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Huang FC, Chi SF, Chien PR, Liu YT, Chang HN, Lin CS, Hwang HH. Arabidopsis RAB8A, RAB8B and RAB8D Proteins Interact with Several RTNLB Proteins and are Involved in the Agrobacterium tumefaciens Infection Process. PLANT & CELL PHYSIOLOGY 2021; 62:1572-1588. [PMID: 34255832 DOI: 10.1093/pcp/pcab112] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Revised: 07/01/2021] [Accepted: 07/13/2021] [Indexed: 06/13/2023]
Abstract
Arabidopsis thaliana small GTP-binding proteins, AtRAB8s, associate with the endomembrane system and modulate tubulovesicular trafficking between compartments of the biosynthetic and endocytic pathways. There are five members in Arabidopsis, namely AtRAB8A-8E. Yeast two-hybrid assays, bimolecular fluorescence complementation assays and glutathione-S-transferase pull-down assays showed that RAB8A, 8B and 8D interacted with several membrane-associated reticulon-like (AtRTNLB) proteins in yeast, plant cells and in vitro. Furthermore, RAB8A, 8B and 8D proteins showed interactions with the Agrobacterium tumefaciens virulence protein, VirB2, a component of a type IV secretion system (T4SS). A. tumefaciens uses a T4SS to transfer T-DNA and Virulence proteins to plants, which causes crown gall disease in plants. The Arabidopsis rab8A, rab8B and rab8D single mutants showed decreased levels of Agrobacterium-mediated root and seedling transformation, while the RAB8A, 8B and 8D overexpression transgenic Arabidopsis plants were hypersusceptible to A. tumefaciens and Pseudomonas syringae infections. RAB8A-8E transcripts accumulated differently in roots, rosette leaves, cauline leaves, inflorescence and flowers of wild-type plants. In summary, RAB8A, 8B and 8D interacted with several RTNLB proteins and participated in A. tumefaciens and P. syringae infection processes.
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Affiliation(s)
- Fan-Chen Huang
- Department of Life Sciences, National Chung Hsing University, Taichung 402, Taiwan
| | - Shin-Fei Chi
- Department of Life Sciences, National Chung Hsing University, Taichung 402, Taiwan
| | - Pei-Ru Chien
- Department of Life Sciences, National Chung Hsing University, Taichung 402, Taiwan
| | - Yin-Tzu Liu
- Department of Life Sciences, National Chung Hsing University, Taichung 402, Taiwan
| | - Hsin-Nung Chang
- Department of Life Sciences, National Chung Hsing University, Taichung 402, Taiwan
| | - Choun-Sea Lin
- Agricultural Biotechnology Research Center, Academia Sinica, Taipei 115, Taiwan
| | - Hau-Hsuan Hwang
- Department of Life Sciences, National Chung Hsing University, Taichung 402, Taiwan
- Innovation and Development Center of Sustainable Agriculture, National Chung Hsing University, Taichung 402, Taiwan
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Ramkumar TR, Lenka SK, Arya SS, Bansal KC. A Short History and Perspectives on Plant Genetic Transformation. METHODS IN MOLECULAR BIOLOGY (CLIFTON, N.J.) 2020; 2124:39-68. [PMID: 32277448 DOI: 10.1007/978-1-0716-0356-7_3] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Plant genetic transformation is an important technological advancement in modern science, which has not only facilitated gaining fundamental insights into plant biology but also started a new era in crop improvement and commercial farming. However, for many crop plants, efficient transformation and regeneration still remain a challenge even after more than 30 years of technical developments in this field. Recently, FokI endonuclease-based genome editing applications in plants offered an exciting avenue for augmenting crop productivity but it is mainly dependent on efficient genetic transformation and regeneration, which is a major roadblock for implementing genome editing technology in plants. In this chapter, we have outlined the major historical developments in plant genetic transformation for developing biotech crops. Overall, this field needs innovations in plant tissue culture methods for simplification of operational steps for enhancing the transformation efficiency. Similarly, discovering genes controlling developmental reprogramming and homologous recombination need considerable attention, followed by understanding their role in enhancing genetic transformation efficiency in plants. Further, there is an urgent need for exploring new and low-cost universal delivery systems for DNA/RNA and protein into plants. The advancements in synthetic biology, novel vector systems for precision genome editing and gene integration could potentially bring revolution in crop-genetic potential enhancement for a sustainable future. Therefore, efficient plant transformation system standardization across species holds the key for translating advances in plant molecular biology to crop improvement.
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Affiliation(s)
- Thakku R Ramkumar
- Agronomy Department, IFAS, University of Florida, Gainesville, FL, USA
| | - Sangram K Lenka
- TERI-Deakin NanoBiotechnology Centre, The Energy and Resources Institute, New Delhi, India
| | - Sagar S Arya
- TERI-Deakin NanoBiotechnology Centre, The Energy and Resources Institute, New Delhi, India
| | - Kailash C Bansal
- TERI-Deakin NanoBiotechnology Centre, The Energy and Resources Institute, New Delhi, India.
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Huang FC, Hwang HH. Arabidopsis RETICULON-LIKE4 (RTNLB4) Protein Participates in Agrobacterium Infection and VirB2 Peptide-Induced Plant Defense Response. Int J Mol Sci 2020; 21:ijms21051722. [PMID: 32138311 PMCID: PMC7084338 DOI: 10.3390/ijms21051722] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Revised: 02/28/2020] [Accepted: 02/29/2020] [Indexed: 12/27/2022] Open
Abstract
Agrobacterium tumefaciens uses the type IV secretion system, which consists of VirB1-B11 and VirD4 proteins, to deliver effectors into plant cells. The effectors manipulate plant proteins to assist in T-DNA transfer, integration, and expression in plant cells. The Arabidopsis reticulon-like (RTNLB) proteins are located in the endoplasmic reticulum and are involved in endomembrane trafficking in plant cells. The rtnlb4 mutants were recalcitrant to A. tumefaciens infection, but overexpression of RTNLB4 in transgenic plants resulted in hypersusceptibility to A. tumefaciens transformation, which suggests the involvement of RTNLB4 in A. tumefaciens infection. The expression of defense-related genes, including FRK1, PR1, WRKY22, and WRKY29, were less induced in RTNLB4 overexpression (O/E) transgenic plants after A. tumefaciens elf18 peptide treatment. Pretreatment with elf18 peptide decreased Agrobacterium-mediated transient expression efficiency more in wild-type seedlings than RTNLB4 O/E transgenic plants, which suggests that the induced defense responses in RTNLB4 O/E transgenic plants might be affected after bacterial elicitor treatments. Similarly, A. tumefaciens VirB2 peptide pretreatment reduced transient T-DNA expression in wild-type seedlings to a greater extent than in RTNLB4 O/E transgenic seedlings. Furthermore, the VirB2 peptides induced FRK1, WRKY22, and WRKY29 gene expression in wild-type seedlings but not efr-1 and bak1 mutants. The induced defense-related gene expression was lower in RTNLB4 O/E transgenic plants than wild-type seedlings after VirB2 peptide treatment. These data suggest that RTNLB4 may participate in elf18 and VirB2 peptide-induced defense responses and may therefore affect the A. tumefaciens infection process.
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Affiliation(s)
- Fan-Chen Huang
- Department of Life Sciences, National Chung Hsing University, Taichung 402, Taiwan;
- Ph.D. Program in Microbial Genomics, National Chung Hsing University and Academia Sinica, Taichung 402, Taiwan
| | - Hau-Hsuan Hwang
- Department of Life Sciences, National Chung Hsing University, Taichung 402, Taiwan;
- Ph.D. Program in Microbial Genomics, National Chung Hsing University and Academia Sinica, Taichung 402, Taiwan
- Innovation and Development Center of Sustainable Agriculture, National Chung Hsing University, Taichung 402, Taiwan
- Correspondence: ; Tel.: +886-4-2284-0416-412
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Gusev Y, Mazilov S, Volokhina I, Chumakov M. Agrobacterial, Single-Stranded DNA-Binding Protein VirE2 and Its Complexes. J Comput Biol 2019; 27:675-682. [PMID: 31486677 DOI: 10.1089/cmb.2019.0243] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
VirE2 from Agrobacterium tumefaciens is a single-stranded (ss) DNA-binding protein involved in delivery of ssT-DNA (single-stranded transfer DNA) from the agrobacterial Ti plasmid into the eukaryotic cell nucleus. The crystallized part of VirE2 was studied by X-ray diffraction, and the noncrystallized parts of the C- (40 amino acid residues [aars]) and N- (111 aars) termini of the protein, which are presumably disordered, were evaluated by computational methods. We did a molecular dynamics simulation of VirE2 without VirE1 and observed no large changes in domain orientation. The interaction of VirE2 with ssDNA and formation of ssDNA-VirE2 complexes in silico were studied. We also used computer-aided methods to design model complexes consisting from two- and four-subunit VirE2 proteins. We examined the implication of disordered sites in formation of two- and four-subunit VirE2 complexes. Formation of VirE2 dimers and tetramers within ssDNA-VirE2 complexes was demonstrated by computational methods. Using the Platinum program, we found that hydrophilic amino acids were predominant on the surface of the four-subunit VirE2 complex.
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Affiliation(s)
- Yury Gusev
- Bioengineering Laboratory, Institute of Biochemistry and Physiology of Plants and Microorganisms, Russian Academy of Sciences, Saratov, Russia
| | - Svyatoslav Mazilov
- Bioengineering Laboratory, Institute of Biochemistry and Physiology of Plants and Microorganisms, Russian Academy of Sciences, Saratov, Russia
| | - Irina Volokhina
- Bioengineering Laboratory, Institute of Biochemistry and Physiology of Plants and Microorganisms, Russian Academy of Sciences, Saratov, Russia
| | - Mikhail Chumakov
- Bioengineering Laboratory, Institute of Biochemistry and Physiology of Plants and Microorganisms, Russian Academy of Sciences, Saratov, Russia
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Roushan MR, de Zeeuw MAM, Hooykaas PJJ, van Heusden GPH. Application of phiLOV2.1 as a fluorescent marker for visualization of Agrobacterium effector protein translocation. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2018; 96:685-699. [PMID: 30098065 DOI: 10.1111/tpj.14060] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2018] [Accepted: 07/31/2018] [Indexed: 06/08/2023]
Abstract
Agrobacterium tumefaciens can genetically transform plants by translocating a piece of oncogenic DNA, called T-DNA, into host cells. Transfer is mediated by a type IV secretion system (T4SS). Besides the T-DNA, which is transferred in a single-stranded form and at its 5' end covalently bound to VirD2, several other effector proteins (VirE2, VirE3, VirD5, and VirF) are translocated into the host cells. The fate and function of the translocated proteins inside the host cell are only partly known. Therefore, several studies were conducted to visualize the translocation of the VirE2 protein. As GFP-tagged effector proteins are unable to pass the T4SS, other approaches like the split GFP system were used, but these require specific transgenic recipient cells expressing the complementary part of GFP. Here, we investigated whether use can be made of the photostable variant of LOV, phiLOV2.1, to visualize effector protein translocation from Agrobacterium to non-transgenic yeast and plant cells. We were able to visualize the translocation of all five effector proteins, both to yeast cells, and to cells in Nicotiana tabacum leaves and Arabidopsis thaliana roots. Clear signals were obtained that are easily distinguishable from the background, even in cases in which by comparison the split GFP system did not generate a signal.
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Affiliation(s)
- Mohammad Reza Roushan
- Department of Molecular and Developmental Genetics, Institute of Biology Leiden, Faculty of Science, Leiden University, Sylviusweg 72, 2333 BE, Leiden, The Netherlands
| | - Milou A M de Zeeuw
- Department of Molecular and Developmental Genetics, Institute of Biology Leiden, Faculty of Science, Leiden University, Sylviusweg 72, 2333 BE, Leiden, The Netherlands
| | - Paul J J Hooykaas
- Department of Molecular and Developmental Genetics, Institute of Biology Leiden, Faculty of Science, Leiden University, Sylviusweg 72, 2333 BE, Leiden, The Netherlands
| | - Gerard Paul H van Heusden
- Department of Molecular and Developmental Genetics, Institute of Biology Leiden, Faculty of Science, Leiden University, Sylviusweg 72, 2333 BE, Leiden, The Netherlands
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Volokhina I, Gusev Y, Mazilov S, Moiseeva Y, Chumakov M. Computer evaluation of VirE2 protein complexes for ssDNA transfer ability. Comput Biol Chem 2017; 68:64-70. [DOI: 10.1016/j.compbiolchem.2017.01.016] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2015] [Revised: 01/23/2017] [Accepted: 01/23/2017] [Indexed: 11/16/2022]
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Ohmine Y, Satoh Y, Kiyokawa K, Yamamoto S, Moriguchi K, Suzuki K. DNA repair genes RAD52 and SRS2, a cell wall synthesis regulator gene SMI1, and the membrane sterol synthesis scaffold gene ERG28 are important in efficient Agrobacterium-mediated yeast transformation with chromosomal T-DNA. BMC Microbiol 2016; 16:58. [PMID: 27038795 PMCID: PMC4818910 DOI: 10.1186/s12866-016-0672-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2015] [Accepted: 03/16/2016] [Indexed: 11/25/2022] Open
Abstract
Background Plant pathogenic Agrobacterium strains can transfer T-DNA regions of their Ti plasmids to a broad range of eukaryotic hosts, including fungi, in vitro. In the recent decade, the yeast Saccharomyces cerevisiae is used as a model host to reveal important host proteins for the Agrobacterium-mediated transformation (AMT). Further investigation is required to understand the fundamental mechanism of AMT, including interaction at the cell surface, to expand the host range, and to develop new tools. In this study, we screened a yeast mutant library for low AMT mutant strains by advantage of a chromosome type T-DNA, which transfer is efficient and independent on integration into host chromosome. Results By the mutant screening, we identified four mutant strains (srs2Δ, rad52Δ, smi1Δ and erg28Δ), which showed considerably low AMT efficiency. Structural analysis of T-DNA product replicons in AMT colonies of mutants lacking each of the two DNA repair genes, SRS2 and RAD52, suggested that the genes act soon after T-DNA entry for modification of the chromosomal T-DNA to stably maintain them as linear replicons and to circularize certain T-DNA simultaneously. The cell wall synthesis regulator SMI1 might have a role in the cell surface interaction between the donor and recipient cells, but the smi1Δ mutant exhibited pleiotropic effect, i.e. low effector protein transport as well as low AMT for the chromosomal T-DNA, but relatively high AMT for integrative T-DNAs. The ergosterol synthesis regulator/enzyme-scaffold gene ERG28 probably contributes by sensing a congested environment, because growth of erg28Δ strain was unaffected by the presence of donor bacterial cells, while the growth of the wild-type and other mutant yeast strains was suppressed by their presence. Conclusions RAD52 and the DNA helicase/anti-recombinase gene SRS2 are necessary to form and maintain artificial chromosomes through the AMT of chromosomal T-DNA. A sterol synthesis scaffold gene ERG28 is important in the high-efficiency AMT, possibly by avoiding congestion. The involvement of the cell wall synthesis regulator SMI1 remains to be elucidated.
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Affiliation(s)
- Yuta Ohmine
- Department of Biological Science, Graduate School of Science, Hiroshima University, Kagamiyama 1-3-1, Higashi-Hiroshima, Hiroshima, 739-8526, Japan
| | - Yukari Satoh
- Department of Biological Science, Graduate School of Science, Hiroshima University, Kagamiyama 1-3-1, Higashi-Hiroshima, Hiroshima, 739-8526, Japan
| | - Kazuya Kiyokawa
- Department of Biological Science, Graduate School of Science, Hiroshima University, Kagamiyama 1-3-1, Higashi-Hiroshima, Hiroshima, 739-8526, Japan
| | - Shinji Yamamoto
- Department of Biological Science, Graduate School of Science, Hiroshima University, Kagamiyama 1-3-1, Higashi-Hiroshima, Hiroshima, 739-8526, Japan
| | - Kazuki Moriguchi
- Department of Biological Science, Graduate School of Science, Hiroshima University, Kagamiyama 1-3-1, Higashi-Hiroshima, Hiroshima, 739-8526, Japan
| | - Katsunori Suzuki
- Department of Biological Science, Graduate School of Science, Hiroshima University, Kagamiyama 1-3-1, Higashi-Hiroshima, Hiroshima, 739-8526, Japan.
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Abstract
The use of artificial microRNAs (amiRNAs) is still a relatively new technique in molecular biology with a wide range of applications in life sciences. Here, we describe the silencing of the CBP80/ABH1 gene in Solanum tuberosum with the use of amiRNA. The CBP80/ABH1 protein is part of the Cap Binding Complex (CBC), which is involved in plant responses to drought stress conditions. Transformed plants with a decreased level of CBP80/ABH1 display increased tolerance to water shortage conditions. We describe how to design amiRNA with the Web MicroRNA Designer platform in detail. Additionally, we explain how to perform all steps of a procedure aiming to obtain transgenic potato plants with the use of designed amiRNA, through callus tissue regeneration and Agrobacterium tumefaciens strain LBA4404 as a transgene carrier.
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Kim S, Zbaida D, Elbaum M, Leh H, Nogues C, Buckle M. Surface plasmon resonance imaging reveals multiple binding modes of Agrobacterium transformation mediator VirE2 to ssDNA. Nucleic Acids Res 2015; 43:6579-86. [PMID: 26044711 PMCID: PMC4513855 DOI: 10.1093/nar/gkv571] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2014] [Accepted: 05/20/2015] [Indexed: 11/20/2022] Open
Abstract
VirE2 is the major secreted protein of Agrobacterium tumefaciens in its genetic transformation of plant hosts. It is co-expressed with a small acidic chaperone VirE1, which prevents VirE2 oligomerization. After secretion into the host cell, VirE2 serves functions similar to a viral capsid in protecting the single-stranded transferred DNA en route to the nucleus. Binding of VirE2 to ssDNA is strongly cooperative and depends moreover on protein–protein interactions. In order to isolate the protein–DNA interactions, imaging surface plasmon resonance (SPRi) studies were conducted using surface-immobilized DNA substrates of length comparable to the protein-binding footprint. Binding curves revealed an important influence of substrate rigidity with a notable preference for poly-T sequences and absence of binding to both poly-A and double-stranded DNA fragments. Dissociation at high salt concentration confirmed the electrostatic nature of the interaction. VirE1–VirE2 heterodimers also bound to ssDNA, though by a different mechanism that was insensitive to high salt. Neither VirE2 nor VirE1–VirE2 followed the Langmuir isotherm expected for reversible monomeric binding. The differences reflect the cooperative self-interactions of VirE2 that are suppressed by VirE1.
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Affiliation(s)
- Sanghyun Kim
- Dept of Materials and Interfaces, Weizmann Institute of Science, 7610001 Rehovot, Israel
| | - David Zbaida
- Dept of Materials and Interfaces, Weizmann Institute of Science, 7610001 Rehovot, Israel
| | - Michael Elbaum
- Dept of Materials and Interfaces, Weizmann Institute of Science, 7610001 Rehovot, Israel
| | - Hervé Leh
- LBPA, Institut d'Alembert, ENS de Cachan, CNRS, 61, avenue du Président Wilson, F-94235 Cachan, France
| | - Claude Nogues
- LBPA, Institut d'Alembert, ENS de Cachan, CNRS, 61, avenue du Président Wilson, F-94235 Cachan, France
| | - Malcolm Buckle
- LBPA, Institut d'Alembert, ENS de Cachan, CNRS, 61, avenue du Président Wilson, F-94235 Cachan, France
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den Dulk-Ras A, Vergunst AC, Hooykaas PJJ. Cre Reporter Assay for Translocation (CRAfT): a tool for the study of protein translocation into host cells. Methods Mol Biol 2014; 1197:103-121. [PMID: 25172277 DOI: 10.1007/978-1-4939-1261-2_6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Many pathogenic bacteria introduce virulence proteins, also called effector proteins, into host cells to accomplish infection. Such effector proteins are often translocated into host cells by bacterial type III (T3SS) or type IV secretion systems (T4SS). To better understand the molecular mechanisms underlying virulence, it is essential to identify the effector proteins and determine their functions. Several reporter assays have been established to identify translocated effector proteins and verify T3SS- or T4SS-dependent transport into host cells. Here we describe a protocol to monitor the translocation of candidate effector proteins using Cre recombinase as a reporter, and more specifically how this Cre Reporter Assay for Translocation (CRAfT) can be used to detect translocation of Vir proteins from Agrobacterium tumefaciens into yeast and plant cells. The assay can be adapted for the study of the T3SS or T4SS of human pathogens.
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Affiliation(s)
- Amke den Dulk-Ras
- Sylvius Laboratory, Institute of Biology Leiden, Leiden University, Sylviusweg 72, Leiden, The Netherlands
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Volokhina I, Gusev Y, Mazilov S, Chumakov M. VirE2-dependent pores for ssDNA transfer across artificial and cell membranes. J Bioinform Comput Biol 2012; 10:1241009. [PMID: 22809344 DOI: 10.1142/s0219720012410090] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The transfer of single-stranded (ss) T-DNA from soil bacteria of the genus Agrobacterium with the help of the VirE2 protein, which possibly mediates the delivery of ss-T-DNA across the cell membrane, was demonstrated earlier, but how VirE2 participates in ssDNA transfer across artificial and natural membranes is not known. Using computational methods, we reconstructed model structures composed of two and four VirE2 proteins and showed by the MOLE program the formation of pores with channel diameters of 1.2-1.6 and 1.4-4.6 nm in a model structure formed from two and four VirE2 molecules, respectively. Using light scattering, we recorded the size distribution for recombinant VirE2-dependent complexes in aqueous solutions and found that VirE2 in a buffer solution is present as a complex made up of two or more proteins. We revealed single, long-lived jumps in voltage-dependent membrane conductance during coincubation of planar black membranes with the VirE2 protein. On the addition of VirE2 and FAM-labeled oligonucleotides to HeLa cells, the fluorescence intensity for the cells increased by 56% as compared to that for cells incubated only with oligonucleotides.
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Affiliation(s)
- Irina Volokhina
- Institute of Biochemistry and Physiology of Plants and Microorganisms, Russian Academy of Sciences, 13 Prospekt Entuziastov, Saratov 410049, Russia
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Anand A, Rojas CM, Tang Y, Mysore KS. Several components of SKP1/Cullin/F-box E3 ubiquitin ligase complex and associated factors play a role in Agrobacterium-mediated plant transformation. THE NEW PHYTOLOGIST 2012; 195:203-16. [PMID: 22486382 DOI: 10.1111/j.1469-8137.2012.04133.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
• Successful genetic transformation of plants by Agrobacterium tumefaciens requires the import of bacterial T-DNA and virulence proteins into the plant cell that eventually form a complex (T-complex). The essential components of the T-complex include the single stranded T-DNA, bacterial virulence proteins (VirD2, VirE2, VirE3 and VirF) and associated host proteins that facilitate the transfer and integration of T-DNA. The removal of the proteins from the T-complex is likely achieved by targeted proteolysis mediated by VirF and the plant ubiquitin proteasome complex. • We evaluated the involvement of the host SKP1/culin/F-box (SCF)-E3 ligase complex and its role in plant transformation. Gene silencing, mutant screening and gene expression studies suggested that the Arabidopsis homologs of yeast SKP1 (suppressor of kinetochore protein 1) protein, ASK1 and ASK2, are required for Agrobacterium-mediated plant transformation. • We identified the role for SGT1b (suppressor of the G2 allele of SKP1), an accessory protein that associates with SCF-complex, in plant transformation. We also report the differential expression of many genes that encode F-box motif containing SKP1-interacting proteins (SKIP) upon Agrobacterium infection. • We speculate that these SKIP genes could encode the plant specific F-box proteins that target the T-complex associated proteins for polyubiquitination and subsequent degradation by the 26S proteasome.
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Affiliation(s)
- Ajith Anand
- Plant Biology Division, The Samuel Roberts Noble Foundation, Ardmore, OK 73402, USA
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Gelvin SB. Traversing the Cell: Agrobacterium T-DNA's Journey to the Host Genome. FRONTIERS IN PLANT SCIENCE 2012; 3:52. [PMID: 22645590 PMCID: PMC3355731 DOI: 10.3389/fpls.2012.00052] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2012] [Accepted: 02/28/2012] [Indexed: 05/05/2023]
Abstract
The genus Agrobacterium is unique in its ability to conduct interkingdom genetic exchange. Virulent Agrobacterium strains transfer single-strand forms of T-DNA (T-strands) and several Virulence effector proteins through a bacterial type IV secretion system into plant host cells. T-strands must traverse the plant wall and plasma membrane, traffic through the cytoplasm, enter the nucleus, and ultimately target host chromatin for stable integration. Because any DNA sequence placed between T-DNA "borders" can be transferred to plants and integrated into the plant genome, the transfer and intracellular trafficking processes must be mediated by bacterial and host proteins that form complexes with T-strands. This review summarizes current knowledge of proteins that interact with T-strands in the plant cell, and discusses several models of T-complex (T-strand and associated proteins) trafficking. A detailed understanding of how these macromolecular complexes enter the host cell and traverse the plant cytoplasm will require development of novel technologies to follow molecules from their bacterial site of synthesis into the plant cell, and how these transferred molecules interact with host proteins and sub-cellular structures within the host cytoplasm and nucleus.
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Affiliation(s)
- Stanton B. Gelvin
- Department of Biological Sciences, Purdue UniversityWest Lafayette, IN, USA
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Volokhina IV, Gusev YS, Mazilov SI, Chumakov MI. Supramolecular complexes of the Agrobacterium tumefaciens virulence protein VirE2. BIOCHEMISTRY (MOSCOW) 2011; 76:1270-5. [DOI: 10.1134/s0006297911110095] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Conjugative DNA transfer into human cells by the VirB/VirD4 type IV secretion system of the bacterial pathogen Bartonella henselae. Proc Natl Acad Sci U S A 2011; 108:14643-8. [PMID: 21844337 DOI: 10.1073/pnas.1019074108] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Bacterial type IV secretion systems (T4SS) mediate interbacterial conjugative DNA transfer and transkingdom protein transfer into eukaryotic host cells in bacterial pathogenesis. The sole bacterium known to naturally transfer DNA into eukaryotic host cells via a T4SS is the plant pathogen Agrobacterium tumefaciens. Here we demonstrate T4SS-mediated DNA transfer from a human bacterial pathogen into human cells. We show that the zoonotic pathogen Bartonella henselae can transfer a cryptic plasmid occurring in the bartonellae into the human endothelial cell line EA.hy926 via its T4SS VirB/VirD4. DNA transfer into EA.hy926 cells was demonstrated by using a reporter derivative of this Bartonella-specific mobilizable plasmid generated by insertion of a eukaryotic egfp-expression cassette. Fusion of the C-terminal secretion signal of the endogenous VirB/VirD4 protein substrate BepD with the plasmid-encoded DNA-transport protein Mob resulted in a 100-fold increased DNA transfer rate. Expression of the delivered egfp gene in EA.hy926 cells required cell division, suggesting that nuclear envelope breakdown may facilitate passive entry of the transferred ssDNA into the nucleus as prerequisite for complementary strand synthesis and transcription of the egfp gene. Addition of an eukaryotic neomycin phosphotransferase expression cassette to the reporter plasmid facilitated selection of stable transgenic EA.hy926 cell lines that display chromosomal integration of the transferred plasmid DNA. Our data suggest that T4SS-dependent DNA transfer into host cells may occur naturally during human infection with Bartonella and that these chronically infecting pathogens have potential for the engineering of in vivo gene-delivery vectors with applications in DNA vaccination and therapeutic gene therapy.
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Chumakov MI, Mazilov SI, Gusev YS, Volokhina IV. Study of the ability of Agrobacterial protein VirE2 to form pores in membranes. BIOCHEMISTRY MOSCOW SUPPLEMENT SERIES A-MEMBRANE AND CELL BIOLOGY 2010. [DOI: 10.1134/s1990747810040057] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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17
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Gelvin SB. Finding a way to the nucleus. Curr Opin Microbiol 2009; 13:53-8. [PMID: 20022799 DOI: 10.1016/j.mib.2009.11.003] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2009] [Revised: 11/17/2009] [Accepted: 11/24/2009] [Indexed: 11/17/2022]
Abstract
Agrobacterium species transfer single-strand DNA and virulence effector proteins to plants. To understand how Agrobacterium achieves interkingdom horizontal gene transfer, scientists have investigated how the interaction of bacterial effector proteins with host proteins directs T-DNA to the plant nucleus. VirE2, a single-strand DNA binding protein, likely plays a key role in T-DNA nuclear targeting. However, subcellular trafficking of VirE2 remains controversial, with reports of both cytoplasmic and nuclear localization. The recent discovery that phosphorylation of the VirE2 interacting protein VIP1 modulates both nuclear targeting and transformation may provide a solution to this conundrum. Novel experimental systems that allow tracking of VirE2 as it exits Agrobacterium and enters the plant cell will also aid in understanding virulence protein/T-DNA cytoplasmic trafficking.
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Affiliation(s)
- Stanton B Gelvin
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA.
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18
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Tenea GN, Spantzel J, Lee LY, Zhu Y, Lin K, Johnson SJ, Gelvin SB. Overexpression of several Arabidopsis histone genes increases agrobacterium-mediated transformation and transgene expression in plants. THE PLANT CELL 2009; 21:3350-67. [PMID: 19820187 PMCID: PMC2782275 DOI: 10.1105/tpc.109.070607] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2009] [Revised: 08/10/2009] [Accepted: 09/25/2009] [Indexed: 05/18/2023]
Abstract
The Arabidopsis thaliana histone H2A-1 is important for Agrobacterium tumefaciens-mediated plant transformation. Mutation of HTA1, the gene encoding histone H2A-1, results in decreased T-DNA integration into the genome of Arabidopsis roots, whereas overexpression of HTA1 increases transformation frequency. To understand the mechanism by which HTA1 enhances transformation, we investigated the effects of overexpression of numerous Arabidopsis histones on transformation and transgene expression. Transgenic Arabidopsis containing cDNAs encoding histone H2A (HTA), histone H4 (HFO), and histone H3-11 (HTR11) displayed increased transformation susceptibility, whereas histone H2B (HTB) and most histone H3 (HTR) cDNAs did not increase transformation. A parallel increase in transient gene expression was observed when histone HTA, HFO, or HTR11 overexpression constructs were cotransfected with double- or single-stranded forms of a gusA gene into tobacco (Nicotiana tabacum) protoplasts. However, these cDNAs did not increase expression of a previously integrated transgene. We identified the N-terminal 39 amino acids of H2A-1 as sufficient to increase transient transgene expression in plants. After transfection, transgene DNA accumulates more rapidly in the presence of HTA1 than with a control construction. Our results suggest that certain histones enhance transgene expression, protect incoming transgene DNA during the initial stages of transformation, and subsequently increase the efficiency of Agrobacterium-mediated transformation.
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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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20
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Gillespie JJ, Ammerman NC, Dreher-Lesnick SM, Rahman MS, Worley MJ, Setubal JC, Sobral BS, Azad AF. An anomalous type IV secretion system in Rickettsia is evolutionarily conserved. PLoS One 2009; 4:e4833. [PMID: 19279686 PMCID: PMC2653234 DOI: 10.1371/journal.pone.0004833] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2009] [Accepted: 01/28/2009] [Indexed: 01/06/2023] Open
Abstract
BACKGROUND Bacterial type IV secretion systems (T4SSs) comprise a diverse transporter family functioning in conjugation, competence, and effector molecule (DNA and/or protein) translocation. Thirteen genome sequences from Rickettsia, obligate intracellular symbionts/pathogens of a wide range of eukaryotes, have revealed a reduced T4SS relative to the Agrobacterium tumefaciens archetype (vir). However, the Rickettsia T4SS has not been functionally characterized for its role in symbiosis/virulence, and none of its substrates are known. RESULTS Superimposition of T4SS structural/functional information over previously identified Rickettsia components implicate a functional Rickettsia T4SS. virB4, virB8 and virB9 are duplicated, yet only one copy of each has the conserved features of similar genes in other T4SSs. An extraordinarily duplicated VirB6 gene encodes five hydrophobic proteins conserved only in a short region known to be involved in DNA transfer in A. tumefaciens. virB1, virB2 and virB7 are newly identified, revealing a Rickettsia T4SS lacking only virB5 relative to the vir archetype. Phylogeny estimation suggests vertical inheritance of all components, despite gene rearrangements into an archipelago of five islets. Similarities of Rickettsia VirB7/VirB9 to ComB7/ComB9 proteins of epsilon-proteobacteria, as well as phylogenetic affinities to the Legionella lvh T4SS, imply the Rickettsiales ancestor acquired a vir-like locus from distantly related bacteria, perhaps while residing in a protozoan host. Modern modifications of these systems likely reflect diversification with various eukaryotic host cells. CONCLUSION We present the rvh (Rickettsiales vir homolog) T4SS, an evolutionary conserved transporter with an unknown role in rickettsial biology. This work lays the foundation for future laboratory characterization of this system, and also identifies the Legionella lvh T4SS as a suitable genetic model.
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Affiliation(s)
- Joseph J Gillespie
- Virginia Bioinformatics Institute at Virginia Tech, Blacksburg, Virginia, United States of America.
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21
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Bhattacharjee S, Lee LY, Oltmanns H, Cao H, Cuperus J, Gelvin SB. IMPa-4, an Arabidopsis importin alpha isoform, is preferentially involved in agrobacterium-mediated plant transformation. THE PLANT CELL 2008; 20:2661-80. [PMID: 18836040 PMCID: PMC2590722 DOI: 10.1105/tpc.108.060467] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Successful transformation of plants by Agrobacterium tumefaciens requires that the bacterial T-complex actively escorts T-DNA into the host's nucleus. VirD2 and VirE2 are virulence proteins on the T-complex that have plant-functional nuclear localization signal sequences that may recruit importin alpha proteins of the plant for nuclear import. In this study, we evaluated the involvement of seven of the nine members of the Arabidopsis thaliana importin alpha family in Agrobacterium transformation. Yeast two-hybrid, plant bimolecular fluorescence complementation, and in vitro protein-protein interaction assays demonstrated that all tested Arabidopsis importin alpha members can interact with VirD2 and VirE2. However, only disruption of the importin IMPa-4 inhibited transformation and produced the rat (resistant to Agrobacterium transformation) phenotype. Overexpression of six importin alpha members, including IMPa-4, rescued the rat phenotype in the impa-4 mutant background. Roots of wild-type and impa-4 Arabidopsis plants expressing yellow fluorescent protein-VirD2 displayed nuclear localization of the fusion protein, indicating that nuclear import of VirD2 is not affected in the impa-4 mutant. Somewhat surprisingly, VirE2-yellow fluorescent protein mainly localized to the cytoplasm of both wild-type and impa-4 Arabidopsis cells and to the cytoplasm of wild-type tobacco (Nicotiana tabacum) cells. However, bimolecular fluorescence complementation assays indicated that VirE2 could localize to the nucleus when IMPa-4, but not when IMPa-1, was overexpressed.
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Affiliation(s)
- Saikat Bhattacharjee
- Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907, USA
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22
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Grange W, Duckely M, Husale S, Jacob S, Engel A, Hegner M. VirE2: a unique ssDNA-compacting molecular machine. PLoS Biol 2008; 6:e44. [PMID: 18303950 PMCID: PMC2253637 DOI: 10.1371/journal.pbio.0060044] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2007] [Accepted: 01/08/2008] [Indexed: 11/18/2022] Open
Abstract
The translocation of single-stranded DNA (ssDNA) across membranes of two cells is a fundamental biological process occurring in both bacterial conjugation and Agrobacterium pathogenesis. Whereas bacterial conjugation spreads antibiotic resistance, Agrobacterium facilitates efficient interkingdom transfer of ssDNA from its cytoplasm to the host plant cell nucleus. These processes rely on the Type IV secretion system (T4SS), an active multiprotein channel spanning the bacterial inner and outer membranes. T4SSs export specific proteins, among them relaxases, which covalently bind to the 5' end of the translocated ssDNA and mediate ssDNA export. In Agrobacterium tumefaciens, another exported protein-VirE2-enhances ssDNA transfer efficiency 2000-fold. VirE2 binds cooperatively to the transferred ssDNA (T-DNA) and forms a compact helical structure, mediating T-DNA import into the host cell nucleus. We demonstrated-using single-molecule techniques-that by cooperatively binding to ssDNA, VirE2 proteins act as a powerful molecular machine. VirE2 actively pulls ssDNA and is capable of working against 50-pN loads without the need for external energy sources. Combining biochemical and cell biology data, we suggest that, in vivo, VirE2 binding to ssDNA allows an efficient import and pulling of ssDNA into the host. These findings provide a new insight into the ssDNA translocation mechanism from the recipient cell perspective. Efficient translocation only relies on the presence of ssDNA binding proteins in the recipient cell that compacts ssDNA upon binding. This facilitated transfer could hence be a more general ssDNA import mechanism also occurring in bacterial conjugation and DNA uptake processes.
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Affiliation(s)
- Wilfried Grange
- Centre for Research on Adaptive Nanostructures and Nanodevices, Trinity College Dublin, Dublin, Ireland
- National Centre of Competence in Research Nanoscale Science, Institute of Physics, Basel, Switzerland
| | - Myriam Duckely
- M. E. Müller Institute for Structural Biology, Basel, Switzerland
- Novartis AG, Basel, Switzerland
| | - Sudhir Husale
- National Centre of Competence in Research Nanoscale Science, Institute of Physics, Basel, Switzerland
- Rowland Institute at Harvard, Harvard University, Cambridge, Massachusetts, United States of America
| | - Susan Jacob
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
| | - Andreas Engel
- M. E. Müller Institute for Structural Biology, Basel, Switzerland
| | - Martin Hegner
- Centre for Research on Adaptive Nanostructures and Nanodevices, Trinity College Dublin, Dublin, Ireland
- National Centre of Competence in Research Nanoscale Science, Institute of Physics, Basel, Switzerland
- * To whom correspondence should be addressed. E-mail:
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23
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McCullen CA, Binns AN. Agrobacterium tumefaciens and plant cell interactions and activities required for interkingdom macromolecular transfer. Annu Rev Cell Dev Biol 2006; 22:101-27. [PMID: 16709150 DOI: 10.1146/annurev.cellbio.22.011105.102022] [Citation(s) in RCA: 186] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Host recognition and macromolecular transfer of virulence-mediating effectors represent critical steps in the successful transformation of plant cells by Agrobacterium tumefaciens. This review focuses on bacterial and plant-encoded components that interact to mediate these two processes. First, we examine the means by which Agrobacterium recognizes the host, via both diffusible plant-derived chemicals and cell-cell contact, with emphasis on the mechanisms by which multiple host signals are recognized and activate the virulence process. Second, we characterize the recognition and transfer of protein and protein-DNA complexes through the bacterial and plant cell membrane and wall barriers, emphasizing the central role of a type IV secretion system-the VirB complex-in this process.
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Affiliation(s)
- Colleen A McCullen
- Department of Biology and Plant Sciences Institute, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6018, USA
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24
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Krichevsky A, Gutgarts H, Kozlovsky SV, Tzfira T, Sutton A, Sternglanz R, Mandel G, Citovsky V. C2H2 zinc finger-SET histone methyltransferase is a plant-specific chromatin modifier. Dev Biol 2006; 303:259-69. [PMID: 17224141 PMCID: PMC1831845 DOI: 10.1016/j.ydbio.2006.11.012] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2006] [Revised: 10/20/2006] [Accepted: 11/06/2006] [Indexed: 01/29/2023]
Abstract
Histone modification represents a universal mechanism for regulation of eukaryotic gene expression underlying diverse biological processes from neuronal gene expression in mammals to control of flowering in plants. In animal cells, these chromatin modifications are effected by well-defined multiprotein complexes containing specific histone-modifying activities. In plants, information about the composition of such co-repressor complexes is just beginning to emerge. Here, we report that two Arabidopsis thaliana factors, a SWIRM domain polyamine oxidase protein, AtSWP1, and a plant-specific C2H2 zinc finger-SET domain protein, AtCZS, interact with each other in plant cells and repress expression of a negative regulator of flowering, FLOWERING LOCUS C (FLC) via an autonomous, vernalization-independent pathway. Loss-of-function of either AtSWP1 or AtCZS results in reduced dimethylation of lysine 9 and lysine 27 of histone H3 and hyperacetylation of histone H4 within the FLC locus, in elevated FLC mRNA levels, and in moderately delayed flowering. Thus, AtSWP1 and AtCZS represent two main components of a co-repressor complex that fine tunes flowering and is unique to plants.
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Affiliation(s)
- Alexander Krichevsky
- Department of Biochemistry and Cell Biology, State University of New York, Stony Brook, NY 11794-5215, USA.
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25
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Frenkiel-Krispin D, Wolf SG, Albeck S, Unger T, Peleg Y, Jacobovitch J, Michael Y, Daube S, Sharon M, Robinson CV, Svergun DI, Fass D, Tzfira T, Elbaum M. Plant transformation by Agrobacterium tumefaciens: modulation of single-stranded DNA-VirE2 complex assembly by VirE1. J Biol Chem 2006; 282:3458-64. [PMID: 17060320 DOI: 10.1074/jbc.m605270200] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [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 the transfer of DNA. A key factor in this process is the bacterial virulence protein VirE2, which associates stoichiometrically with the transported single-stranded (ss) DNA molecule (T-strand). As observed in vitro by transmission electron microscopy, VirE2-ssDNA readily forms an extended helical complex with a structure well suited to the tasks of DNA protection and nuclear import. Here we have elucidated the role of the specific molecular chaperone VirE1 in regulating VireE2-VirE2 and VirE2-ssDNA interactions. VirE2 alone formed functional filamentous aggregates capable of ssDNA binding. In contrast, co-expression with VirE1 yielded monodisperse VirE1-VirE2 complexes. Cooperative binding of VirE2 to ssDNA released VirE1, resulting in a controlled formation mechanism for the helical complex that is further promoted by macromolecular crowding. Based on this in vitro evidence, we suggest that the constrained volume of the VirB channel provides a natural site for the exchange of VirE2 binding from VirE1 to the T-strand.
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Affiliation(s)
- Daphna Frenkiel-Krispin
- Department of Materials and Interfaces, Weizmann Institute of Science, Rehovot 76100, Israel
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26
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Hodges LD, Vergunst AC, Neal-McKinney J, den Dulk-Ras A, Moyer DM, Hooykaas PJJ, Ream W. Agrobacterium rhizogenes GALLS protein contains domains for ATP binding, nuclear localization, and type IV secretion. J Bacteriol 2006; 188:8222-30. [PMID: 17012398 PMCID: PMC1698208 DOI: 10.1128/jb.00747-06] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Agrobacterium tumefaciens and Agrobacterium rhizogenes are closely related plant pathogens that cause different diseases, crown gall and hairy root. Both diseases result from transfer, integration, and expression of plasmid-encoded bacterial genes located on the transferred DNA (T-DNA) in the plant genome. Bacterial virulence (Vir) proteins necessary for infection are also translocated into plant cells. Transfer of single-stranded DNA (ssDNA) and Vir proteins requires a type IV secretion system, a protein complex spanning the bacterial envelope. A. tumefaciens translocates the ssDNA-binding protein VirE2 into plant cells, where it binds single-stranded T-DNA and helps target it to the nucleus. Although some strains of A. rhizogenes lack VirE2, they are pathogenic and transfer T-DNA efficiently. Instead, these bacteria express the GALLS protein, which is essential for their virulence. The GALLS protein can complement an A. tumefaciens virE2 mutant for tumor formation, indicating that GALLS can substitute for VirE2. Unlike VirE2, GALLS contains ATP-binding and helicase motifs similar to those in TraA, a strand transferase involved in conjugation. Both GALLS and VirE2 contain nuclear localization sequences and a C-terminal type IV secretion signal. Here we show that mutations in any of these domains abolished the ability of GALLS to substitute for VirE2.
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Affiliation(s)
- Larry D Hodges
- Department of Microbiology, Oregon State University, Corvallis, OR 97331, USA
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27
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Lavigne JP, Botella E, O'Callaghan D. [Type IV secretion system and their effectors: an update]. ACTA ACUST UNITED AC 2006; 54:296-303. [PMID: 16473480 DOI: 10.1016/j.patbio.2005.04.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2004] [Accepted: 04/12/2005] [Indexed: 12/26/2022]
Abstract
Subversion of eukaryotic hosts by bacterial pathogens requires specialized macromolecules secretion systems delivering virulence factors either into the environment or directly into host cells. Transport of molecules across bacterial and eukaryotic membranes is a process requiring multi-component machineries called secretion systems. This review focuses on the Type IV secretion system. This complex is required for genetic exchange (DNA transport) and secretion of effectors (proteins, macromolecules, DNA-proteins complex) into target cells. They transport a wide variety of substrates including large DNA/protein complexes, multi protein toxins, or individual proteins. We describe recent advances on the structure and the function of this secretion system, their effectors and their effects on the functions of eukaryotic cell.
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Affiliation(s)
- J-P Lavigne
- Inserm U 431, faculté de médecine, avenue Kennedy, 30908 Nîmes cedex 02, France.
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28
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Haefele T, Kita-Tokarczyk K, Meier W. Phase behavior of mixed Langmuir monolayers from amphiphilic block copolymers and an antimicrobial peptide. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2006; 22:1164-72. [PMID: 16430280 DOI: 10.1021/la0524216] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
The behavior of binary monolayers from PMOXA-PDMS-PMOXA triblock copolymers and alamethicin, an antimicrobial peptide, was investigated in the context of formation of novel biocomposite nanostructured materials. The properties of mixed monolayers were studied by surface pressure-area isotherms and Brewster angle imaging. As reported previously, functionality of alamethicin relies on its aggregation properties in lipid mono- and bilayers. This is also the case in polymer matrixes, however, here the mixing properties differ from lipid-peptide systems due to the polymers' structural specificity. The peptide influence on the polymer films is provided in detail for the first time, and supported by the compressibility data to asses the elastic properties of such composite membranes.
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Affiliation(s)
- Thomas Haefele
- Department of Chemistry, University of Basel, Klingelbergstrasse 80, 4056 Basel, Switzerland
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29
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Christie PJ, Atmakuri K, Krishnamoorthy V, Jakubowski S, Cascales E. Biogenesis, architecture, and function of bacterial type IV secretion systems. Annu Rev Microbiol 2006; 59:451-85. [PMID: 16153176 PMCID: PMC3872966 DOI: 10.1146/annurev.micro.58.030603.123630] [Citation(s) in RCA: 511] [Impact Index Per Article: 28.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Type IV secretion (T4S) systems are ancestrally related to bacterial conjugation machines. These systems assemble as a translocation channel, and often also as a surface filament or protein adhesin, at the envelopes of Gram-negative and Gram-positive bacteria. These organelles mediate the transfer of DNA and protein substrates to phylogenetically diverse prokaryotic and eukaryotic target cells. Many basic features of T4S are known, including structures of machine subunits, steps of machine assembly, substrates and substrate recognition mechanisms, and cellular consequences of substrate translocation. A recent advancement also has enabled definition of the translocation route for a DNA substrate through a T4S system of a Gram-negative bacterium. This review emphasizes the dynamics of assembly and function of model conjugation systems and the Agrobacterium tumefaciens VirB/D4 T4S system. We also summarize salient features of the increasingly studied effector translocator systems of mammalian pathogens.
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Affiliation(s)
- Peter J Christie
- Department of Microbiology and Molecular Genetics, UT-Houston Medical School, Houston, Texas 77030, USA.
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30
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Duckely M, Oomen C, Axthelm F, Van Gelder P, Waksman G, Engel A. The VirE1VirE2 complex ofAgrobacterium tumefaciensinteracts with single-stranded DNA and forms channels. Mol Microbiol 2005; 58:1130-42. [PMID: 16262795 DOI: 10.1111/j.1365-2958.2005.04894.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The VirE2 protein is crucial for the transfer of single-stranded DNA (ssDNA) from Agrobacterium tumefaciens to the nucleus of the plant host cell because of its ssDNA binding activity, assistance in nuclear import and putative ssDNA channel activity. The native form of VirE2 in Agrobacterium's cytoplasm is in complex with its specific chaperone, VirE1. Here, we describe the ability of the VirE1VirE2 complex to both bind ssDNA and form channels. The affinity of the VirE1VirE2 complex for ssDNA is slightly reduced compared with VirE2, but the kinetics of binding to ssDNA are unaffected by the presence of VirE1. Upon binding of VirE1VirE2 to ssDNA, similar helical structures to those reported for the VirE2-ssDNA complex were observed by electron microscopy. The VirE1VirE2 complex can release VirE1 once the VirE2-ssDNA complexes assembled. VirE2 exhibits a low affinity for small unilamellar vesicles composed of bacterial lipids and a high affinity for lipid vesicles containing sterols and sphingolipids, typical components of animal and plant membranes. In contrast, the VirE1VirE2 complex associated similarly with all kind of lipids. Finally, black lipid membrane experiments revealed the ability of the VirE1VirE2 complex to form channels. However, the majority of the channels displayed a conductance that was a third of the conductance of VirE2 channels. Our results demonstrate that the binding of VirE1 to VirE2 does not inhibit VirE2 functions and that the effector-chaperone complex is multifunctional.
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Affiliation(s)
- Myriam Duckely
- M.E. Müller Institute for Structural Biology, Biozentrum, University of Basel, Basel, CH-4056, Switzerland
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31
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Batut J, Andersson SGE, O'Callaghan D. The evolution of chronic infection strategies in the alpha-proteobacteria. Nat Rev Microbiol 2004; 2:933-45. [PMID: 15550939 DOI: 10.1038/nrmicro1044] [Citation(s) in RCA: 143] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Many of the alpha-proteobacteria establish long-term, often chronic, interactions with higher eukaryotes. These interactions range from pericellular colonization through facultative intracellular multiplication to obligate intracellular lifestyles. A common feature in this wide range of interactions is modulation of host-cell proliferation, which sometimes leads to the formation of tumour-like structures in which the bacteria can grow. Comparative genome analyses reveal genome reduction by gene loss in the intracellular alpha-proteobacterial lineages, and genome expansion by gene duplication and horizontal gene transfer in the free-living species. In this review, we discuss alpha-proteobacterial genome evolution and highlight strategies and mechanisms used by these bacteria to infect and multiply in eukaryotic cells.
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Affiliation(s)
- Jacques Batut
- Laboratory of Plant Microbe Interactions, CNRS-INRA, BP27, 31326 Castanet-Tolosan Cedex, France
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32
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Henderson IR, Navarro-Garcia F, Desvaux M, Fernandez RC, Ala'Aldeen D. Type V protein secretion pathway: the autotransporter story. Microbiol Mol Biol Rev 2004; 68:692-744. [PMID: 15590781 PMCID: PMC539010 DOI: 10.1128/mmbr.68.4.692-744.2004] [Citation(s) in RCA: 595] [Impact Index Per Article: 29.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Gram-negative bacteria possess an outer membrane layer which constrains uptake and secretion of solutes and polypeptides. To overcome this barrier, bacteria have developed several systems for protein secretion. The type V secretion pathway encompasses the autotransporter proteins, the two-partner secretion system, and the recently described type Vc or AT-2 family of proteins. Since its discovery in the late 1980s, this family of secreted proteins has expanded continuously, due largely to the advent of the genomic age, to become the largest group of secreted proteins in gram-negative bacteria. Several of these proteins play essential roles in the pathogenesis of bacterial infections and have been characterized in detail, demonstrating a diverse array of function including the ability to condense host cell actin and to modulate apoptosis. However, most of the autotransporter proteins remain to be characterized. In light of new discoveries and controversies in this research field, this review considers the autotransporter secretion process in the context of the more general field of bacterial protein translocation and exoprotein function.
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Affiliation(s)
- Ian R Henderson
- Division of Immunity and Infection, University of Birmingham, Birmingham B15 2TT, UK.
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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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