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Tang Y, Zhang Z, Yang Z, Wu J. CRISPR/Cas9 and Agrobacterium tumefaciens virulence proteins synergistically increase efficiency of precise genome editing via homology directed repair in plants. JOURNAL OF EXPERIMENTAL BOTANY 2023; 74:3518-3530. [PMID: 36919203 PMCID: PMC10797490 DOI: 10.1093/jxb/erad096] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2023] [Accepted: 03/13/2023] [Indexed: 06/18/2023]
Abstract
CRISPR/Cas9 genome editing and Agrobacterium tumefaciens-mediated genetic transformation are widely-used plant biotechnology tools derived from bacterial immunity-related systems, each involving DNA modification. The Cas9 endonuclease introduces DNA double-strand breaks (DSBs), and the A. tumefaciens T-DNA is released by the VirD2 endonuclease assisted by VirDl and attached by VirE2, transferred to the plant nucleus and integrated into the genome. Here, we explored the potential for synergy between the two systems and found that Cas9 and three virulence (Vir) proteins achieve precise genome editing via the homology directed repair (HDR) pathway in tobacco and rice plants. Compared with Cas9T (Cas9, VirD1, VirE2) and CvD (Cas9-VirD2) systems, the HDR frequencies of a foreign GFPm gene in the CvDT system (Cas9-VirD2, VirD1, VirE2) increased 52-fold and 22-fold, respectively. Further optimization of the CvDT process with a donor linker (CvDTL) achieved a remarkable increase in the efficiency of HDR-mediated genome editing. Additionally, the HDR efficiency of the three rice endogenous genes ACETOLACTATE SYNTHASE (ALS), PHYTOENE DESATURASE (PDS), and NITROGEN TRANSPORTER 1.1 B (NRT1.1B) increased 24-, 32- and 16-fold, respectively, in the CvDTL system, compared with corresponding Cas9TL (Cas9T process with a donor linker). Our results suggest that collaboration between CRISPR/Cas9 and Agrobacterium-mediated genetic transformation can make great progress towards highly efficient and precise genome editing via the HDR pathway.
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Affiliation(s)
- Ye Tang
- State Key Laboratory of Plant Genomics, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Zhennan Zhang
- State Key Laboratory of Plant Genomics, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Zhiyuan Yang
- State Key Laboratory of Plant Genomics, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Jiahe Wu
- State Key Laboratory of Plant Genomics, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
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2
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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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Hu Y, Lehrach H, Janitz M. Comparative analysis of an experimental subcellular protein localization assay and in silico prediction methods. J Mol Histol 2009; 40:343-52. [PMID: 20033263 PMCID: PMC2834777 DOI: 10.1007/s10735-009-9247-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2009] [Accepted: 12/01/2009] [Indexed: 12/12/2022]
Abstract
The subcellular localization of a protein can provide important information about its function within the cell. As eukaryotic cells and particularly mammalian cells are characterized by a high degree of compartmentalization, most protein activities can be assigned to particular cellular compartments. The categorization of proteins by their subcellular localization is therefore one of the essential goals of the functional annotation of the human genome. We previously performed a subcellular localization screen of 52 proteins encoded on human chromosome 21. In the current study, we compared the experimental localization data to the in silico results generated by nine leading software packages with different prediction resolutions. The comparison revealed striking differences between the programs in the accuracy of their subcellular protein localization predictions. Our results strongly suggest that the recently developed predictors utilizing multiple prediction methods tend to provide significantly better performance over purely sequence-based or homology-based predictions.
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Affiliation(s)
- Yuhui Hu
- Department of Vertebrate Genomics, Max Planck Institute for Molecular Genetics, Ihnestr. 73, 14195 Berlin, Germany
- Max Delbrück Center for Molecular Medicine (MDC) in der Helmholtz-Gemeinschaft, The Berlin Institute for Medical Systems Biology, 13125 Berlin-Buch, Germany
| | - Hans Lehrach
- Department of Vertebrate Genomics, Max Planck Institute for Molecular Genetics, Ihnestr. 73, 14195 Berlin, Germany
| | - Michal Janitz
- Department of Vertebrate Genomics, Max Planck Institute for Molecular Genetics, Ihnestr. 73, 14195 Berlin, Germany
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW 2052 Australia
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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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Ream W. Agrobacterium tumefaciens and A. rhizogenes use different proteins to transport bacterial DNA into the plant cell nucleus. Microb Biotechnol 2009; 2:416-27. [PMID: 21255274 PMCID: PMC3815903 DOI: 10.1111/j.1751-7915.2009.00104.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Agrobacterium tumefaciens and A. rhizogenes transport single‐stranded DNA (ssDNA; T‐strands) and virulence proteins into plant cells through a type IV secretion system. DNA transfer initiates when VirD2 nicks border sequences in the tumour‐inducing plasmid, attaches to the 5′ end, and pilots T‐strands into plant cells. Agrobacterium tumefaciens translocates ssDNA‐binding protein VirE2 into plant cells where it targets T‐strands into the nucleus. Some A. rhizogenes strains lack VirE2 but transfer T‐strands efficiently due to the GALLS gene, which complements an A. tumefaciens virE2 mutant. VirE2 and full‐length GALLS (GALLS‐FL) contain nuclear localization sequences that target these proteins to the plant cell nucleus. VirE2 binds cooperatively to T‐strands allowing it to move ssDNA without ATP hydrolysis. Unlike VirE2, GALLS‐FL contains ATP‐binding and helicase motifs similar to those in TraA, a strand transferase involved in conjugation. VirE2 may accumulate in the nucleus and pull T‐strands into the nucleus using the force generated by cooperative DNA binding. GALLS‐FL accumulates inside the nucleus where its predicted ATP‐dependent strand transferase may pull T‐strands into the nucleus. These different mechanisms for nuclear import of T‐strands may affect the efficiency and quality of transgenic events in plant biotechnology applications.
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Affiliation(s)
- Walt Ream
- Department of Microbiology, Oregon State University, Corvallis, OR 97331, USA.
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Zaltsman A, Yi BY, Krichevsky A, Gafni Y, Citovsky V. Yeast-plant coupled vector system for identification of nuclear proteins. PLANT PHYSIOLOGY 2007; 145:1264-71. [PMID: 17704231 PMCID: PMC2151716 DOI: 10.1104/pp.107.105973] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Nuclear proteins are involved in many critical biological processes within plant cells and, therefore, are in the focus of studies that usually begin with demonstrating that the protein of interest indeed exhibits nuclear localization. Thus, studies of plant nuclear proteins would be facilitated by a convenient experimental system for identification of proteins that are actively imported into the cell nucleus and visualization of their nuclear accumulation in vivo. To this end, we developed a system of vectors that allows screening for cDNAs coding for nuclear proteins in a simple genetic assay in yeast cells, and verification of nuclear accumulation in planta following one-step transfer and autofluorescent tagging of the identified clones into a multiple cloning site-compatible and reading frame-compatible plant expression vector. In a recommended third experimental step, the plant expression cassette containing the identified clone can be transferred, also by a one-step cloning, into a binary multigene expression vector for transient or stable coexpression with any other proteins.
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Affiliation(s)
- Adi Zaltsman
- Department of Biochemistry and Cell Biology, State University of New York, Stony Brook, New York 11794-5215, USA
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7
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Abstract
The nicking of the origin of transfer (oriT) is an essential initial step in the conjugative mobilization of plasmid DNA. In the case of staphylococcal plasmid pC221, nicking by the plasmid-specific MobA relaxase is facilitated by the DNA-binding accessory protein MobC; however, the role of MobC in this process is currently unknown. In this study, the site of MobC binding was determined by DNase I footprinting. MobC interacts with oriT DNA at two directly repeated 9 bp sequences, mcb1 and mcb2, upstream of the oriT nic site, and additionally at a third, degenerate repeat within the mobC gene, mcb3. The binding activity of the conserved sequences was confirmed indirectly by competitive electrophoretic mobility shift assays and directly by Surface Plasmon Resonance studies. Mutation at mcb2 abolished detectable nicking activity, suggesting that binding of this site by MobC is a prerequisite for nicking by MobA. Sequential site-directed mutagenesis of each binding site in pC221 has demonstrated that all three are required for mobilization. The MobA relaxase, while unable to bind to oriT DNA alone, was found to associate with a MobC–oriT complex and alter the MobC binding profile in a region between mcb2 and the nic site. Mutagenesis of oriT in this region defines a 7 bp sequence, sra, which was essential for nicking by MobA. Exchange of four divergent bases between the sra of pC221 and the related plasmid pC223 was sufficient to swap their substrate identity in a MobA-specific nicking assay. Based on these observations we propose a model of layered specificity in the assembly of pC221-family relaxosomes, whereby a common MobC:mcb complex presents the oriT substrate, which is then nicked only by the cognate MobA.
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Silby MW, Ferguson GC, Billington C, Heinemann JA. Localization of the plasmid-encoded proteins TraI and MobA in eukaryotic cells. Plasmid 2007; 57:118-30. [PMID: 17084894 DOI: 10.1016/j.plasmid.2006.08.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2006] [Revised: 08/24/2006] [Accepted: 08/30/2006] [Indexed: 12/25/2022]
Abstract
Conjugation mediates gene transfer not only between bacterial species but also from bacteria to yeast, plant, and animal cells. DNA transferred by conjugative plasmids from bacteria to eukaryotes must traverse subcellular membranes in the recipient before the transferred genes can be expressed and inherited. This process is most likely facilitated by putative DNA pilot proteins such as VirD2 of the Agrobacterium tumefaciens Ti plasmid. Here, we test this model as a general feature of trans-kingdom conjugation using the DNA-relaxases TraI and MobA of the IncP and IncQ groups. TraI localized unambiguously and uniformly to the nuclei of both yeast and human cells, whereas MobA displayed a range of subcellular localization patterns. The tendency to localize to the nucleus was not correlated with predicted nuclear localization sequence motifs in either protein, suggesting a lack of stringent requirements for nuclear localizing potential in pilot proteins mediating conjugative DNA transfer to eukaryotes. Further, our results indicate that nuclear localization ability may be more commonly associated with conjugative pilot proteins than previously recognized.
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Affiliation(s)
- Mark W Silby
- Centre for Integrated Research in Biosafety, School of Biological Sciences, University of Canterbury, Private Bag 4800, Christchurch, New Zealand
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Hwang HH, Mysore KS, Gelvin SB. Transgenic Arabidopsis plants expressing Agrobacterium tumefaciens VirD2 protein are less susceptible to Agrobacterium transformation. MOLECULAR PLANT PATHOLOGY 2006; 7:473-484. [PMID: 20507462 DOI: 10.1111/j.1364-3703.2006.00353.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
SUMMARY Agrobacterium tumefaciens causes crown gall disease on many plant species and can result in considerable economic losses. Here we report a new strategy to control crown gall disease by over-expressing Agrobacterium tumefaciens VirD2 protein in plants. Transgenic Arabidopsis plants over-expressing virD2 from constitutive or wound-inducible promoters are less susceptible to Agrobacterium-mediated transformation. Additionally, the transient introduction of an A. tumefaciens virD2 gene in tobacco BY-2 cells reduces subsequent Agrobacterium-mediated transformation.
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Affiliation(s)
- Hau-Hsuan Hwang
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA
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Lacroix B, Li J, Tzfira T, Citovsky V. Will you let me use your nucleus? How Agrobacterium gets its T-DNA expressed in the host plant cell. Can J Physiol Pharmacol 2006; 84:333-45. [PMID: 16902581 DOI: 10.1139/y05-108] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Agrobacterium is the only known bacterium capable of natural DNA transfer into a eukaryotic host. The genes transferred to host plants are contained on a T-DNA (transferred DNA) molecule, the transfer of which begins with its translocation, along with several effector proteins, from the bacterial cell to the host-cell cytoplasm. In the host cytoplasm, the T-complex is formed from a single-stranded copy of the T-DNA (T-strand) associated with several bacterial and host proteins and it is imported into the host nucleus via interactions with the host nuclear import machinery. Once inside the nucleus, the T-complex is most likely directed to the host genome by associating with histones. Finally, the chromatin-associated T-complex is uncoated from its escorting proteins prior to the conversion of the T-strand to a double-stranded form and its integration into the host genome.
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Affiliation(s)
- Benoît Lacroix
- Department of Biochemistry and Cell Biology, State University of NY, Stony Brook, 11794-5212, USA.
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11
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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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12
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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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13
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Goodin MM, Dietzgen RG, Schichnes D, Ruzin S, Jackson AO. pGD vectors: versatile tools for the expression of green and red fluorescent protein fusions in agroinfiltrated plant leaves. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2002; 31:375-83. [PMID: 12164816 DOI: 10.1046/j.1365-313x.2002.01360.x] [Citation(s) in RCA: 301] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
We have constructed a matched set of binary vectors designated pGD, pGDG and pGDR for the expression and co-localization of native proteins and GFP or DsRed fusions in large numbers of plant cells. The utility of these vectors following agroinfiltration into leaves has been demonstrated with four genes from Sonchus yellow net virus, a plant nucleorhabdovirus, and with a nucleolar marker protein. Of the three SYNV proteins tested, sc4 gave identical localization patterns at the cell wall and nucleus when fused to GFP or DsRed. However, some differences in expression patterns were observed depending on whether DsRed or GFP was the fusion partner. In this regard, the DsRed:P fusion showed a similar pattern of localization to GFP:P, but localized foci appeared in the nucleus and near the periphery of the nucleus. Nevertheless, the viral nucleocapsid protein, expressed as a GFP:N fusion, co-localized with DsRed:P in a subnuclear locale in agreement with our previous observations (Goodin et al., 2001). This locale appears to be distinct from the nucleolus as indicated by co-expression of the N protein, DsRed:P and a nucleolar marker AtFib1 fused to GFP. The SYNV M protein, which is believed to be particularly prone to oligomerization, was detectable only as a GFP fusion. Our results indicate that agroinfiltration with bacteria containing the pGD vectors is extremely useful for transient expression of several proteins in a high proportion of the cells of Nicotiana benthamiana leaves. The GFP and DsRed elements incorporated into the pGD system should greatly increase the ease of visualizing co-localization and interactions of proteins in a variety of experimental dicotyledonous hosts.
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Affiliation(s)
- Michael M Goodin
- Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720, USA
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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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15
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Goodin MM, Austin J, Tobias R, Fujita M, Morales C, Jackson AO. Interactions and nuclear import of the N and P proteins of sonchus yellow net virus, a plant nucleorhabdovirus. J Virol 2001; 75:9393-406. [PMID: 11533202 PMCID: PMC114507 DOI: 10.1128/jvi.75.19.9393-9406.2001] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2001] [Accepted: 06/21/2001] [Indexed: 11/20/2022] Open
Abstract
We have characterized the interaction and nuclear localization of the nucleocapsid (N) protein and phosphoprotein (P) of sonchus yellow net nucleorhabdovirus. Expression studies with plant and yeast cells revealed that both N and P are capable of independent nuclear import. Site-specific mutagenesis and deletion analyses demonstrated that N contains a carboxy-terminal bipartite nuclear localization signal (NLS) located between amino acids 465 and 481 and that P contains a karyophillic region between amino acids 40 and 124. The N NLS was fully capable of functioning outside of the context of the N protein and was able to direct the nuclear import of a synthetic protein fusion consisting of green fluorescent protein fused to glutathione S-transferase (GST). Expression and mapping studies suggested that the karyophillic domain in P is located within the N-binding domain. Coexpression of N and P drastically affected their localization patterns relative to those of individually expressed proteins and resulted in a shift of both proteins to a subnuclear region. Yeast two-hybrid and GST pulldown experiments verified the N-P and P-P interactions, and deletion analyses have identified the N and P interacting domains. N NLS mutants were not transported to the nucleus by import-competent P, presumably because N binding masks the P NLS. Taken together, our results support a model for independent entry of N and P into the nucleus followed by associations that mediate subnuclear localization.
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Affiliation(s)
- M M Goodin
- Department of Plant and Microbial Biology, University of California, Berkeley, 94720, USA
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16
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Tzfira T, Rhee Y, Chen MH, Kunik T, Citovsky V. Nucleic acid transport in plant-microbe interactions: the molecules that walk through the walls. Annu Rev Microbiol 2001; 54:187-219. [PMID: 11018128 DOI: 10.1146/annurev.micro.54.1.187] [Citation(s) in RCA: 126] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Many microbes "genetically invade" plants by introducing DNA or RNA molecules into the host cells. For example, plant viruses transport their genomes between host cells, whereas Agrobacterium spp. transfer T-DNA to the cell nucleus and integrate it into the plant DNA. During these events, the transported nucleic acids must negotiate several barriers, such as plant cell walls, plasma membranes, and nuclear envelopes. This review describes the microbial and host proteins that participate in cell-to-cell transport and nuclear import of nucleic acids during infection by plant viruses and Agrobacterium spp. Possible molecular mechanisms by which these transport processes occur are discussed.
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Affiliation(s)
- T Tzfira
- Department of Biochemistry and Cell Biology, State University of New York, Stony Brook, New York 11794-5215, USA
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17
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Affiliation(s)
- D V Ward
- Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720, USA
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18
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Stacey MG, Kopp OR, Kim TH, von Arnim AG. Modular domain structure of Arabidopsis COP1. Reconstitution of activity by fragment complementation and mutational analysis of a nuclear localization signal in planta. PLANT PHYSIOLOGY 2000; 124:979-90. [PMID: 11080276 PMCID: PMC59198 DOI: 10.1104/pp.124.3.979] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2000] [Accepted: 06/08/2000] [Indexed: 05/21/2023]
Abstract
The Arabidopsis COP1 protein functions as a developmental regulator, in part by repressing photomorphogenesis in darkness. Using complementation of a cop1 loss-of-function allele with transgenes expressing fusions of cop1 mutant proteins and beta-glucuronidase, it was confirmed that COP1 consists of two modules, an amino terminal module conferring a basal function during development and a carboxyl terminal module conferring repression of photomorphogenesis. The amino-terminal zinc-binding domain of COP1 was indispensable for COP1 function. In contrast, the debilitating effects of site-directed mutations in the single nuclear localization signal of COP1 were partially compensated by high-level transgene expression. The carboxyl-terminal module of COP1, though unable to substantially ameliorate a cop1 loss-of-function allele on its own, was sufficient for conferring a light-quality-dependent hyperetiolation phenotype in the presence of wild-type COP1. Moreover, partial COP1 activity could be reconstituted in vivo from two non-covalently linked, complementary polypeptides that represent the two functional modules of COP1. Evidence is presented for efficient association of the two sub-fragments of the split COP1 protein in Arabidopsis and in a yeast two-hybrid assay.
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Affiliation(s)
- M G Stacey
- Department of Botany, The University of Tennessee, Knoxville, Tennessee 37996-1100, USA
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19
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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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De Buck S, Jacobs A, Van Montagu M, Depicker A. The DNA sequences of T-DNA junctions suggest that complex T-DNA loci are formed by a recombination process resembling T-DNA integration. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 1999; 20:295-304. [PMID: 10571890 DOI: 10.1046/j.1365-313x.1999.t01-1-00602.x] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
After Agrobacterium-mediated plant transformation, multiple T-DNAs frequently integrate at the same position in the plant genome, resulting in the formation of inverted and direct repeats. Because these inverted repeats cannot be amplified and analyzed by PCR, Arabidopsis root cells were co-transformed with two different T-DNAs with distinct sequences adjacent to the T-DNA borders. Nine direct or inverted T-DNA border junctions were analyzed at the sequence level. Precise end-to-end fusions were found between two right border ends, whereas imprecise fusions and filler DNA were present in T-DNA linkages containing a left border end. The results suggest that end-to-end ligation of double-stranded T-DNAs occurs especially between right T-DNA ends and that illegitimate recombination on the basis of microhomology, deletions, repair activities and insertions of filler DNA is involved in the formation of left border T-DNA junctions. Therefore, a similar illegitimate recombination mechanism is proposed that is involved in the formation of complex T-DNA inserts as well as in the integration of the T-DNA in the plant genome.
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Affiliation(s)
- S De Buck
- Vakgroep Moleculaire Genetica, Department Plantengenetica, Universiteit Gent, Belgium
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Ziemienowicz A, Görlich D, Lanka E, Hohn B, Rossi L. Import of DNA into mammalian nuclei by proteins originating from a plant pathogenic bacterium. Proc Natl Acad Sci U S A 1999; 96:3729-33. [PMID: 10097105 PMCID: PMC22362 DOI: 10.1073/pnas.96.7.3729] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Import of DNA into mammalian nuclei is generally inefficient. Therefore, one of the current challenges in human gene therapy is the development of efficient DNA delivery systems. Here we tested whether bacterial proteins could be used to target DNA to mammalian cells. Agrobacterium tumefaciens, a plant pathogen, efficiently transfers DNA as a nucleoprotein complex to plant cells. Agrobacterium-mediated T-DNA transfer to plant cells is the only known example for interkingdom DNA transfer and is widely used for plant transformation. Agrobacterium virulence proteins VirD2 and VirE2 perform important functions in this process. We reconstituted complexes consisting of the bacterial virulence proteins VirD2, VirE2, and single-stranded DNA (ssDNA) in vitro. These complexes were tested for import into HeLa cell nuclei. Import of ssDNA required both VirD2 and VirE2 proteins. A VirD2 mutant lacking its C-terminal nuclear localization signal was deficient in import of the ssDNA-protein complexes into nuclei. Import of VirD2-ssDNA-VirE2 complexes was fast and efficient, and was shown to depended on importin alpha, Ran, and an energy source. We report here that the bacterium-derived and plant-adapted protein-DNA complex, made in vitro, can be efficiently imported into mammalian nuclei following the classical importin-dependent nuclear import pathway. This demonstrates the potential of our approach to enhance gene transfer to animal cells.
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Affiliation(s)
- A Ziemienowicz
- Friedrich Miescher-Institut, P.O. Box 2543, CH-4002 Basel, Switzerland
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