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Dickinson L, Yuan W, LeBlanc C, Thomson G, Wang S, Jacob Y. Regulation of gene editing using T-DNA concatenation. NATURE PLANTS 2023; 9:1398-1408. [PMID: 37653336 PMCID: PMC11193869 DOI: 10.1038/s41477-023-01495-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Accepted: 07/18/2023] [Indexed: 09/02/2023]
Abstract
Transformation via Agrobacterium tumefaciens is the predominant method used to introduce exogenous DNA into plant genomes1,2. Transfer DNA (T-DNA) originating from Agrobacterium can be integrated as a single copy or in complex concatenated forms3,4, but the mechanisms affecting final T-DNA structure remain unknown. Here we demonstrate that inclusion of retrotransposon (RT)-derived sequences in T-DNA can increase T-DNA copy number by more than 50-fold in Arabidopsis thaliana. These additional T-DNA copies are organized into large concatemers, an effect primarily induced by the long terminal repeats (LTRs) of RTs that can be replicated using non-LTR DNA repeats. We found that T-DNA concatenation is dependent on the activity of the DNA repair proteins MRE11, RAD17 and ATR. Finally, we show that T-DNA concatenation can be used to increase the frequency of targeted mutagenesis and gene targeting. Overall, this work uncovers molecular determinants that modulate T-DNA copy number in Arabidopsis and demonstrates the utility of inducing T-DNA concatenation for plant gene editing.
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Affiliation(s)
- Lauren Dickinson
- Department of Molecular, Cellular and Developmental Biology, Faculty of Arts and Sciences, Yale University, New Haven, CT, USA
| | - Wenxin Yuan
- Department of Molecular, Cellular and Developmental Biology, Faculty of Arts and Sciences, Yale University, New Haven, CT, USA
| | - Chantal LeBlanc
- Department of Molecular, Cellular and Developmental Biology, Faculty of Arts and Sciences, Yale University, New Haven, CT, USA
| | - Geoffrey Thomson
- Department of Molecular, Cellular and Developmental Biology, Faculty of Arts and Sciences, Yale University, New Haven, CT, USA
| | - Siyuan Wang
- Department of Genetics, Yale School of Medicine, Yale University, New Haven, CT, USA
- Department of Cell Biology, Yale School of Medicine, Yale University, New Haven, CT, USA
| | - Yannick Jacob
- Department of Molecular, Cellular and Developmental Biology, Faculty of Arts and Sciences, Yale University, New Haven, CT, USA.
- Yale Cancer Center, Yale School of Medicine, Yale University, New Haven, CT, USA.
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2
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Kralemann LEM, de Pater S, Shen H, Kloet SL, van Schendel R, Hooykaas PJJ, Tijsterman M. Distinct mechanisms for genomic attachment of the 5' and 3' ends of Agrobacterium T-DNA in plants. NATURE PLANTS 2022; 8:526-534. [PMID: 35534719 DOI: 10.1038/s41477-022-01147-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Accepted: 03/30/2022] [Indexed: 06/14/2023]
Abstract
Agrobacterium tumefaciens, a pathogenic bacterium capable of transforming plants through horizontal gene transfer, is nowadays the preferred vector for plant genetic engineering. The vehicle for transfer is the T-strand, a single-stranded DNA molecule bound by the bacterial protein VirD2, which guides the T-DNA into the plant's nucleus where it integrates. How VirD2 is removed from T-DNA, and which mechanism acts to attach the liberated end to the plant genome is currently unknown. Here, using newly developed technology that yields hundreds of T-DNA integrations in somatic tissue of Arabidopsis thaliana, we uncover two redundant mechanisms for the genomic capture of the T-DNA 5' end. Different from capture of the 3' end of the T-DNA, which is the exclusive action of polymerase theta-mediated end joining (TMEJ), 5' attachment is accomplished either by TMEJ or by canonical non-homologous end joining (cNHEJ). We further find that TMEJ needs MRE11, whereas cNHEJ requires TDP2 to remove the 5' end-blocking protein VirD2. As a consequence, T-DNA integration is severely impaired in plants deficient for both MRE11 and TDP2 (or other cNHEJ factors). In support of MRE11 and cNHEJ specifically acting on the 5' end, we demonstrate rescue of the integration defect of double-deficient plants by using T-DNAs that are capable of forming telomeres upon 3' capture. Our study provides a mechanistic model for how Agrobacterium exploits the plant's own DNA repair machineries to transform it.
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Affiliation(s)
| | - Sylvia de Pater
- Institute of Biology Leiden, Leiden University, Leiden, The Netherlands
| | - Hexi Shen
- School of Municipal and Environmental Engineering, Shandong Jianzhu University, Jinan, Shandong, China
| | - Susan L Kloet
- Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Robin van Schendel
- Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Paul J J Hooykaas
- Institute of Biology Leiden, Leiden University, Leiden, The Netherlands
| | - Marcel Tijsterman
- Institute of Biology Leiden, Leiden University, Leiden, The Netherlands.
- Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands.
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3
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Sahab S, Taylor N. Studies on Pure Mlb ® (Multiple Left Border) Technology and Its Impact on Vector Backbone Integration in Transgenic Cassava. FRONTIERS IN PLANT SCIENCE 2022; 13:816323. [PMID: 35185986 PMCID: PMC8855067 DOI: 10.3389/fpls.2022.816323] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Accepted: 01/14/2022] [Indexed: 06/14/2023]
Abstract
Imperfect T-DNA processing is common during Agrobacterium-mediated transformation, which integrates vector backbone sequences into the plant genome. However, regulatory restrictions prevent such transgenic plants from being developed for commercial deployment. The binary vector pCAMBIA2300 was modified by incorporating multiple left border (Mlb®) repeats and was tested in BY2 cells, tobacco, and cassava plants to address this issue. PCR analyses confirmed a twofold increase in the vector backbone free events in the presence of triple left borders in all three systems tested. Vector backbone read-through past the LB was reduced significantly; however, the inclusion of Mlbs® did not effectively address the beyond right border read-through. Also, Mlbs® increased the frequency of single-copy and vector backbone free events (clean events) twice compared to a single LB construct. Here, we briefly narrate the strength and limitations of using Mlb® technology and reporter genes in reducing the vector backbone transfer in transgenic events.
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Affiliation(s)
- Sareena Sahab
- Agriculture Victoria Research, AgriBio, Centre for AgriBioscience, Bundoora, VIC, Australia
- Donald Danforth Plant Science Center, St. Louis, MO, United States
| | - Nigel Taylor
- Donald Danforth Plant Science Center, St. Louis, MO, United States
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4
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Li X, Yang Q, Peng L, Tu H, Lee LY, Gelvin SB, Pan SQ. Agrobacterium-delivered VirE2 interacts with host nucleoporin CG1 to facilitate the nuclear import of VirE2-coated T complex. Proc Natl Acad Sci U S A 2020; 117:26389-26397. [PMID: 33020260 PMCID: PMC7584991 DOI: 10.1073/pnas.2009645117] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Agrobacterium tumefaciens is the causal agent of crown gall disease. The bacterium is capable of transferring a segment of single-stranded DNA (ssDNA) into recipient cells during the transformation process, and it has been widely used as a genetic modification tool for plants and nonplant organisms. Transferred DNA (T-DNA) has been proposed to be escorted by two virulence proteins, VirD2 and VirE2, as a nucleoprotein complex (T-complex) that targets the host nucleus. However, it is not clear how such a proposed large DNA-protein complex is delivered through the host nuclear pore in a natural setting. Here, we studied the natural nuclear import of the Agrobacterium-delivered ssDNA-binding protein VirE2 inside plant cells by using a split-GFP approach with a newly constructed T-DNA-free strain. Our results demonstrate that VirE2 is targeted into the host nucleus in a VirD2- and T-DNA-dependent manner. In contrast with VirD2 that binds to plant importin α for nuclear import, VirE2 directly interacts with the host nuclear pore complex component nucleoporin CG1 to facilitate its nuclear uptake and the transformation process. Our data suggest a cooperative nuclear import model in which T-DNA is guided to the host nuclear pore by VirD2 and passes through the pore with the assistance of interactions between VirE2 and host nucleoporin CG1. We hypothesize that this large linear nucleoprotein complex (T-complex) is targeted to the nucleus by a "head" guide from the VirD2-importin interaction and into the nucleus by a lateral assistance from the VirE2-nucleoporin interaction.
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Affiliation(s)
- Xiaoyang Li
- Department of Biological Sciences, National University of Singapore, Singapore 117543
| | - Qinghua Yang
- Department of Biological Sciences, National University of Singapore, Singapore 117543
| | - Ling Peng
- Department of Biological Sciences, National University of Singapore, Singapore 117543
| | - Haitao Tu
- School of Stomatology and Medicine, Foshan University, Foshan 528000, China
| | - Lan-Ying Lee
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907
| | - Stanton B Gelvin
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907
| | - Shen Q Pan
- Department of Biological Sciences, National University of Singapore, Singapore 117543;
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5
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Kiyokawa K, Ohmine Y, Yunoki K, Yamamoto S, Moriguchi K, Suzuki K. Enhanced Agrobacterium-mediated transformation revealed attenuation of exogenous plasmid DNA installation in recipient bacteria by exonuclease VII and SbcCD. Genes Cells 2020; 25:663-674. [PMID: 32799424 DOI: 10.1111/gtc.12802] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Revised: 08/06/2020] [Accepted: 08/06/2020] [Indexed: 11/26/2022]
Abstract
In DNA transfer via type IV secretion system (T4SS), relaxase enzyme releases linear ssDNA in donor cells and recircularizes in recipient cells. Using VirB/D4 T4SS, Agrobacterium cells can transfer an IncQ-type plasmid depending on Mob relaxase and a model T-DNA plasmid depending on VirD2 relaxase. Mobilization to Escherichia coli of the former plasmid is much more efficient than that of the latter, whereas an entirely reverse relationship is observed in transfer to yeast. These data suggest that either plasmid recircularization or conversion of ssDNA to dsDNA in the recipient bacterial cells is a rate-limiting step of the transfer. In this study, we examined involvement of exonuclease genes in the plasmid acceptability. By the VirD2-dependent T-DNA plasmid, E. coli sbcDΔ and sbcCΔ mutant strains produced threefold more exconjugants, and a sbcDΔ xseAΔ mutant strain yielded eightfold more exconjugants than their wild-type strain. In contrast to the enhancing effect on the VirD2-mediated transfer, the mutations exhibited a subtle effect on the Mob-mediated transfer. These results support our working hypothesis that VirD2 can transport its substrate ssDNA efficiently to recipient cells and that recipient nucleases degrade the ssDNA because VirD2 has some defect(s) in the circularization and completion of complementary DNA synthesis.
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Affiliation(s)
- Kazuya Kiyokawa
- Program of Basic Biology, Graduate School of Integrated Sciences for Life, Hiroshima University, Hiroshima, Japan.,Department of Biological Science, Graduate School of Science, Hiroshima University, Hiroshima, Japan
| | - Yuta Ohmine
- Department of Biological Science, Graduate School of Science, Hiroshima University, Hiroshima, Japan
| | - Kazuya Yunoki
- Department of Biological Science, Graduate School of Science, Hiroshima University, Hiroshima, Japan
| | - Shinji Yamamoto
- Department of Biological Science, Graduate School of Science, Hiroshima University, Hiroshima, Japan
| | - Kazuki Moriguchi
- Program of Basic Biology, Graduate School of Integrated Sciences for Life, Hiroshima University, Hiroshima, Japan.,Department of Biological Science, Graduate School of Science, Hiroshima University, Hiroshima, Japan
| | - Katsunori Suzuki
- Program of Basic Biology, Graduate School of Integrated Sciences for Life, Hiroshima University, Hiroshima, Japan.,Department of Biological Science, Graduate School of Science, Hiroshima University, Hiroshima, Japan
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6
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Li X, Zhu T, Tu H, Pan SQ. Agrobacterium VirE3 Uses Its Two Tandem Domains at the C-Terminus to Retain Its Companion VirE2 on the Cytoplasmic Side of the Host Plasma Membrane. FRONTIERS IN PLANT SCIENCE 2020; 11:464. [PMID: 32373148 PMCID: PMC7187210 DOI: 10.3389/fpls.2020.00464] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2020] [Accepted: 03/30/2020] [Indexed: 05/30/2023]
Abstract
Agrobacterium tumefaciens is the causal agent of crown gall disease in nature; in the laboratory the bacterium is widely used for plant genetic modification. The bacterium delivers a single-stranded transferred DNA (T-DNA) and a group of crucial virulence proteins into host cells. A putative T-complex is formed inside host cells that is composed of T-DNA and virulence proteins VirD2 and VirE2, which protect the foreign DNA from degradation and guide its way into the host nucleus. However, little is known about how the T-complex is assembled inside host cells. We combined the split-GFP and split-sfCherry labeling systems to study the interaction of Agrobacterium-delivered VirE2 and VirE3 in host cells. Our results indicated that VirE2 co-localized with VirE3 on the cytoplasmic side of the host cellular membrane upon the delivery. We identified and characterized two tandem domains at the VirE3 C-terminus that interacted with VirE2 in vitro. Deletion of these two domains abolished the VirE2 accumulation on the host plasma membrane and affected the transformation. Furthermore, the two VirE2-interacting domains of VirE3 exhibited different affinities with VirE2. Collectively, this study demonstrates that the anchorage protein VirE3 uses the two tandem VirE2-interacting domains to facilitate VirE2 protection for T-DNA at the cytoplasmic side of the host cell entrance.
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Affiliation(s)
- Xiaoyang Li
- Department of Biological Sciences, National University of Singapore, Singapore, Singapore
| | - Tingting Zhu
- Department of Biological Sciences, National University of Singapore, Singapore, Singapore
| | - Haitao Tu
- School of Stomatology and Medicine, Foshan Institute of Molecular Bio-Engineering, Foshan University, Foshan, China
| | - Shen Q. Pan
- Department of Biological Sciences, National University of Singapore, Singapore, Singapore
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7
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Agrobacterium-mediated horizontal gene transfer: Mechanism, biotechnological application, potential risk and forestalling strategy. Biotechnol Adv 2018; 37:259-270. [PMID: 30579929 DOI: 10.1016/j.biotechadv.2018.12.008] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2018] [Revised: 12/18/2018] [Accepted: 12/18/2018] [Indexed: 11/20/2022]
Abstract
The extraordinary capacity of Agrobacterium to transfer its genetic material to host cell makes it evolve from phytopathogen to a powerful transgenic vector. Agrobacterium-mediated stable transformation is widely used as the preferred method to create transgenic plants for molecular plant biology research and crop breeding. Recent years, both mechanism and application of Agrobacterium-mediated horizontal gene transfer have made significant progresses, especially Agrobacterium-mediated transient transformation was developed for plant biotechnology industry to produce recombinant proteins. Agrobacterium strains are almost used and saved not only by each of microbiology and molecular plant labs, but also by many of plant biotechnology manufacturers. Agrobacterium is able to transfer its genetic material to a broad range of hosts, including plant and non-plant hosts. As a consequence, the concern of environmental risk associated with the accidental release of genetically modified Agrobacterium arises. In this article, we outline the recent progress in the molecular mechanism of Agrobacterium-meditated gene transfer, focus on the application of Agrobacterium-mediated horizontal gene transfer, and review the potential risk associated with Agrobacterium-meditated gene transfer. Based on the comparison between the infecting process of Agrobacterium as a pathogen and the transgenic process of Agrobacterium as a transgenic vector, we realize that chemotaxis is the distinct difference between these two biological processes and thus discuss the possible role of chemotaxis in forestalling the potential risk of Agrobacterium-meditated horizontal gene transfer to non-target plant species.
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8
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Li X, Tu H, Pan SQ. Agrobacterium Delivers Anchorage Protein VirE3 for Companion VirE2 to Aggregate at Host Entry Sites for T-DNA Protection. Cell Rep 2018; 25:302-311.e6. [PMID: 30304671 DOI: 10.1016/j.celrep.2018.09.023] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2018] [Revised: 08/13/2018] [Accepted: 09/07/2018] [Indexed: 01/21/2023] Open
Abstract
Agrobacterium tumefaciens transfers oncogenic DNA (T-DNA) and effector proteins into various host plants. T-DNA is generated inside the bacteria and subsequently delivered into plant cells along with the companion effectors VirD2, VirE2, and VirE3. However, it is not clear how the T-complex consisting of VirD2 and VirE2 is assembled inside plant cells. Here, we report that the effector protein VirE3 localized to plant plasma membranes as an anchorage through a conserved α-helical-bundle domain. VirE3 interacted with itself and enabled VirE2 accumulation at host entry sites through direct interactions. VirE3 was critical for VirE2 function in T-DNA protection. Our data indicate that VirE3 functions as a previously unrecognized anchorage protein consisting of membrane-binding, self-interacting, and VirE2-interacting domains. Both VirE2 and VirE3 are conserved among Agrobacterium and rhizobia species but not other organisms, suggesting that a group of anchorage proteins have been generated through evolution to facilitate the nucleoprotein assembly at plant membranes.
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Affiliation(s)
- Xiaoyang Li
- Department of Biological Sciences, National University of Singapore, 10 Science Drive 4, Singapore 117543, Singapore
| | - Haitao Tu
- Foshan Institute of Molecular Bio-Engineering, School of Stomatology and Medicine, Foshan University, Foshan 528000, China
| | - Shen Q Pan
- Department of Biological Sciences, National University of Singapore, 10 Science Drive 4, Singapore 117543, Singapore.
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9
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Sardesai N, Foulk S, Chen W, Wu H, Etchison E, Gupta M. Coexpression of octopine and succinamopine Agrobacterium virulence genes to generate high quality transgenic events in maize by reducing vector backbone integration. Transgenic Res 2018; 27:539-550. [PMID: 30293127 DOI: 10.1007/s11248-018-0097-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2018] [Accepted: 09/25/2018] [Indexed: 10/28/2022]
Abstract
Agrobacterium-mediated transformation is a complex process that is widely utilized for generating transgenic plants. However, one of the major concerns of this process is the frequent presence of undesirable T-DNA vector backbone sequences in the transgenic plants. To mitigate this deficiency, a ternary strain of A. tumefaciens was modified to increase the precision of T-DNA border nicking such that the backbone transfer is minimized. This particular strain supplemented the native succinamopine VirD1/VirD2 of EHA105 with VirD1/VirD2 derived from an octopine source (pTi15955), the same source as the binary T-DNA borders tested here, residing on a ternary helper plasmid containing an extra copy of the succinamopine VirB/C/G operons and VirD1. Transformation of maize immature embryos was carried out with two different test constructs, pDAB101556 and pDAB111437, bearing the reporter YFP gene and insecticidal toxin Cry1Fa gene, respectively, contained in the VirD-supplemented and regular control ternary strains. Molecular analyses of ~ 700 transgenic events revealed a significant 2.6-fold decrease in events containing vector backbone sequences, from 35.7% with the control to 13.9% with the VirD-supplemented strain for pDAB101556 and from 24.9% with the control to 9.3% with the VirD-supplemented strain for pDAB111437, without compromising transformation efficiency. In addition, while the number of single copy events recovered was similar, there was a 24-26% increase in backbone-free events with the VirD-supplemented strain compared to the control strain. Thus, supplementing existing VirD1/VirD2 genes in Agrobacterium, to recognize diverse T-DNA borders, proved to be a useful tool to increase the number of high quality events in maize.
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Affiliation(s)
- Nagesh Sardesai
- Dow AgroSciences LLC, 9330 Zionsville Rd, Indianapolis, IN, USA.
| | - Stephen Foulk
- Dow AgroSciences LLC, 9330 Zionsville Rd, Indianapolis, IN, USA
| | - Wei Chen
- Dow AgroSciences LLC, 9330 Zionsville Rd, Indianapolis, IN, USA
| | - Huixia Wu
- Dow AgroSciences LLC, 9330 Zionsville Rd, Indianapolis, IN, USA
| | - Emily Etchison
- Dow AgroSciences LLC, 9330 Zionsville Rd, Indianapolis, IN, USA
| | - Manju Gupta
- Dow AgroSciences LLC, 9330 Zionsville Rd, Indianapolis, IN, USA
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10
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Ohmine Y, Kiyokawa K, Yunoki K, Yamamoto S, Moriguchi K, Suzuki K. Successful Transfer of a Model T-DNA Plasmid to E. coli Revealed Its Dependence on Recipient RecA and the Preference of VirD2 Relaxase for Eukaryotes Rather Than Bacteria as Recipients. Front Microbiol 2018; 9:895. [PMID: 29892270 PMCID: PMC5985610 DOI: 10.3389/fmicb.2018.00895] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Accepted: 04/18/2018] [Indexed: 11/13/2022] Open
Abstract
In Agrobacterium-mediated transformation (AMT) of plants, a single-strand (ss) T-DNA covalently linked with a VirD2 protein moves through a bacterial type IV secretion channel called VirB/D4. This transport system originates from conjugal plasmid transfer systems of bacteria. The relaxase VirD2 and its equivalent protein Mob play essential roles in T-DNA transfer and mobilizable plasmid transfer, respectively. In this study, we attempted to transfer a model T-DNA plasmid, which contained no left border but had a right border sequence as an origin of transfer, and a mobilizable plasmid through the VirB/D4 apparatus to Escherichia coli, Agrobacterium and yeast to compare VirD2-driven transfer with Mob-driven one. AMT was successfully achieved by both types of transfer to the three recipient organisms. VirD2-driven AMT of the two bacteria was less efficient than Mob-driven AMT. In contrast, AMT of yeast guided by VirD2 was more efficient than that by Mob. Plasmid DNAs recovered from the VirD2-driven AMT colonies showed the original plasmid structure. These data indicate that VirD2 retains most of its important functions in recipient bacterial cells, but has largely adapted to eukaryotes rather than bacteria. The high AMT efficiency of yeast suggests that VirD2 can also efficiently bring ssDNA to recipient bacterial cells but is inferior to Mob in some process leading to the formation of double-stranded circular DNA in bacteria. This study also revealed that the recipient recA gene was significantly involved in VirD2-dependent AMT, but only partially involved in Mob-dependent AMT. The apparent difference in the recA gene requirement between the two types of AMT suggests that VirD2 is worse at re-circularization to complete complementary DNA synthesis than Mob in bacteria.
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Affiliation(s)
- Yuta Ohmine
- Department of Biological Science, Graduate School of Science, Hiroshima University, Hiroshima, Japan
| | - Kazuya Kiyokawa
- Department of Biological Science, Graduate School of Science, Hiroshima University, Hiroshima, Japan
| | - Kazuya Yunoki
- Department of Biological Science, Graduate School of Science, Hiroshima University, Hiroshima, Japan
| | - Shinji Yamamoto
- Department of Biological Science, Graduate School of Science, Hiroshima University, Hiroshima, Japan
| | - Kazuki Moriguchi
- Department of Biological Science, Graduate School of Science, Hiroshima University, Hiroshima, Japan
| | - Katsunori Suzuki
- Department of Biological Science, Graduate School of Science, Hiroshima University, Hiroshima, Japan
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11
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Tu H, Li X, Yang Q, Peng L, Pan SQ. Real-Time Trafficking of Agrobacterium Virulence Protein VirE2 Inside Host Cells. Curr Top Microbiol Immunol 2018; 418:261-286. [PMID: 30182197 DOI: 10.1007/82_2018_131] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
A. tumefaciens delivers T-DNA and virulence proteins, including VirE2, into host plant cells, where T-DNA is proposed to be protected by VirE2 molecules as a nucleoprotein complex (T-complex) and trafficked into the nucleus. VirE2 is a protein that can self-aggregate and contains targeting sequences so that it can efficiently move from outside of a cell to the nucleus. We adopted a split-GFP approach and generated a VirE2-GFP fusion which retains the self-aggregating property and the targeting sequences. The fusion protein is fully functional and can move inside cells in real time in a readily detectable format: fluorescent and unique filamentous aggregates. Upon delivery mediated by the bacterial type IV secretion system (T4SS), VirE2-GFP is internalized into the plant cells via clathrin adaptor complex AP2-mediated endocytosis. Subsequently, VirE2-GFP binds to membrane structures such as the endoplasmic reticulum (ER) and is trafficked within the cell. This enables us to observe the highly dynamic activities of the cell. If a compound, a gene, or a condition affects the cell, the cellular dynamics shown by the VirE2-GFP will be affected and thus readily observed by confocal microscopy. This represents an excellent model to study the delivery and trafficking of an exogenously produced and delivered protein inside a cell in a natural setting in real time. The model may be used to explore the theoretical and applied aspects of natural protein delivery and targeting.
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Affiliation(s)
- Haitao Tu
- School of Stomatology and Medicine, Foshan Institute of Molecular Bio-Engineering, Foshan University, 528000, Foshan, China
| | - Xiaoyang Li
- Department of Biological Sciences, National University of Singapore, 117543, Singapore, Singapore
| | - Qinghua Yang
- Department of Biological Sciences, National University of Singapore, 117543, Singapore, Singapore
| | - Ling Peng
- Department of Biological Sciences, National University of Singapore, 117543, Singapore, Singapore
| | - Shen Q Pan
- Department of Biological Sciences, National University of Singapore, 117543, Singapore, Singapore.
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12
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The Mechanism of T-DNA Integration: Some Major Unresolved Questions. Curr Top Microbiol Immunol 2018; 418:287-317. [DOI: 10.1007/82_2018_98] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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13
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Li X, Pan SQ. Agrobacterium delivers VirE2 protein into host cells via clathrin-mediated endocytosis. SCIENCE ADVANCES 2017; 3:e1601528. [PMID: 28345032 PMCID: PMC5362186 DOI: 10.1126/sciadv.1601528] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2016] [Accepted: 02/09/2017] [Indexed: 05/20/2023]
Abstract
Agrobacterium tumefaciens can cause crown gall tumors on a wide range of host plants. As a natural genetic engineer, the bacterium can transfer both single-stranded DNA (ssDNA) [transferred DNA (T-DNA)] molecules and bacterial virulence proteins into various recipient cells. Among Agrobacterium-delivered proteins, VirE2 is an ssDNA binding protein that is involved in various steps of the transformation process. However, it is not clear how plant cells receive the T-DNA or protein molecules. Using a split-green fluorescent protein approach, we monitored the VirE2 delivery process inside plant cells in real time. We observed that A. tumefaciens delivered VirE2 from the bacterial lateral sides that were in close contact with plant membranes. VirE2 initially accumulated on plant cytoplasmic membranes at the entry points. VirE2-containing membranes were internalized through clathrin-mediated endocytosis to form endomembrane compartments. VirE2 colocalized with the early endosome marker SYP61 but not with the late endosome marker ARA6, suggesting that VirE2 escaped from early endosomes for subsequent trafficking inside the cells. Dual endocytic motifs at the carboxyl-terminal tail of VirE2 were involved in VirE2 internalization and could interact with the μ subunit of the plant clathrin-associated adaptor AP2 complex (AP2M). Both the VirE2 cargo motifs and AP2M were important for the transformation process. Because AP2-mediated endocytosis is well conserved, our data suggest that the A. tumefaciens pathogen hijacks conserved endocytic pathways to facilitate the delivery of virulence factors. This might be important for Agrobacterium to achieve both a wide host range and a high transformation efficiency.
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Affiliation(s)
- Xiaoyang Li
- Department of Biological Sciences, National University of Singapore, 10 Science Drive 4, Singapore 117543, Singapore
| | - Shen Q. Pan
- Department of Biological Sciences, National University of Singapore, 10 Science Drive 4, Singapore 117543, Singapore
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Krenek P, Samajova O, Luptovciak I, Doskocilova A, Komis G, Samaj J. Transient plant transformation mediated by Agrobacterium tumefaciens: Principles, methods and applications. Biotechnol Adv 2015; 33:1024-42. [PMID: 25819757 DOI: 10.1016/j.biotechadv.2015.03.012] [Citation(s) in RCA: 109] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2014] [Revised: 03/05/2015] [Accepted: 03/19/2015] [Indexed: 12/20/2022]
Abstract
Agrobacterium tumefaciens is widely used as a versatile tool for development of stably transformed model plants and crops. However, the development of Agrobacterium based transient plant transformation methods attracted substantial attention in recent years. Transient transformation methods offer several applications advancing stable transformations such as rapid and scalable recombinant protein production and in planta functional genomics studies. Herein, we highlight Agrobacterium and plant genetics factors affecting transfer of T-DNA from Agrobacterium into the plant cell nucleus and subsequent transient transgene expression. We also review recent methods concerning Agrobacterium mediated transient transformation of model plants and crops and outline key physical, physiological and genetic factors leading to their successful establishment. Of interest are especially Agrobacterium based reverse genetics studies in economically important crops relying on use of RNA interference (RNAi) or virus-induced gene silencing (VIGS) technology. The applications of Agrobacterium based transient plant transformation technology in biotech industry are presented in thorough detail. These involve production of recombinant proteins (plantibodies, vaccines and therapeutics) and effectoromics-assisted breeding of late blight resistance in potato. In addition, we also discuss biotechnological potential of recombinant GFP technology and present own examples of successful Agrobacterium mediated transient plant transformations.
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Affiliation(s)
- Pavel Krenek
- Centre of the Region Haná for Biotechnological and Agricultural Research, Department of Cell Biology, Faculty of Science, Palacký University, Šlechtitelů 27, CZ-783 71 Olomouc, Czech Republic.
| | - Olga Samajova
- Centre of the Region Haná for Biotechnological and Agricultural Research, Department of Cell Biology, Faculty of Science, Palacký University, Šlechtitelů 27, CZ-783 71 Olomouc, Czech Republic.
| | - Ivan Luptovciak
- Centre of the Region Haná for Biotechnological and Agricultural Research, Department of Cell Biology, Faculty of Science, Palacký University, Šlechtitelů 27, CZ-783 71 Olomouc, Czech Republic.
| | - Anna Doskocilova
- Centre of the Region Haná for Biotechnological and Agricultural Research, Department of Cell Biology, Faculty of Science, Palacký University, Šlechtitelů 27, CZ-783 71 Olomouc, Czech Republic.
| | - George Komis
- Centre of the Region Haná for Biotechnological and Agricultural Research, Department of Cell Biology, Faculty of Science, Palacký University, Šlechtitelů 27, CZ-783 71 Olomouc, Czech Republic.
| | - Jozef Samaj
- Centre of the Region Haná for Biotechnological and Agricultural Research, Department of Cell Biology, Faculty of Science, Palacký University, Šlechtitelů 27, CZ-783 71 Olomouc, Czech Republic.
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15
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Rolloos M, Dohmen MHC, Hooykaas PJJ, van der Zaal BJ. Involvement of Rad52 in T-DNA circle formation duringAgrobacterium tumefaciens-mediated transformation ofSaccharomyces cerevisiae. Mol Microbiol 2014; 91:1240-51. [DOI: 10.1111/mmi.12531] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/24/2014] [Indexed: 11/26/2022]
Affiliation(s)
- Martijn Rolloos
- Department of Molecular and Developmental Genetics; nstitute of Biology Leiden; Leiden Sylviusweg 72, 2333 BE The Netherlands
| | - Marius H. C. Dohmen
- Department of Molecular and Developmental Genetics; nstitute of Biology Leiden; Leiden Sylviusweg 72, 2333 BE The Netherlands
| | - Paul J. J. Hooykaas
- Department of Molecular and Developmental Genetics; nstitute of Biology Leiden; Leiden Sylviusweg 72, 2333 BE The Netherlands
| | - Bert J. van der Zaal
- Department of Molecular and Developmental Genetics; nstitute of Biology Leiden; Leiden Sylviusweg 72, 2333 BE The Netherlands
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16
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Li X, Yang Q, Tu H, Lim Z, Pan SQ. Direct visualization of Agrobacterium-delivered VirE2 in recipient cells. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2014; 77:487-95. [PMID: 24299048 PMCID: PMC4282531 DOI: 10.1111/tpj.12397] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2013] [Revised: 11/15/2013] [Accepted: 11/27/2013] [Indexed: 05/18/2023]
Abstract
Agrobacterium tumefaciens is a natural genetic engineer widely used to deliver DNA into various recipients, including plant, yeast and fungal cells. The bacterium can transfer single-stranded DNA molecules (T-DNAs) and bacterial virulence proteins, including VirE2. However, neither the DNA nor the protein molecules have ever been directly visualized after the delivery. In this report, we adopted a split-GFP approach: the small GFP fragment (GFP11) was inserted into VirE2 at a permissive site to create the VirE2-GFP11 fusion, which was expressed in A. tumefaciens; and the large fragment (GFP1-10) was expressed in recipient cells. Upon delivery of VirE2-GFP11 into the recipient cells, GFP fluorescence signals were visualized. VirE2-GFP11 was functional like VirE2; the GFP fusion movement could indicate the trafficking of Agrobacterium-delivered VirE2. As the natural host, all plant cells seen under a microscope received the VirE2 protein in a leaf-infiltration assay; most of VirE2 moved at a speed of 1.3-3.1 μm sec⁻¹ in a nearly linear direction, suggesting an active trafficking process. Inside plant cells, VirE2-GFP formed filamentous structures of different lengths, even in the absence of T-DNA. As a non-natural host recipient, 51% of yeast cells received VirE2, which did not move inside yeast. All plant cells seen under a microscope transiently expressed the Agrobacterium-delivered transgene, but only 0.2% yeast cells expressed the transgene. This indicates that Agrobacterium is a more efficient vector for protein delivery than T-DNA transformation for a non-natural host recipient: VirE2 trafficking is a limiting factor for the genetic transformation of a non-natural host recipient. The split-GFP approach could enable the real-time visualization of VirE2 trafficking inside recipient cells.
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Affiliation(s)
- Xiaoyang Li
- Department of Biological Sciences, National University of SingaporeSingapore, 117543, Singapore
| | - Qinghua Yang
- Department of Biological Sciences, National University of SingaporeSingapore, 117543, Singapore
| | - Haitao Tu
- Department of Biological Sciences, National University of SingaporeSingapore, 117543, Singapore
| | - Zijie Lim
- Department of Biological Sciences, National University of SingaporeSingapore, 117543, Singapore
| | - Shen Q Pan
- Department of Biological Sciences, National University of SingaporeSingapore, 117543, Singapore
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van Kregten M, Lindhout BI, Hooykaas PJJ, van der Zaal BJ. Agrobacterium-mediated T-DNA transfer and integration by minimal VirD2 consisting of the relaxase domain and a type IV secretion system translocation signal. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2009; 22:1356-1365. [PMID: 19810805 DOI: 10.1094/mpmi-22-11-1356] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The VirD2 protein of Agrobacterium tumefaciens is essential for processing and transport of the T-DNA. It has at least three functional domains: a relaxase domain at the N terminus, a bipartite nuclear localization signal (NLS), and a sequence called omega at the C terminus. We confirm here that deletions of the C-terminal part of VirD2 led to lack of transfer of T-DNA but, for the first time, we report that virulence is restored when these truncations are supplemented at the C terminus by a short translocation signal from the VirF protein. The lack of virulence of C-terminal deletions suggests that the C-terminal part contains all or part of the translocation signal of VirD2. Using a novel series of mutant VirD2 proteins, the C-terminal half of VirD2 was further investigated. We demonstrate that the C-terminal 40 amino acids of VirD2, which include the NLS and omega, contain all or part of the translocation domain necessary for transport of VirD2 into plant cells, while another element is present in the middle of the protein. The finding that a type IV secretion system transport signal at the C terminus of VirD2 is necessary for virulence provides evidence for the role of VirD2 as a pilot protein driving translocation of the T-strand.
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Affiliation(s)
- Maartje van Kregten
- Clusius Laboratory, Department of Molecular and Developmental Genetics, Institute of Biology Leiden, Leiden University, Wassenaarseweg 64, 2333 AL Leiden, The Netherlands
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18
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Garcillán-Barcia MP, Francia MV, de la Cruz F. The diversity of conjugative relaxases and its application in plasmid classification. FEMS Microbiol Rev 2009; 33:657-87. [PMID: 19396961 DOI: 10.1111/j.1574-6976.2009.00168.x] [Citation(s) in RCA: 375] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
Bacterial conjugation is an efficient and sophisticated mechanism of DNA transfer among bacteria. While mobilizable plasmids only encode a minimal MOB machinery that allows them to be transported by other plasmids, conjugative plasmids encode a complete set of transfer genes (MOB1T4SS). The only essential ingredient of the MOB machinery is the relaxase, the protein that initiates and terminates conjugative DNA processing. In this review we compared the sequences and properties of the relaxase proteins contained in gene sequence databases. Proteins were arranged in families and phylogenetic trees constructed from the family alignments. This allowed the classification of conjugative transfer systems in six MOB families:MOB(F), MOB(H), MOB(Q), MOB(C), MOB(P) and MOB(V). The main characteristics of each family were reviewed. The phylogenetic relationships of the coupling proteins were also analysed and resulted in phylogenies congruent to those of the cognate relaxases. We propose that the sequences of plasmid relaxases can be used for plasmid classification. We hope our effort will provide researchers with a useful tool for further mining and analysing the plasmid universe both experimentally and in silico.
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Affiliation(s)
- María Pilar Garcillán-Barcia
- Departamento de Biología Molecular e Instituto de Biomedicina y Biotecnología de Cantabria, Universidad de Cantabria-CSIC-IDICAN, Santander, Spain
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19
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20
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Association of the Agrobacterium T-DNA-protein complex with plant nucleosomes. Proc Natl Acad Sci U S A 2008; 105:15429-34. [PMID: 18832163 DOI: 10.1073/pnas.0805641105] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Agrobacterium represents the only natural example of transkingdom transfer of genetic information, from bacteria to plants. Before the bacterial transferred DNA (T-DNA) can integrate into the plant genome, it should be targeted to and bind the host chromatin. However, the T-DNA association with the host chromatin has not been demonstrated. Here, we study T-DNA binding to plant nucleosomes in vitro and show that it is mediated by bacterial and host proteins associated with the T-DNA. The main factor that determines nucleosomal binding of the T-DNA is the cellular VirE2-interacting protein 1 (VIP1), which functions as a molecular link between the T-DNA-associated bacterial virulence protein VirE2 and core histones. The presence of both VIP1 and VirE2 is required for association of the T-DNA with mononucleosomes in which the DNA molecule exists as a tripartite complex DNA-VirE2-VIP1. Furthermore, this nucleosome-associated ternary complex can bind another bacterial virulence factor, VirF, which is an F-box protein known to target both VirE2 and VIP1 for proteasomal degradation and uncoat the T-DNA.
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21
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Guo M, Hou Q, Hew CL, Pan SQ. Agrobacterium VirD2-binding protein is involved in tumorigenesis and redundantly encoded in conjugative transfer gene clusters. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2007; 20:1201-1212. [PMID: 17918622 DOI: 10.1094/mpmi-20-10-1201] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Agrobacterium tumefaciens can transfer oncogenic T-DNA into plant cells; T-DNA transfer is mechanistically similar to a conjugation process. VirD2 is the pilot protein that guides the transfer, because it is covalently associated with single-stranded T-DNA to form the transfer substrate T-complex. We used the VirD2 protein as an affinity ligand to isolate VirD2-binding proteins (VBPs). By pull-down assays and peptide-mass-fingerprint matching, we identified an A. tumefaciens protein designated VBP1 that could bind VirD2 directly. Genome-wide sequence analysis showed that A. tumefaciens has two additional genes encoding proteins highly similar to VBP1, designated vbp2 and vbp3. Like VBP1, both VBP2 and VBP3 also could bind VirD2; all three VBPs contain a putative nucleotidyltransferase motif. Mutational analysis of vbp demonstrated that the three vbp genes could functionally complement each other. Consequently, only inactivation of all three vbp genes highly attenuated the bacterial ability to cause tumors on plants. Although vbp1 is harbored on the megaplasmid pAtC58, vbp2 and vbp3 reside on the linear chromosome. The vbp genes are clustered with conjugative transfer genes, suggesting linkage between the conjugation and virulence factor. The three VBPs appear to contain C-terminal positively charged residues, often present in the transfer substrate proteins of type IV secretion systems. Inactivation of the three vbp genes did not affect the T-strand production. Our data indicate that VBP is a newly identified virulence factor that may affect the transfer process subsequent to T-DNA production.
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Affiliation(s)
- Minliang Guo
- Department of Biological Sciences, National University of Singapore, Singapore 117543
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22
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Atmakuri K, Cascales E, Burton OT, Banta LM, Christie PJ. Agrobacterium ParA/MinD-like VirC1 spatially coordinates early conjugative DNA transfer reactions. EMBO J 2007; 26:2540-51. [PMID: 17505518 PMCID: PMC1868908 DOI: 10.1038/sj.emboj.7601696] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2006] [Accepted: 03/22/2007] [Indexed: 11/09/2022] Open
Abstract
Agrobacterium tumefaciens translocates T-DNA through a polar VirB/D4 type IV secretion (T4S) system. VirC1, a factor required for efficient T-DNA transfer, bears a deviant Walker A and other sequence motifs characteristic of ParA and MinD ATPases. Here, we show that VirC1 promotes conjugative T-DNA transfer by stimulating generation of multiple copies per cell of the T-DNA substrate (T-complex) through pairwise interactions with the processing factors VirD2 relaxase, VirC2, and VirD1. VirC1 also associates with the polar membrane and recruits T-complexes to cell poles, the site of VirB/D4 T4S machine assembly. VirC1 Walker A mutations abrogate T-complex generation and polar recruitment, whereas the native protein recruits T-complexes to cell poles independently of other polar processing factors (VirC2, VirD1) or T4S components (VirD4 substrate receptor, VirB channel subunits). We propose that A. tumefaciens has appropriated a progenitor ParA/MinD-like ATPase to promote conjugative DNA transfer by: (i) nucleating relaxosome assembly at oriT-like T-DNA border sequences and (ii) spatially positioning the transfer intermediate at the cell pole to coordinate substrate-T4S channel docking.
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Affiliation(s)
- Krishnamohan Atmakuri
- Departments of Microbiology and Molecular Genetics, University of Texas Medical School at Houston, Houston, TX, USA
| | - Eric Cascales
- Departments of Microbiology and Molecular Genetics, University of Texas Medical School at Houston, Houston, TX, USA
| | - Oliver T Burton
- Department of Biology, Williams College, Williamstown, MA, USA
| | - Lois M Banta
- Department of Biology, Williams College, Williamstown, MA, USA
| | - Peter J Christie
- Departments of Microbiology and Molecular Genetics, University of Texas Medical School at Houston, Houston, TX, USA
- Department of Microbiology and Molecular Genetics, University of Texas Medical School at Houston, 6431 Fannin Street, Houston, TX 77030, USA. Tel.: +1 713 500 5440; Fax: +1 713 500 5499; E-mail:
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23
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Rommens CM, Bougri O, Yan H, Humara JM, Owen J, Swords K, Ye J. Plant-derived transfer DNAs. PLANT PHYSIOLOGY 2005; 139:1338-49. [PMID: 16244143 PMCID: PMC1283770 DOI: 10.1104/pp.105.068692] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
The transfer of DNA from Agrobacterium to plant cell nuclei is initiated by a cleavage reaction within the 25-bp right border of Ti plasmids. In an effort to develop all-native DNA transformation vectors, 50 putative right border alternatives were identified in both plant expressed sequence tags and genomic DNA. Efficacy tests in a tobacco (Nicotiana tabacum) model system demonstrated that 14 of these elements displayed at least 50% of the activity of conventional Agrobacterium transfer DNA borders. Four of the most effective plant-derived right border alternatives were found to be associated with intron-exon junctions. Additional elements were embedded within introns, exons, untranslated trailers, and intergenic DNA. Based on the identification of a single right border alternative in Arabidopsis and three in rice (Oryza sativa), the occurrence of this motif was estimated at a frequency of at least 0.8x10(-8). Modification of plasmid DNA sequences flanking the alternative borders demonstrated that both upstream and downstream sequences play an important role in initiating DNA transfer. Optimal DNA transfer required the elements to be preceded by pyrimidine residues interspaced by AC-rich trinucleotides. Alteration of this organization lowered transformation frequencies by 46% to 93%. Despite their weaker resemblance with left borders, right border alternatives also functioned effectively in terminating DNA transfer, if both associated with an upstream A[C/T]T[C/G]A[A/T]T[G/T][C/T][G/T][C/G]A[C/T][C/T][A/T] domain and tightly linked cytosine clusters at their junctions with downstream DNA. New insights in border region requirements were used to construct an all-native alfalfa (Medicago sativa) transfer DNA vector that can be used for the production of intragenic plants.
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Affiliation(s)
- Caius M Rommens
- J.R. Simplot Company, Simplot Plant Sciences, Boise, IA 83706, USA.
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24
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Jakubowski SJ, Cascales E, Krishnamoorthy V, Christie PJ. Agrobacterium tumefaciens VirB9, an outer-membrane-associated component of a type IV secretion system, regulates substrate selection and T-pilus biogenesis. J Bacteriol 2005; 187:3486-95. [PMID: 15866936 PMCID: PMC1112014 DOI: 10.1128/jb.187.10.3486-3495.2005] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Agrobacterium tumefaciens translocates DNA and protein substrates between cells via a type IV secretion system (T4SS) whose channel subunits include the VirD4 coupling protein, VirB11 ATPase, VirB6, VirB8, VirB2, and VirB9. In this study, we used linker insertion mutagenesis to characterize the contribution of the outer-membrane-associated VirB9 to assembly and function of the VirB/D4 T4SS. Twenty-five dipeptide insertion mutations were classified as permissive for intercellular substrate transfer (Tra+), completely transfer defective (Tra-), or substrate discriminating, e.g., selectively permissive for transfer only of the oncogenic transfer DNA and the VirE2 protein substrates or of a mobilizable IncQ plasmid substrate. Mutations inhibiting transfer of DNA substrates did not affect formation of close contacts of the substrate with inner membrane channel subunits but blocked formation of contacts with the VirB2 and VirB9 channel subunits, which is indicative of a defect in assembly or function of the distal portion of the secretion channel. Several mutations in the N- and C-terminal regions disrupted VirB9 complex formation with the outer-membrane-associated lipoprotein VirB7 or the inner membrane energy sensor VirB10. Several VirB9.i2-producing Tra+ strains failed to elaborate T pilus at detectable levels (Pil-), and three such Tra+ Pil- mutant strains were rendered Tra- upon deletion of virB2, indicating that the cellular form of pilin protein is essential for substrate translocation. Our findings, together with computer-based analyses, support a model in which distinct domains of VirB9 contribute to substrate selection and translocation, establishment of channel subunit contacts, and T-pilus biogenesis.
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Affiliation(s)
- Simon J Jakubowski
- Department of Microbiology and Molecular Genetics, University of Texas Medical School at Houston, 6431 Fannin, Houston, TX 77030, USA
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25
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Dube T, Kovalchuk I, Hohn B, Thomson JA. Agrobacterium tumefaciens-mediated transformation of plants by the pTF-FC2 plasmid is efficient and strictly dependent on the MobA protein. PLANT MOLECULAR BIOLOGY 2004; 55:531-539. [PMID: 15604698 DOI: 10.1007/s11103-004-1159-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
In the transformation of plants by Agrobacterium tumefaciens the VirD2 protein has been shown to pilot T-DNA during its transfer to the plant cell nucleus. Other studies have shown that the MobA protein of plasmid RSF1010 is capable of mediating its transfer from Agrobacterium cells to plant cells by a similar process. We have demonstrated previously that plasmid pTF-FC2, which has some similarity to RSF1010, is also able to transfer DNA efficiently. In this study, we performed a mutational analysis of the roles played by A . tumefaciens VirD2 and pTF-FC2 MobA in DNA transfer-mediated by A. tumefaciens carrying pTF-FC2. We show that MobA+/VirD2+ and MobA+/VirD2- strains were equally proficient in their ability to transfer a pTF-FC2-derived plasmid DNA to plants and to transform them. However, the MobA-/VirD2+ strain showed a DNA transfer efficiency of 0.03% compared with that of the other two strains. This sharply contrasts with our results that VirD2 can rather efficiently cleave the oriT sequence of pFT-FC2 in vitro . We therefore conclude that MobA plays a major VirD2-independent role in plant transformation by pTF-FC2.
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Affiliation(s)
- Thabani Dube
- Department of Molecular and Cell Biology, University of Cape Town, Private Bag Rondebosch, South Africa
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26
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Caryl JA, Smith MCA, Thomas CD. Reconstitution of a staphylococcal plasmid-protein relaxation complex in vitro. J Bacteriol 2004; 186:3374-83. [PMID: 15150222 PMCID: PMC415747 DOI: 10.1128/jb.186.11.3374-3383.2004] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The isolation of plasmid-protein relaxation complexes from bacteria is indicative of the plasmid nicking-closing equilibrium in vivo that serves to ready the plasmids for conjugal transfer. In pC221 and pC223, the components required for in vivo site- and strand-specific nicking at oriT are MobC and MobA. In order to investigate the minimal requirements for nicking in the absence of host-encoded factors, the reactions were reconstituted in vitro. Purified MobA and MobC, in the presence of Mg2+ or Mn2+, were found to nick at oriT with a concomitant phosphorylation-resistant modification at the 5' end of nic. The position of nic is consistent with that determined in vivo. MobA, MobC, and Mg2+ or Mn2+ therefore represent the minimal requirements for nicking activity. Cross-complementation analyses showed that the MobC proteins possess binding specificity for oriT DNA of either plasmid and are able to complement each other in the nicking reaction. Conversely, nicking by the MobA proteins is plasmid specific. This suggests the MobA proteins may encode the nicking specificity determinant.
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Affiliation(s)
- Jamie A Caryl
- Astbury Centre for Structural Molecular Biology, School of Biochemistry and Molecular Biology, University of Leeds, Leeds LS2 9JT, United Kingdom
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27
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Abu-Arish A, Frenkiel-Krispin D, Fricke T, Tzfira T, Citovsky V, Wolf SG, Elbaum M. Three-dimensional reconstruction of Agrobacterium VirE2 protein with single-stranded DNA. J Biol Chem 2004; 279:25359-63. [PMID: 15054095 DOI: 10.1074/jbc.m401804200] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
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 single-stranded 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 three-dimensional reconstruction.
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Affiliation(s)
- Asmahan Abu-Arish
- Department of Materials and Interfaces, Weizmann Institute of Science, Rehovot 76100, Israel
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28
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Tzfira T, Frankman LR, Vaidya M, Citovsky V. Site-specific integration of Agrobacterium tumefaciens T-DNA via double-stranded intermediates. PLANT PHYSIOLOGY 2003; 133:1011-23. [PMID: 14551323 PMCID: PMC281598 DOI: 10.1104/pp.103.032128] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2003] [Revised: 08/28/2003] [Accepted: 08/28/2003] [Indexed: 05/18/2023]
Abstract
Agrobacterium tumefaciens-mediated genetic transformation involves transfer of a single-stranded T-DNA molecule (T strand) into the host cell, followed by its integration into the plant genome. The molecular mechanism of T-DNA integration, the culmination point of the entire transformation process, remains largely obscure. Here, we studied the roles of double-stranded breaks (DSBs) and double-stranded T-DNA intermediates in the integration process. We produced transgenic tobacco (Nicotiana tabacum) plants carrying an I-SceI endonuclease recognition site that, upon cleavage with I-SceI, generates DSB. Then, we retransformed these plants with two A. tumefaciens strains: one that allows transient expression of I-SceI to induce DSB and the other that carries a T-DNA with the I-SceI site and an integration selection marker. Integration of this latter T-DNA as full-length and I-SceI-digested molecules into the DSB site was analyzed in the resulting plants. Of 620 transgenic plants, 16 plants integrated T-DNA into DSB at their I-SceI sites; because DSB induces DNA repair, these results suggest that the invading T-DNA molecules target to the DNA repair sites for integration. Furthermore, of these 16 plants, seven plants incorporated T-DNA digested with I-SceI, which cleaves only double-stranded DNA. Thus, T-strand molecules can be converted into double-stranded intermediates before their integration into the DSB sites within the host cell genome.
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Affiliation(s)
- Tzvi Tzfira
- Department of Biochemistry and Cell Biology, State University of New York, Stony Brook, New York 11794, USA.
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29
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Bakó L, Umeda M, Tiburcio AF, Schell J, Koncz C. The VirD2 pilot protein of Agrobacterium-transferred DNA interacts with the TATA box-binding protein and a nuclear protein kinase in plants. Proc Natl Acad Sci U S A 2003; 100:10108-13. [PMID: 12900506 PMCID: PMC187781 DOI: 10.1073/pnas.1733208100] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2003] [Indexed: 11/18/2022] Open
Abstract
The bacterial virulence protein VirD2 plays an important role in nuclear import and chromosomal integration of Agrobacterium-transferred DNA in fungal, plant, animal, and human cells. Here we show that in nuclei of alfalfa cells, VirD2 interacts with and is phosphorylated by CAK2Ms, a conserved plant ortholog of cyclin-dependent kinase-activating kinases. CAK2Ms binds to and phosphorylates the C-terminal regulatory domain of RNA polymerase II largest subunit, which can recruit the TATA box-binding protein. VirD2 is found in tight association with the TATA box-binding protein in vivo. These results indicate that recognition of VirD2 is mediated by widely conserved nuclear factors in eukaryotes.
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Affiliation(s)
- László Bakó
- Max Planck Institute for Plant Breeding Research, Carl-von-Linne-Weg 10, D-50829 Cologne (Köln), Germany
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30
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Zhong Z, Caspi R, Helinski D, Knauf V, Sykes S, O'Byrne C, Shea TP, Wilkinson JE, DeLoughery C, Toukdarian A. Nucleotide sequence based characterizations of two cryptic plasmids from the marine bacterium Ruegeria isolate PR1b. Plasmid 2003; 49:233-52. [PMID: 12749836 DOI: 10.1016/s0147-619x(03)00014-3] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Two plasmids, 76 and 148 kb in size, isolated from Ruegeria strain PR1b were entirely sequenced. These are the first plasmids to be characterized from this genus of marine bacteria. Sequence analysis revealed a biased distribution of function among the putative proteins encoded on the two plasmids. The smaller plasmid, designated pSD20, encodes a large number of putative proteins involved in polysaccharide biosynthesis and export. The larger plasmid, designated pSD25, primarily encodes putative proteins involved in the transport of small molecules and in DNA mobilization. Sequence analysis revealed uncommon potential replication systems on both plasmids. pSD25, the first repABC-type replicon isolated from the marine environment, actually contains two repABC-type replicons. pSD20 contains a complex replication region, including a replication origin and initiation protein similar to iteron-containing plasmids (such as pSW500 from the plant pathogen Erwinia stewartii) linked to putative RepA and RepB stabilization proteins of a repABC-type replicon and is highly homologous to a plasmid from the phototrophic bacterium Rhodobacter sphaeroides. Given the nature of the putative proteins encoded by both plasmids it is possible that these plasmids enhance the metabolic and physiological flexibility of the host bacterium, and thus its adaptation to the marine sediment environment.
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Affiliation(s)
- Zhenping Zhong
- Division of Biology, University of California, San Diego, La Jolla, CA 92093-0322, USA
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31
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Gelvin SB. Agrobacterium-mediated plant transformation: the biology behind the "gene-jockeying" tool. Microbiol Mol Biol Rev 2003; 67:16-37, table of contents. [PMID: 12626681 PMCID: PMC150518 DOI: 10.1128/mmbr.67.1.16-37.2003] [Citation(s) in RCA: 620] [Impact Index Per Article: 29.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Agrobacterium tumefaciens and related Agrobacterium species have been known as plant pathogens since the beginning of the 20th century. However, only in the past two decades has the ability of Agrobacterium to transfer DNA to plant cells been harnessed for the purposes of plant genetic engineering. Since the initial reports in the early 1980s using Agrobacterium to generate transgenic plants, scientists have attempted to improve this "natural genetic engineer" for biotechnology purposes. Some of these modifications have resulted in extending the host range of the bacterium to economically important crop species. However, in most instances, major improvements involved alterations in plant tissue culture transformation and regeneration conditions rather than manipulation of bacterial or host genes. Agrobacterium-mediated plant transformation is a highly complex and evolved process involving genetic determinants of both the bacterium and the host plant cell. In this article, I review some of the basic biology concerned with Agrobacterium-mediated genetic transformation. Knowledge of fundamental biological principles embracing both the host and the pathogen have been and will continue to be key to extending the utility of Agrobacterium for genetic engineering purposes.
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Affiliation(s)
- Stanton B Gelvin
- Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907-1392, USA.
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32
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Pantoja M, Chen L, Chen Y, Nester EW. Agrobacterium type IV secretion is a two-step process in which export substrates associate with the virulence protein VirJ in the periplasm. Mol Microbiol 2002; 45:1325-35. [PMID: 12207700 DOI: 10.1046/j.1365-2958.2002.03098.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Type IV secretion systems are virulence determinants in many bacteria and share extensive homology with many conjugal transfer systems. Although type IV systems and their homologues have been studied widely, the mechanism by which substrates are secreted remains unclear. In Agrobacterium, we show that type IV secretion substrates that lack signal peptides form a soluble complex in the periplasm with the virulence protein VirJ. Additionally, these proteins co-precipitate with constituents of the type IV transporter: the VirB pilus and the VirD4 protein. Our findings suggest that the substrate proteins localized to the periplasm may associate with the pilus in a manner that is mediated by VirJ, and suggest a two-step process for type IV secretion in Agrobacterium. Our analyses of protein-protein interactions in a variety of mutant backgrounds indicate that substrates are probably secreted independently of one another.
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Affiliation(s)
- Mario Pantoja
- Deparetment of Microbiology, University of Washington, Seattle, WA 98195, USA.
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33
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Llosa M, Gomis-Rüth FX, Coll M, de la Cruz Fd F. Bacterial conjugation: a two-step mechanism for DNA transport. Mol Microbiol 2002; 45:1-8. [PMID: 12100543 DOI: 10.1046/j.1365-2958.2002.03014.x] [Citation(s) in RCA: 264] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Bacterial conjugation is a promiscuous DNA transport mechanism. Conjugative plasmids transfer themselves between most bacteria, thus being one of the main causal agents of the spread of antibiotic resistance among pathogenic bacteria. Moreover, DNA can be transferred conjugatively into eukaryotic host cells. In this review, we aim to address several basic questions regarding the DNA transfer mechanism. Conjugation can be visualized as a DNA rolling-circle replication (RCR) system linked to a type IV secretion system (T4SS), the latter being macromolecular transporters widely involved in pathogenic mechanisms. The scheme 'replication + secretion' suggests how the mechanism would work on the DNA substrate and at the bacterial membrane. But, how do these two parts come into contact? Furthermore, how is the DNA transported? T4SS are known to be involved in protein secretion in different organisms, but DNA is a very different macromolecule. The so-called coupling proteins could be the answer to both questions by performing a dual role in conjugation: coupling the two main components of the machinery (RCR and T4SS) and actively mediating DNA transport. We postulate that the T4SS is responsible for transport of the pilot protein (the relaxase) to the recipient. The DNA that is covalently linked to it is initially transported in a passive manner, trailing on the relaxase. We speculate that the pilus appendage could work as a needle, thrusting the substrate proteins to cross one or several membrane barriers into the recipient cytoplasm. This is the first step in conjugation. The second step is the active pumping of the DNA to the recipient, using the already available T4SS transport conduit. It is proposed that this second step is catalysed by the coupling proteins. Our 'shoot and pump' model solves the protein-DNA transport paradox of T4SS.
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Affiliation(s)
- Matxalen Llosa
- Dipartmento de Biología Molecular, Unidad Asociada al CIB-CSIC, Universidad de Cantabria, Santander, Spain.
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Tzfira T, Citovsky V. Partners-in-infection: host proteins involved in the transformation of plant cells by Agrobacterium. Trends Cell Biol 2002; 12:121-9. [PMID: 11859024 DOI: 10.1016/s0962-8924(01)02229-2] [Citation(s) in RCA: 138] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Genetic modification of plant cells by Agrobacterium is the only known natural example of DNA transport between kingdoms. While the bacterial factors involved in Agrobacterium infection have been relatively well characterized, studies of their host cellular partners are just beginning. Here, we describe the plant cell factors that might participate in Agrobacterium-mediated genetic transformation and discuss their possible roles in this process. Because Agrobacterium probably adapts existing cellular processes for its life cycle, identifying the host factors participating in Agrobacterium infection might contribute to a better understanding of such basic biological processes as cell communication, intracellular transport and DNA repair and recombination as well as help expand the host range of Agrobacterium as a genetic engineering tool.
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Affiliation(s)
- Tzvi Tzfira
- Dept of Biochemistry and Cell Biology, State University of New York, Stony Brook, NY 11794-5215, USA.
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35
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Szpirer CY, Faelen M, Couturier M. Mobilization function of the pBHR1 plasmid, a derivative of the broad-host-range plasmid pBBR1. J Bacteriol 2001; 183:2101-10. [PMID: 11222611 PMCID: PMC95108 DOI: 10.1128/jb.183.6.2101-2110.2001] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The pBHR1 plasmid is a derivative of the small (2.6-kb), mobilizable broad-host-range plasmid pBBR1, which was isolated from the gram-negative bacterium Bordetella bronchiseptica (R. Antoine and C. Locht, Mol. Microbiol. 6:1785-1799, 1992). Plasmid pBBR1 consists of two functional cassettes and presents sequence similarities with the transfer origins of several plasmids and mobilizable transposons from gram-positive bacteria. We show that the Mob protein specifically recognizes a 52-bp sequence which contains, in addition to the transfer origin, the promoter of the mob gene. We demonstrate that this gene is autoregulated. The binding of the Mob protein to the 52-bp sequence could thus allow the formation of a protein-DNA complex with a double function: relaxosome formation and mob gene regulation. We show that the Mob protein is a relaxase, and we located the nic site position in vitro. After sequence alignment, the position of the nic site of pBBR1 corresponds with those of the nick sites of the Bacteroides mobilizable transposon Tn4555 and the streptococcal plasmid pMV158. The oriT of the latter is characteristic of a family of mobilizable plasmids that are found in gram-positive bacteria and that replicate by the rolling-circle mechanism. Plasmid pBBR1 thus appears to be a new member of this group, even though it resides in gram-negative bacteria and does not replicate via a rolling-circle mechanism. In addition, we identified two amino acids of the Mob protein necessary for its activity, and we discuss their involvement in the mobilization mechanism.
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Affiliation(s)
- C Y Szpirer
- Laboratoire de Génétique des Procaryotes, Département de Biologie Moléculaire, Université Libre de Bruxelles, B-6041 Gosselies, Belgium.
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36
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Biochemical Genetics. Biochemistry 2001. [DOI: 10.1016/b978-012492543-4/50029-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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37
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Zhu J, Oger PM, Schrammeijer B, Hooykaas PJ, Farrand SK, Winans SC. The bases of crown gall tumorigenesis. J Bacteriol 2000; 182:3885-95. [PMID: 10869063 PMCID: PMC94570 DOI: 10.1128/jb.182.14.3885-3895.2000] [Citation(s) in RCA: 246] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Affiliation(s)
- J Zhu
- Department of Microbiology, Cornell University, Ithaca, NY 14853, USA
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38
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Tzfira T, Citovsky V. From host recognition to T-DNA integration: the function of bacterial and plant genes in the Agrobacterium-plant cell interaction. MOLECULAR PLANT PATHOLOGY 2000; 1:201-12. [PMID: 20572967 DOI: 10.1046/j.1364-3703.2000.00026.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
UNLABELLED Abstract Agrobacterium tumefaciens and its related species, A. rhizogenes and A. vitis, are the only known bacterial pathogens which 'genetically invade' host plants and stably integrate part of their genetic material into the host cell genome. Thus, A. tumefaciens has evolved as a major tool for plant genetic engineering. Furthermore, this unique process of interkingdom DNA transfer has been utilized as a model system for studies of its underlying biological events, such as intercellular signalling, cell-to-cell DNA transport, protein and DNA nuclear import and integration. To date, numerous bacterial proteins and several plant proteins have been implicated in the A. tumefaciens-plant cell interaction. Here, we discuss the molecular interactions among these bacterial and plant factors and their role in the A. tumefaciens-plant cell DNA transfer. Taxonomic relationship: Bacteria; Proteobacteria; alpha subdivision; Rhizobiaceae group; Rhizobiaceae family; Agrobacterium genus. Microbiological properties: Gram-negative, nonsporing, motile, rod-shaped, soil-borne. Related species:A. rhizogenes (causes root formation in infected plants), A. vitis (causes gall formation on grapevines). Disease symptoms: Formation of neoplastic swellings (galls) on plant roots, crowns, trunks and canes. Galls interfere with water and nutrient flow in the plants, and seriously infected plants suffer from weak, stunted growth and low productivity. HOST RANGE One of the widest host ranges known among plant pathogens; can potentially attack all dicotyledonous plant species. Also, under controlled conditions (usually in tissue culture), can infect, albeit with lower efficiency, several monocotyledonous species. Agronomic importance: The disease currently affects plants belonging to the rose family, e.g. apple, pear, peach, cherry, almond, roses, as well as poplar trees (aspen). Useful web site:http://www.bio.purdue.edu/courses/gelvinweb/gelvin.html.
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Affiliation(s)
- T Tzfira
- Department of Biochemistry and Cell Biology, State University of New York, Stony Brook, NY 11794-5215, USA
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39
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Zupan J, Muth TR, Draper O, Zambryski P. The transfer of DNA from agrobacterium tumefaciens into plants: a feast of fundamental insights. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2000; 23:11-28. [PMID: 10929098 DOI: 10.1046/j.1365-313x.2000.00808.x] [Citation(s) in RCA: 227] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Affiliation(s)
- J Zupan
- Department of Plant and Microbial Biology, 111 Koshland Hall, University of California, Berkeley, CA 94720-3102, USA
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40
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Abstract
The phytopathogenic bacterium Agrobacterium tumefaciens genetically transforms plants by transferring a portion of the resident Ti-plasmid, the T-DNA, to the plant. Accompanying the T-DNA into the plant cell is a number of virulence (Vir) proteins. These proteins may aid in T-DNA transfer, nuclear targeting, and integration into the plant genome. Other virulence proteins on the bacterial surface form a pilus through which the T-DNA and the transferred proteins may translocate. Although the roles of these virulence proteins within the bacterium are relatively well understood, less is known about their roles in the plant cell. In addition, the role of plant-encoded proteins in the transformation process is virtually unknown. In this article, I review what is currently known about the functions of virulence and plant proteins in several aspects of the Agrobacterium transformation process.
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Affiliation(s)
- Stanton B. Gelvin
- Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907-1392; e-mail:
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41
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Affiliation(s)
- G Hansen
- Novartis Agribusiness Biotechnology Research, Inc., Research Triangle Park, NC 27709, USA
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42
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Relić B, Andjelković M, Rossi L, Nagamine Y, Hohn B. Interaction of the DNA modifying proteins VirD1 and VirD2 of Agrobacterium tumefaciens: analysis by subcellular localization in mammalian cells. Proc Natl Acad Sci U S A 1998; 95:9105-10. [PMID: 9689041 PMCID: PMC21299 DOI: 10.1073/pnas.95.16.9105] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Interaction between Agrobacterium tumefaciens and plants provides a unique example of interkingdom gene transfer. Agrobacterium, a plant pathogen, is capable to stably transform the plant cell with a segment of its own DNA called T-DNA (transferred DNA). This process depends, among others, on the specialized bacterial virulence proteins VirD1 and VirD2 that excise the T-DNA from its adjacent sequences. Subsequent to transfer to the plant cell, the virulence protein VirD2, through its nuclear localization signal (NLS), is believed to guide the T-DNA to the nucleus. The T-DNA then is integrated into the plant genome. Although both of these proteins are essential for bacterial virulence, physical interaction of them has not been analyzed so far. We studied associations between these proteins by expressing them in mammalian cells and by testing for intracellular localization and colocalization. When expressed in human cells [HeLa, human embryo kidney (HEK) 293], the VirD2 protein homogeneously distributed over the nucleoplasm. The presence of any of two NLSs, on the N and C termini of VirD2, was sufficient for its efficient nuclear localization whereas deletion of both NLSs rendered the protein cytoplasmic. However, this double NLS mutant was translocated to the nucleus in the presence of wild-type VirD2 protein, implying VirD2-VirD2 interaction. The VirD1 protein, by itself localized in the cytoplasm, moved to the nucleus when coexpressed with the VirD2 protein, suggesting VirD1-VirD2 interaction. This interaction was confirmed by coimmunoprecipitation tests. Of interest, both proteins coimported to the nucleus showed a similar, peculiar sublocalization. The data are discussed in terms of functions of the VirD proteins. In addition, coimport of proteins into nuclei is suggested as a useful system in studying individual protein-protein interactions.
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Affiliation(s)
- B Relić
- Friedrich Miescher-Institut, P.O. Box 2543, CH-4002 Basel, Switzerland.
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43
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Affiliation(s)
- A Das
- Department of Biochemistry, University of Minnesota, St. Paul 55108, USA
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44
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Hansen G, Shillito RD, Chilton MD. T-strand integration in maize protoplasts after codelivery of a T-DNA substrate and virulence genes. Proc Natl Acad Sci U S A 1997; 94:11726-30. [PMID: 9326678 PMCID: PMC23615 DOI: 10.1073/pnas.94.21.11726] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
We describe a plant protoplast transformation method that provides transformants with a simple pattern of integration of a foreign gene. The approach is to deliver into plant protoplasts by direct gene transfer the Agrobacterium virulence genes virD1 and virD2 with or without virE2, together with a target plasmid containing a gene of interest flanked by Agrobacterium T-DNA border repeat sequences of 25 bp. We present evidence of T-DNA formation in maize protoplasts and its integration into the maize genome. The frequency of VirD1-VirD2-mediated integration events was about 20-35% of the total number of transformants. The addition of virE2 doubled the transformation efficiency. The method described here is of sufficient efficiency and simplicity to be useful for the production of transgenic plants with single-copy well-defined transgenic inserts.
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Affiliation(s)
- G Hansen
- Novartis, P.O. Box 12257, Research Triangle Park, NC 27709, USA.
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45
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Daugelavicius R, Bamford JK, Grahn AM, Lanka E, Bamford DH. The IncP plasmid-encoded cell envelope-associated DNA transfer complex increases cell permeability. J Bacteriol 1997; 179:5195-202. [PMID: 9260964 PMCID: PMC179380 DOI: 10.1128/jb.179.16.5195-5202.1997] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
IncP-type plasmids are broad-host-range conjugative plasmids. DNA translocation requires DNA transfer-replication functions and additional factors required for mating pair formation (Mpf). The Mpf system is located in the cell membranes and is responsible for DNA transport from the donor to the recipient. The Mpf complex acts as a receptor for IncP-specific phages such as PRD1. In this investigation, we quantify the Mpf complexes on the cell surface by a phage receptor saturation technique. Electrochemical measurements are used to show that the Mpf complex increases cell envelope permeability to lipophilic compounds and ATP. In addition it reduces the ability of the cells to accumulate K+. However, the Mpf complex does not dissipate the membrane voltage. The Mpf complex is rapidly disassembled when intracellular ATP concentration is decreased, as measured by a PRD1 adsorption assay.
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Affiliation(s)
- R Daugelavicius
- Department of Biosciences, Biocenter, University of Helsinki, Finland
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46
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Christie PJ. Agrobacterium tumefaciens T-complex transport apparatus: a paradigm for a new family of multifunctional transporters in eubacteria. J Bacteriol 1997; 179:3085-94. [PMID: 9150199 PMCID: PMC179082 DOI: 10.1128/jb.179.10.3085-3094.1997] [Citation(s) in RCA: 257] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Affiliation(s)
- P J Christie
- Department of Microbiology and Molecular Genetics, The University of Texas Health Science Center at Houston 77030, USA.
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47
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Guzmán LM, Espinosa M. The mobilization protein, MobM, of the streptococcal plasmid pMV158 specifically cleaves supercoiled DNA at the plasmid oriT. J Mol Biol 1997; 266:688-702. [PMID: 9102462 DOI: 10.1006/jmbi.1996.0824] [Citation(s) in RCA: 86] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The streptococcal plasmid pMV158 replicates by the rolling circle mechanism. It encodes a relaxase protein of 494 residues, termed MobM, involved in conjugative mobilization. MobM protein was overproduced, purified, and shown specifically to relax supercoiled pMV158 DNA. The 5'-end and the 3'-end of the nick site introduced by MobM have been determined by sequencing and by primer extension analysis. The nucleophilic attack exerted by MobM is in the 5'-GpT-3' dinucleotide, within the sequence 5'-TAGTGTG/TTA-3'. Upon cleavage, MobM protein remains tightly associated with its target DNA, probably through a covalent bond. The pMV158 oriT did not exhibit homologies with known origins of transfer of plasmids from Gram-negative bacteria. However, several plasmids from Gram-positive hosts have a region identical or very similar to the pMV158 oriT. To our knowledge, this is the first demonstration of a relaxase activity of a mobilization protein from a plasmid replicating by the rolling circle mechanism.
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Affiliation(s)
- L M Guzmán
- Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Cientificas Velázquez, Madrid, Spain
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48
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Baron C, Thorstenson YR, Zambryski PC. The lipoprotein VirB7 interacts with VirB9 in the membranes of Agrobacterium tumefaciens. J Bacteriol 1997; 179:1211-8. [PMID: 9023204 PMCID: PMC178818 DOI: 10.1128/jb.179.4.1211-1218.1997] [Citation(s) in RCA: 88] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
VirB9 and VirB7 are essential components of the putative VirB membrane channel required for transfer of the T-complex from Agrobacterium tumefaciens into plants. In this report, we present a biochemical analysis of their interaction and cellular localization. A comparison of relative electrophoretic mobilities under nonreducing and reducing conditions suggested that they form thiol-sensitive complexes with other proteins. Two-dimensional gel electrophoresis identified one complex as a heterodimer of VirB9 and VirB7 covalently linked by a disulfide bond, as well as VirB7 homodimers and monomers. Immunoprecipitation with VirB9-specific antiserum isolated the heterodimeric VirB9-VirB7 complex. Incubation with reducing agent split the complex into its constituent VirB9 and VirB7, which further confirmed linkage via cysteine residues. The interaction between VirB9 and VirB7 also was observed in the yeast two-hybrid system. Membrane attachment of VirB9-VirB7 may be conferred by lipoprotein modification, since labeling with [3H]palmitic acid in A. tumefaciens verified that VirB7 is a lipoprotein associated with VirB9. VirB9 and VirB7 showed equal distribution between inner and outer membranes, in accord with their proposed association with the transmembrane VirB complex.
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Affiliation(s)
- C Baron
- Department of Plant and Microbial Biology, University of California at Berkeley, 94720, USA
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49
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Hansen G, Chilton MD. "Agrolistic" transformation of plant cells: integration of T-strands generated in planta. Proc Natl Acad Sci U S A 1996; 93:14978-83. [PMID: 8962167 PMCID: PMC26248 DOI: 10.1073/pnas.93.25.14978] [Citation(s) in RCA: 66] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/26/1996] [Indexed: 02/03/2023] Open
Abstract
We describe a novel plant transformation technique, termed "agrolistic," that combines the advantages of the Agrobacterium transformation system with the high efficiency of biolistic DNA delivery. Agrolistic transformation allows integration of the gene of interest without undesired vector sequence. The virulence genes virD1 and virD2 from Agrobacterium tumefaciens that are required in bacteria for excision of T-strands from the tumor-inducing plasmid were placed under the control of the CaMV35S promoter and codelivered with a target plasmid containing border sequences flanking the gene of interest. Transient expression assays in tobacco and in maize cells indicated that vir gene products caused strand-specific nicking in planta at the right border sequence, similar to VirD1/VirD2-catalyzed T-strand excision observed in Agrobacterium. Agrolistically transformed tobacco calli were obtained after codelivery of virD1 and virD2 genes together with a selectable marker flanked by border sequences. Some inserts exhibited right junctions with plant DNA that corresponded precisely to the sequence expected for T-DNA (portion of the tumor-inducing plasmid that is transferred to plant cells) insertion events. We designate these as "agrolistic" inserts, as distinguished from "biolistic" inserts. Both types of inserts were found in some transformed lines. The frequency of agrolistic inserts was 20% that of biolistic inserts.
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Affiliation(s)
- G Hansen
- CIBA-Geigy Corporation, Research Triangle Park, NC 27709.
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50
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Risseeuw E, Franke-van Dijk ME, Hooykaas PJ. Integration of an insertion-type transferred DNA vector from Agrobacterium tumefaciens into the Saccharomyces cerevisiae genome by gap repair. Mol Cell Biol 1996; 16:5924-32. [PMID: 8816506 PMCID: PMC231594 DOI: 10.1128/mcb.16.10.5924] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Recently, it was shown that Agrobacterium tumefaciens can transfer transferred DNA (T-DNA) to Saccharomyces cerevisiae and that this T-DNA, when used as a replacement vector, is integrated via homologous recombination into the yeast genome. To test whether T-DNA can be a suitable substrate for integration via the gap repair mechanism as well, a model system developed for detection of homologous recombination events in plants was transferred to S. cerevisiae. Analysis of the yeast transformants revealed that an insertion type T-DNA vector can indeed be integrated via gap repair. Interestingly, the transformation frequency and the type of recombination events turned out to depend strongly on the orientation of the insert between the borders in such an insertion type T-DNA vector.
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Affiliation(s)
- E Risseeuw
- Clusius Laboratory, Institute of Molecular Plant Sciences, Leiden University, The Netherlands
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