for nearly all T4SSs. Here, we report that chimeric T4CPs mediate transfer of effector proteins through the Escherichia coli pKM101-encoded conjugation system. Studies with these repurposed conjugation systems established a role for acidic C-terminal domains of T4CPs in regulating substrate translocation. Our findings advance a mechanistic understanding of T4CP receptor activity and, further, support a model in which T4SS channels function as passive conduits for any DNA or protein substrates that successfully engage with and pass through the T4CP specificity checkpoint.T he type IV secretion systems (T4SSs) display striking versatility among the known bacterial translocation systems in their capacity to translocate DNA and protein substrates to bacterial or eukaryotic target cells (1, 2). Members of one major T4SS subfamily, the conjugation machines, mediate transfer of mobile DNA elements and are responsible for widespr...

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“…1). A gene designated bcvirD4 showed homology to other T4SS coupling proteins, which serve as active motors necessary for substrate transfer through the T4SS Christie et al, 2005). To investigate the role of the chromosome-encoded bc-VirB/D4 system in B. cenocepacia K56-2, a deletion in bcvirD4 with insertion of the Tp r cassette was constructed.…”

Section: Resultsmentioning

confidence: 99%

“…T4SSs are used by bacteria to translocate DNA and protein macromolecules to a diverse range of bacterial and eukaryotic cells (Christie et al, 2005). T4SSs also mediate horizontal gene transfer, and contribute to genome plasticity and the evolution of pathogens through dissemination of antibiotic resistance and virulence genes (Juhas et al, 2007 (Schröder & Lanka, 2005).…”

Section: Discussionmentioning

confidence: 99%

“…Agrobacterium tumefaciens has three T4SSs: the virB/D4 system encoded by the Ti plasmid is the paradigm of T4SS and transfers T-DNA into plant cells, resulting in the development of crown-gall tumours (Christie et al, 2005); the trb system, required for the conjugal transfer of the Ti plasmid between cells of A. tumefaciens (Li et al, 1998(Li et al, , 1999; and the avhB system, which mediates the conjugal transfer of the pAtC58 cryptic plasmid (Chen et al, 2002). AvhB also promotes the conjugal transfer of the IncQ plasmid RSF1010.…”

Section: Introductionmentioning

confidence: 99%

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Two type IV secretion systems with different functions in Burkholderia cenocepacia K56-2

2009

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Bacterial type IV secretion systems (T4SS) perform two fundamental functions related to pathogenesis: the delivery of effector molecules to eukaryotic target cells, and genetic exchange. Two T4SSs have been identified in Burkholderia cenocepacia K56-2, a representative of the ET12 lineage of the B. cepacia complex (Bcc). The plant tissue watersoaking (Ptw) T4SS encoded on a resident 92 kb plasmid is a chimera composed of VirB/D4 and F-specific subunits, and is responsible for the translocation of effector(s) that have been linked to the Ptw phenotype. The bc-VirB/D4 system located on chromosome II displays homology to the VirB/D4 T4SS of Agrobacterium tumefaciens. In contrast to the Ptw T4SS, the bc-VirB/D4 T4SS was found to be dispensable for Ptw effector(s) secretion, but was found to be involved in plasmid mobilization. The fertility inhibitor Osa did not affect the secretion of Ptw effector(s) via the Ptw system, but did disrupt the mobilization of a RSF1010 derivative plasmid.

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Agrobacterium tumefaciens oncogenic suppressors inhibit T‐DNA and VirE2 protein substrate binding to the VirD4 coupling protein

Abstract: Summary Agrobacterium tumefaciens uses a type IV secretion (T4S) system composed of VirB proteins and VirD4 to deliver oncogenic DNA (T-DNA

Cited by 33 publications

References 75 publications

Recruitment of conjugative DNA transfer substrate to Agrobacterium type IV secretion apparatus

Recruitment of conjugative DNA transfer substrate to Agrobacterium type IV secretion apparatus

Chimeric Coupling Proteins Mediate Transfer of Heterologous Type IV Effectors through the Escherichia coli pKM101-Encoded Conjugation Machine

Two type IV secretion systems with different functions in Burkholderia cenocepacia K56-2

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