1
|
Zakaria FR, Chen CY, Li J, Wang S, Payne GF, Bentley WE. Redox active plant phenolic, acetosyringone, for electrogenetic signaling. Sci Rep 2024; 14:9666. [PMID: 38671069 PMCID: PMC11053109 DOI: 10.1038/s41598-024-60191-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2023] [Accepted: 04/19/2024] [Indexed: 04/28/2024] Open
Abstract
Redox is a unique, programmable modality capable of bridging communication between biology and electronics. Previous studies have shown that the E. coli redox-responsive OxyRS regulon can be re-wired to accept electrochemically generated hydrogen peroxide (H2O2) as an inducer of gene expression. Here we report that the redox-active phenolic plant signaling molecule acetosyringone (AS) can also induce gene expression from the OxyRS regulon. AS must be oxidized, however, as the reduced state present under normal conditions cannot induce gene expression. Thus, AS serves as a "pro-signaling molecule" that can be activated by its oxidation-in our case by application of oxidizing potential to an electrode. We show that the OxyRS regulon is not induced electrochemically if the imposed electrode potential is in the mid-physiological range. Electronically sliding the applied potential to either oxidative or reductive extremes induces this regulon but through different mechanisms: reduction of O2 to form H2O2 or oxidation of AS. Fundamentally, this work reinforces the emerging concept that redox signaling depends more on molecular activities than molecular structure. From an applications perspective, the creation of an electronically programmed "pro-signal" dramatically expands the toolbox for electronic control of biological responses in microbes, including in complex environments, cell-based materials, and biomanufacturing.
Collapse
Affiliation(s)
- Fauziah Rahma Zakaria
- Fischell Department of Bioengineering, University of Maryland, College Park, MD, USA
- Institute for Bioscience and Biotechnology Research, Rockville, MD, USA
- Robert E. Fischell Institute for Biomedical Devices, University of Maryland, College Park, MD, USA
| | - Chen-Yu Chen
- Fischell Department of Bioengineering, University of Maryland, College Park, MD, USA
- Institute for Bioscience and Biotechnology Research, Rockville, MD, USA
- Robert E. Fischell Institute for Biomedical Devices, University of Maryland, College Park, MD, USA
| | - Jinyang Li
- Fischell Department of Bioengineering, University of Maryland, College Park, MD, USA
- Institute for Bioscience and Biotechnology Research, Rockville, MD, USA
- Robert E. Fischell Institute for Biomedical Devices, University of Maryland, College Park, MD, USA
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA
| | - Sally Wang
- Fischell Department of Bioengineering, University of Maryland, College Park, MD, USA
- Institute for Bioscience and Biotechnology Research, Rockville, MD, USA
- Robert E. Fischell Institute for Biomedical Devices, University of Maryland, College Park, MD, USA
| | - Gregory F Payne
- Institute for Bioscience and Biotechnology Research, Rockville, MD, USA.
- Robert E. Fischell Institute for Biomedical Devices, University of Maryland, College Park, MD, USA.
| | - William E Bentley
- Fischell Department of Bioengineering, University of Maryland, College Park, MD, USA.
- Institute for Bioscience and Biotechnology Research, Rockville, MD, USA.
- Robert E. Fischell Institute for Biomedical Devices, University of Maryland, College Park, MD, USA.
| |
Collapse
|
2
|
Li Y, Tang D, Liu Z, Chen J, Cheng B, Kumar R, Yer H, Li Y. An Improved Procedure for Agrobacterium-Mediated Transformation of ‘Carrizo’ Citrange. PLANTS 2022; 11:plants11111457. [PMID: 35684233 PMCID: PMC9183180 DOI: 10.3390/plants11111457] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Revised: 05/23/2022] [Accepted: 05/25/2022] [Indexed: 11/16/2022]
Abstract
Although several protocols for genetic transformation of citrus have been published, it is highly desirable to further improve its efficiency. Here we report treatments of Agrobacterium cells and citrus explants prior to and during co-cultivation process to enhance transformation efficiency using a commercially used rootstock ‘Carrizo’ citrange [Citrus sinensis (L.) Osb. × Poncirius trifoliata (L.) Raf.] as a model plant. We found explants from light-grown seedlings exhibited higher transformation efficiency than those from etiolated seedlings. We pre-cultured Agrobacterium cells in a 1/10 MS, 0.5 g/L 2-(N-morpholino) ethanesulfonic acid (MES) and 100 µM acetosyringone liquid medium for 6 h at 25 °C before used to infect citrus explants. We incubated epicotyl segments in an MS liquid medium containing 13.2 µM 6-BA, 4.5 µM 2,4-D, 0.5 µM NAA for 3 h at 25 °C prior to Agrobacterium infection. In the co-cultivation medium, we added 30 µM paclobutrazol and 10 µM lipoic acid. Each of these treatments significantly increased the efficiencies of transformation up to 30.4% (treating Agrobacterium with acetosyringone), 31.8% (treating explants with cytokinin and auxin), 34.9% (paclobutrazol) and 38.6% (lipoic acid), respectively. When the three treatments were combined, we observed that the transformation efficiency was enhanced from 11.5% to 52.3%. The improvement of genetic transformation efficiency mediated by these three simple treatments may facilitate more efficient applications of transgenic and gene editing technologies for functional characterization of citrus genes and for genetic improvement of citrus cultivars.
Collapse
Affiliation(s)
- Yanjun Li
- Department of Plant Science, University of Connecticut, Storrs, CT 06269, USA; (Y.L.); (D.T.); (R.K.); (H.Y.)
| | - Dan Tang
- Department of Plant Science, University of Connecticut, Storrs, CT 06269, USA; (Y.L.); (D.T.); (R.K.); (H.Y.)
- Horticulture and Landscape College, Hunan Agricultural University, Changsha 410128, China
| | - Zongrang Liu
- Appalachian Fruit Research Station, Agricultural Research Service, U.S. Department of Agriculture, Kearneysville, WV 25430, USA;
| | - Jianjun Chen
- Mid-Florida Research and Education Center, Department of Environmental Horticulture, Institute of Food and Agricultural Sciences, University of Florida, Apopka, FL 32703, USA;
| | - Baoping Cheng
- Plant Protection Research Institute, Guangdong Academy of Agricultural Sciences, Guangdong Provincial Key Laboratory of High Technology for Plant Protection, Guangzhou 510640, China;
| | - Rahul Kumar
- Department of Plant Science, University of Connecticut, Storrs, CT 06269, USA; (Y.L.); (D.T.); (R.K.); (H.Y.)
| | - Huseyin Yer
- Department of Plant Science, University of Connecticut, Storrs, CT 06269, USA; (Y.L.); (D.T.); (R.K.); (H.Y.)
| | - Yi Li
- Department of Plant Science, University of Connecticut, Storrs, CT 06269, USA; (Y.L.); (D.T.); (R.K.); (H.Y.)
- Correspondence: ; Tel.: +1-(860)-486-6780
| |
Collapse
|
3
|
Comparative Transcriptome Analysis of Agrobacterium tumefaciens Reveals the Molecular Basis for the Recalcitrant Genetic Transformation of Camellia sinensis L. Biomolecules 2022; 12:biom12050688. [PMID: 35625616 PMCID: PMC9138961 DOI: 10.3390/biom12050688] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Revised: 05/06/2022] [Accepted: 05/09/2022] [Indexed: 11/17/2022] Open
Abstract
Tea (Camellia sinensis L.), an important economic crop, is recalcitrant to Agrobacterium-mediated transformation (AMT), which has seriously hindered the progress of molecular research on this species. The mechanisms leading to low efficiency of AMT in tea plants, related to the morphology, growth, and gene expression of Agrobacterium tumefaciens during tea-leaf explant infection, were compared to AMT of Nicotiana benthamiana leaves in the present work. Scanning electron microscopy (SEM) images showed that tea leaves induced significant morphological aberrations on bacterial cells and affected pathogen–plant attachment, the initial step of a successful AMT. RNA sequencing and transcriptomic analysis on Agrobacterium at 0, 3 and 4 days after leaf post-inoculation resulted in 762, 1923 and 1656 differentially expressed genes (DEGs) between the tea group and the tobacco group, respectively. The expressions of genes involved in bacterial fundamental metabolic processes, ATP-binding cassette (ABC) transporters, two-component systems (TCSs), secretion systems, and quorum sensing (QS) systems were severely affected in response to the tea-leaf phylloplane. Collectively, these results suggest that compounds in tea leaves, especially gamma-aminobutyrate (GABA) and catechins, interfered with plant–pathogen attachment, essential minerals (iron and potassium) acquisition, and quorum quenching (QQ) induction, which may have been major contributing factors to hinder AMT efficiency of the tea plant.
Collapse
|
4
|
Tiwari M, Gautam N, Indoliya Y, Kidwai M, Mishra AK, Chakrabarty D. A tau class GST, OsGSTU5, interacts with VirE2 and modulates the Agrobacterium-mediated transformation in rice. PLANT CELL REPORTS 2022; 41:873-891. [PMID: 35067774 DOI: 10.1007/s00299-021-02824-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2021] [Accepted: 12/08/2021] [Indexed: 05/27/2023]
Abstract
OsGSTU5 interacts and glutathionylates the VirE2 protein of Agrobacterium and its (OsGSTU5) overexpression and downregulation showed a low and high AMT efficiency in rice, respectively. During Agrobacterium-mediated transformation (AMT), T-DNA along with several virulence proteins such as VirD2, VirE2, VirE3, VirD5, and VirF enter the plant cytoplasm. VirE2 serves as a single-stranded DNA binding (SSB) protein that assists the cytoplasmic trafficking of T-DNA inside the host cell. Though the regulatory roles of VirE2 have been established, the cellular reaction of their host, especially in monocots, has not been characterized in detail. This study identified a cellular interactor of VirE2 from the cDNA library of rice. The identified plant protein encoded by the gene cloned from rice was designated OsGSTU5, it interacted specifically with VirE2 in the host cytoplasm. OsGSTU5 was upregulated during Agrobacterium infection and involved in the post-translational glutathionylation of VirE2 (gVirE2). Interestingly, the in silico analysis showed that the 'gVirE2 + ssDNA' complex was structurally less stable than the 'VirE2 + ssDNA' complex. The gel shift assay also confirmed the attenuated SSB property of gVirE2 over VirE2. Moreover, knock-down and overexpression of OsGSTU5 in rice showed increased and decreased T-DNA expression, respectively after Agrobacterium infection. The present finding establishes the role of OsGSTU5 as an important target for modulation of AMT efficiency in rice.
Collapse
Affiliation(s)
- Madhu Tiwari
- Biotechnology and Molecular Biology Division, CSIR-National Botanical Research Institute, Lucknow, 226001, India
- Laboratory of Microbial Genetics, Department of Botany, Banaras Hindu University, Varanasi, 221005, India
| | - Neelam Gautam
- Biotechnology and Molecular Biology Division, CSIR-National Botanical Research Institute, Lucknow, 226001, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India
| | - Yuvraj Indoliya
- Biotechnology and Molecular Biology Division, CSIR-National Botanical Research Institute, Lucknow, 226001, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India
| | - Maria Kidwai
- Biotechnology and Molecular Biology Division, CSIR-National Botanical Research Institute, Lucknow, 226001, India
| | - Arun Kumar Mishra
- Laboratory of Microbial Genetics, Department of Botany, Banaras Hindu University, Varanasi, 221005, India
| | - Debasis Chakrabarty
- Biotechnology and Molecular Biology Division, CSIR-National Botanical Research Institute, Lucknow, 226001, India.
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India.
| |
Collapse
|
5
|
Jimenez-Gόngora T, Tan H, Lozano-Durán R. Transient Overexpression of E2Fb to Induce Cell Divisions in Nicotiana benthamiana Pavement Cells. Methods Mol Biol 2022; 2382:115-127. [PMID: 34705236 DOI: 10.1007/978-1-0716-1744-1_7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
Abstract
The availability of a fast and controlled mitotic model system that could simplify the generation of genetic material and reduce the experimental time from months to days would largely benefit research in plant cell division. In this protocol, we propose the use of pavement cells of Nicotiana benthamiana leaves to study cell division, which is artificially induced by Agrobacterium-mediated transient overexpression of the transcription factor E2Fb. The cell division-inducing overexpression of E2Fb can be combined with the expression of fluorescent protein-tagged proteins of interest or with dyes, which could be visualized throughout the cell cycle under the microscope. This simple and affordable method enables the study of cell cycle regulation and cell division in plants, from genome replication to cell wall formation, in a fast and controlled manner, and can be used for functional studies when coupled with chemical inhibitors or reverse genetic approaches.
Collapse
Affiliation(s)
- Tamara Jimenez-Gόngora
- Shanghai Center for Plant Stress Biology, CAS Center of Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai, China
- Center for Research in Agricultural Genomics (CRAG), Barcelona, Spain
| | - Huang Tan
- Shanghai Center for Plant Stress Biology, CAS Center of Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Rosa Lozano-Durán
- Shanghai Center for Plant Stress Biology, CAS Center of Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai, China.
| |
Collapse
|
6
|
Li X, Yang Q, Peng L, Tu H, Lee LY, Gelvin SB, Pan SQ. Agrobacterium-delivered VirE2 interacts with host nucleoporin CG1 to facilitate the nuclear import of VirE2-coated T complex. Proc Natl Acad Sci U S A 2020; 117:26389-26397. [PMID: 33020260 PMCID: PMC7584991 DOI: 10.1073/pnas.2009645117] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Agrobacterium tumefaciens is the causal agent of crown gall disease. The bacterium is capable of transferring a segment of single-stranded DNA (ssDNA) into recipient cells during the transformation process, and it has been widely used as a genetic modification tool for plants and nonplant organisms. Transferred DNA (T-DNA) has been proposed to be escorted by two virulence proteins, VirD2 and VirE2, as a nucleoprotein complex (T-complex) that targets the host nucleus. However, it is not clear how such a proposed large DNA-protein complex is delivered through the host nuclear pore in a natural setting. Here, we studied the natural nuclear import of the Agrobacterium-delivered ssDNA-binding protein VirE2 inside plant cells by using a split-GFP approach with a newly constructed T-DNA-free strain. Our results demonstrate that VirE2 is targeted into the host nucleus in a VirD2- and T-DNA-dependent manner. In contrast with VirD2 that binds to plant importin α for nuclear import, VirE2 directly interacts with the host nuclear pore complex component nucleoporin CG1 to facilitate its nuclear uptake and the transformation process. Our data suggest a cooperative nuclear import model in which T-DNA is guided to the host nuclear pore by VirD2 and passes through the pore with the assistance of interactions between VirE2 and host nucleoporin CG1. We hypothesize that this large linear nucleoprotein complex (T-complex) is targeted to the nucleus by a "head" guide from the VirD2-importin interaction and into the nucleus by a lateral assistance from the VirE2-nucleoporin interaction.
Collapse
Affiliation(s)
- Xiaoyang Li
- Department of Biological Sciences, National University of Singapore, Singapore 117543
| | - Qinghua Yang
- Department of Biological Sciences, National University of Singapore, Singapore 117543
| | - Ling Peng
- Department of Biological Sciences, National University of Singapore, Singapore 117543
| | - Haitao Tu
- School of Stomatology and Medicine, Foshan University, Foshan 528000, China
| | - Lan-Ying Lee
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907
| | - Stanton B Gelvin
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907
| | - Shen Q Pan
- Department of Biological Sciences, National University of Singapore, Singapore 117543;
| |
Collapse
|
7
|
Zuniga-Soto E, Fitzpatrick DA, Doohan FM, Mullins E. Insights into the transcriptomic response of the plant engineering bacterium Ensifer adhaerens OV14 during transformation. Sci Rep 2019; 9:10344. [PMID: 31316079 PMCID: PMC6637203 DOI: 10.1038/s41598-019-44648-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Accepted: 05/08/2019] [Indexed: 11/08/2022] Open
Abstract
The ability to engineer plant genomes has been primarily driven by the soil bacterium Agrobacterium tumefaciens but recently the potential of alternative rhizobia such as Rhizobium etli and Ensifer adhaerens OV14, the latter of which supports Ensifer Mediated Transformation (EMT) has been reported. Surprisingly, a knowledge deficit exists in regards to understanding the whole genome processes underway in plant transforming bacteria, irrespective of the species. To begin to address the issue, we undertook a temporal RNAseq-based profiling study of E. adhaerens OV14 in the presence/absence of Arabidopsis thaliana tissues. Following co-cultivation with root tissues, 2333 differentially expressed genes (DEGs) were noted. Meta-analysis of the RNAseq data sets identified a clear shift from plasmid-derived gene expression to chromosomal-based transcription within the early stages of bacterium-plant co-cultivation. During this time, the number of differentially expressed prokaryotic genes increased steadily out to 7 days co-cultivation, a time at which optimum rates of transformation were observed. Gene ontology evaluations indicated a role for both chromosomal and plasmid-based gene families linked specifically with quorum sensing, flagellin production and biofilm formation in the process of EMT. Transcriptional evaluation of vir genes, housed on the pCAMBIA 5105 plasmid in E. adhaerens OV14 confirmed the ability of E. adhaerens OV14 to perceive and activate its transcriptome in response to the presence of 200 µM of acetosyringone. Significantly, this is the first study to characterise the whole transcriptomic response of a plant engineering bacterium in the presence of plant tissues and provides a novel insight into prokaryotic genetic processes that support T-DNA transfer.
Collapse
Affiliation(s)
- Evelyn Zuniga-Soto
- Department of Crop Science, Teagasc Crops Research Centre, Oak Park, Carlow, Ireland
- School of Biology and Environmental Sciences, University College Dublin, Belfield, Dublin 4, Ireland
| | - David A Fitzpatrick
- Department of Biology, National University of Ireland Maynooth, Maynooth, Ireland
| | - Fiona M Doohan
- School of Biology and Environmental Sciences, University College Dublin, Belfield, Dublin 4, Ireland
| | - Ewen Mullins
- Department of Crop Science, Teagasc Crops Research Centre, Oak Park, Carlow, Ireland.
| |
Collapse
|
8
|
Niche Construction and Exploitation by Agrobacterium: How to Survive and Face Competition in Soil and Plant Habitats. Curr Top Microbiol Immunol 2018; 418:55-86. [PMID: 29556826 DOI: 10.1007/82_2018_83] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Agrobacterium populations live in different habitats (bare soil, rhizosphere, host plants), and hence face different environmental constraints. They have evolved the capacity to exploit diverse resources and to escape plant defense and competition from other microbiota. By modifying the genome of their host, Agrobacterium populations exhibit the remarkable ability to construct and exploit the ecological niche of the plant tumors that they incite. This niche is characterized by the accumulation of specific, low molecular weight compounds termed opines that play a critical role in Agrobacterium 's lifestyle. We present and discuss the functions, advantages, and costs associated with this niche construction and exploitation.
Collapse
|
9
|
Tu H, Li X, Yang Q, Peng L, Pan SQ. Real-Time Trafficking of Agrobacterium Virulence Protein VirE2 Inside Host Cells. Curr Top Microbiol Immunol 2018; 418:261-286. [PMID: 30182197 DOI: 10.1007/82_2018_131] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
A. tumefaciens delivers T-DNA and virulence proteins, including VirE2, into host plant cells, where T-DNA is proposed to be protected by VirE2 molecules as a nucleoprotein complex (T-complex) and trafficked into the nucleus. VirE2 is a protein that can self-aggregate and contains targeting sequences so that it can efficiently move from outside of a cell to the nucleus. We adopted a split-GFP approach and generated a VirE2-GFP fusion which retains the self-aggregating property and the targeting sequences. The fusion protein is fully functional and can move inside cells in real time in a readily detectable format: fluorescent and unique filamentous aggregates. Upon delivery mediated by the bacterial type IV secretion system (T4SS), VirE2-GFP is internalized into the plant cells via clathrin adaptor complex AP2-mediated endocytosis. Subsequently, VirE2-GFP binds to membrane structures such as the endoplasmic reticulum (ER) and is trafficked within the cell. This enables us to observe the highly dynamic activities of the cell. If a compound, a gene, or a condition affects the cell, the cellular dynamics shown by the VirE2-GFP will be affected and thus readily observed by confocal microscopy. This represents an excellent model to study the delivery and trafficking of an exogenously produced and delivered protein inside a cell in a natural setting in real time. The model may be used to explore the theoretical and applied aspects of natural protein delivery and targeting.
Collapse
Affiliation(s)
- Haitao Tu
- School of Stomatology and Medicine, Foshan Institute of Molecular Bio-Engineering, Foshan University, 528000, Foshan, China
| | - Xiaoyang Li
- Department of Biological Sciences, National University of Singapore, 117543, Singapore, Singapore
| | - Qinghua Yang
- Department of Biological Sciences, National University of Singapore, 117543, Singapore, Singapore
| | - Ling Peng
- Department of Biological Sciences, National University of Singapore, 117543, Singapore, Singapore
| | - Shen Q Pan
- Department of Biological Sciences, National University of Singapore, 117543, Singapore, Singapore.
| |
Collapse
|
10
|
Hepp C, Maier B. Bacterial Translocation Ratchets: Shared Physical Principles with Different Molecular Implementations: How bacterial secretion systems bias Brownian motion for efficient translocation of macromolecules. Bioessays 2017; 39. [PMID: 28895164 DOI: 10.1002/bies.201700099] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2017] [Revised: 08/02/2017] [Indexed: 12/20/2022]
Abstract
Secretion systems enable bacteria to import and secrete large macromolecules including DNA and proteins. While most components of these systems have been identified, the molecular mechanisms of macromolecular transport remain poorly understood. Recent findings suggest that various bacterial secretion systems make use of the translocation ratchet mechanism for transporting polymers across the cell envelope. Translocation ratchets are powered by chemical potential differences generated by concentration gradients of ions or molecules that are specific to the respective secretion systems. Bacteria employ these potential differences for biasing Brownian motion of the macromolecules within the conduits of the secretion systems. Candidates for this mechanism include DNA import by the type II secretion/type IV pilus system, DNA export by the type IV secretion system, and protein export by the type I secretion system. Here, we propose that these three secretion systems employ different molecular implementations of the translocation ratchet mechanism.
Collapse
Affiliation(s)
- Christof Hepp
- Department of Physics Universität zu Köln, Köln, Nordrhein-Westfalen, Germany
| | - Berenike Maier
- Department of Physics Universität zu Köln, Köln, Nordrhein-Westfalen, Germany
| |
Collapse
|
11
|
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]
|
12
|
Agrobacterium-delivered virulence protein VirE2 is trafficked inside host cells via a myosin XI-K-powered ER/actin network. Proc Natl Acad Sci U S A 2017; 114:2982-2987. [PMID: 28242680 DOI: 10.1073/pnas.1612098114] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Agrobacterium tumefaciens causes crown gall tumors on various plants by delivering transferred DNA (T-DNA) and virulence proteins into host plant cells. Under laboratory conditions, the bacterium is widely used as a vector to genetically modify a wide range of organisms, including plants, yeasts, fungi, and algae. Various studies suggest that T-DNA is protected inside host cells by VirE2, one of the virulence proteins. However, it is not clear how Agrobacterium-delivered factors are trafficked through the cytoplasm. In this study, we monitored the movement of Agrobacterium-delivered VirE2 inside plant cells by using a split-GFP approach in real time. Agrobacterium-delivered VirE2 trafficked via the endoplasmic reticulum (ER) and F-actin network inside plant cells. During this process, VirE2 was aggregated as filamentous structures and was present on the cytosolic side of the ER. VirE2 movement was powered by myosin XI-K. Thus, exogenously produced and delivered VirE2 protein can use the endogenous host ER/actin network for movement inside host cells. The A. tumefaciens pathogen hijacks the conserved host infrastructure for virulence trafficking. Well-conserved infrastructure may be useful for Agrobacterium to target a wide range of recipient cells and achieve a high efficiency of transformation.
Collapse
|
13
|
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.
Collapse
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
| |
Collapse
|
14
|
Berta P, Bourg G, Hanna N, Saadeh B, Armengaud J, Patey G, O'Callaghan D. The Brucella suis IbpA heat-shock chaperone is not required for virulence or for expression of the VirB type IV secretion system VirB8 protein. Lett Appl Microbiol 2014; 58:564-8. [PMID: 24517122 DOI: 10.1111/lam.12231] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2013] [Revised: 02/03/2014] [Accepted: 02/03/2014] [Indexed: 11/28/2022]
Abstract
UNLABELLED Brucella suis, facultative intracellular bacterial pathogen of mammals, and Agrobacterium tumefaciens, a plant pathogen, both use a VirB type IV secretion system (T4SS) to translocate effector molecules into host cells. HspL, an α-crystalline-type small heat-shock protein, acts as a chaperone for the Agrobacterium VirB8 protein, an essential component of the VirB system. An Agrobacterium mutant lacking hspL is attenuated due to a misfunctional T4SS. We have investigated whether IbpA (BRA0051), the Brucella HspL homologue, plays a similar role. Unlike HspL, IbpA does not interact with VirB8, and an IbpA mutant shows full virulence and no defect in VirB expression. These data show that the Brucella α-crystalline-type small heat-shock protein IbpA is not required for Brucella virulence. SIGNIFICANCE AND IMPACT OF STUDY Many bacteria use type IV secretion systems (T4SS), multi-protein machines, to translocate DNA and protein substrates across their envelope. Understanding how T4SS function is important as they play major roles in the spread of plasmids carrying antibiotic resistance and in pathogenicity. In the plant pathogen Agrobacterium tumefaciens, HspL, an α-crystalline-type small heat-shock protein, acts as a chaperone for the essential type IV secretion system component VirB8. Here, we show that this is not the case for all T4SS; in the zoonotic pathogen Brucella suis, IbpA, the protein most related to HspL, does not play this role.
Collapse
Affiliation(s)
- P Berta
- INSERM U1047, UFR Médecine, Nîmes, France; UFR de Médecine, Université Montpellier 1, Nîmes, France; Département Sciences et Arts, Université de Nîmes, Nîmes, France
| | | | | | | | | | | | | |
Collapse
|
15
|
Li X, Yang Q, Tu H, Lim Z, Pan SQ. Direct visualization of Agrobacterium-delivered VirE2 in recipient cells. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2014; 77:487-95. [PMID: 24299048 PMCID: PMC4282531 DOI: 10.1111/tpj.12397] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2013] [Revised: 11/15/2013] [Accepted: 11/27/2013] [Indexed: 05/18/2023]
Abstract
Agrobacterium tumefaciens is a natural genetic engineer widely used to deliver DNA into various recipients, including plant, yeast and fungal cells. The bacterium can transfer single-stranded DNA molecules (T-DNAs) and bacterial virulence proteins, including VirE2. However, neither the DNA nor the protein molecules have ever been directly visualized after the delivery. In this report, we adopted a split-GFP approach: the small GFP fragment (GFP11) was inserted into VirE2 at a permissive site to create the VirE2-GFP11 fusion, which was expressed in A. tumefaciens; and the large fragment (GFP1-10) was expressed in recipient cells. Upon delivery of VirE2-GFP11 into the recipient cells, GFP fluorescence signals were visualized. VirE2-GFP11 was functional like VirE2; the GFP fusion movement could indicate the trafficking of Agrobacterium-delivered VirE2. As the natural host, all plant cells seen under a microscope received the VirE2 protein in a leaf-infiltration assay; most of VirE2 moved at a speed of 1.3-3.1 μm sec⁻¹ in a nearly linear direction, suggesting an active trafficking process. Inside plant cells, VirE2-GFP formed filamentous structures of different lengths, even in the absence of T-DNA. As a non-natural host recipient, 51% of yeast cells received VirE2, which did not move inside yeast. All plant cells seen under a microscope transiently expressed the Agrobacterium-delivered transgene, but only 0.2% yeast cells expressed the transgene. This indicates that Agrobacterium is a more efficient vector for protein delivery than T-DNA transformation for a non-natural host recipient: VirE2 trafficking is a limiting factor for the genetic transformation of a non-natural host recipient. The split-GFP approach could enable the real-time visualization of VirE2 trafficking inside recipient cells.
Collapse
Affiliation(s)
- Xiaoyang Li
- Department of Biological Sciences, National University of SingaporeSingapore, 117543, Singapore
| | - Qinghua Yang
- Department of Biological Sciences, National University of SingaporeSingapore, 117543, Singapore
| | - Haitao Tu
- Department of Biological Sciences, National University of SingaporeSingapore, 117543, Singapore
| | - Zijie Lim
- Department of Biological Sciences, National University of SingaporeSingapore, 117543, Singapore
| | - Shen Q Pan
- Department of Biological Sciences, National University of SingaporeSingapore, 117543, Singapore
| |
Collapse
|
16
|
Chumakov MI. Protein apparatus for horizontal transfer of agrobacterial T-DNA to eukaryotic cells. BIOCHEMISTRY (MOSCOW) 2013; 78:1321-32. [DOI: 10.1134/s000629791312002x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
|
17
|
Rosen R, Ron EZ. Proteomics of a plant pathogen: Agrobacterium tumefaciens. Proteomics 2011; 11:3134-42. [DOI: 10.1002/pmic.201100019] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2011] [Revised: 03/13/2011] [Accepted: 03/14/2011] [Indexed: 12/31/2022]
|
18
|
Citovsky V, DE Vos G, Zambryski P. Single-Stranded DNA Binding Protein Encoded by the virE Locus of Agrobacterium tumefaciens. Science 2010; 240:501-4. [PMID: 17784072 DOI: 10.1126/science.240.4851.501] [Citation(s) in RCA: 117] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The transfer process of T (transfer)-DNA of Agrobacterium tumefaciens is activated after the induction of the expression of the Ti plasmid virulence (vir) loci by plant signal molecules such as acetosyringone. The vir gene products then act to generate a free transferable single-stranded copy of the T-DNA, designated the T-strand. Although some vir proteins are responsible for the synthesis of the T-strand, others may mediate T-strand transfer to plant cells as part of a DNA-protein complex. Here, a novel 69-kilodalton vir-specific single-stranded DNA binding protein is identified in Agrobacterium harboring a nopaline-type Ti plasmid. This protein binds single-stranded but not double-stranded DNA regardless of nucleotide sequence composition. The molecular size of the vir-specific single-stranded DNA binding protein and its relative abundance in acetosyringone-induced Agrobacterium suggested that it might be the product of the virE locus; molecular cloning and expression of the virE region in Escherichia coli confirmed this prediction.
Collapse
|
19
|
Beijersbergen A, Dulk-Ras AD, Schilperoort RA, Hooykaas PJ. Conjugative Transfer by the Virulence System of Agrobacterium tumefaciens. Science 2010; 256:1324-7. [PMID: 17736763 DOI: 10.1126/science.256.5061.1324] [Citation(s) in RCA: 194] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Agrobacterium tumefaciens transfers part of its Ti plasmid, the transferred DNA (T-DNA), to plant cells during tumor induction. Expression of this T-DNA in plant cells results in their transformation into tumor cells. There are similarities between the process of T-DNA transfer to plants and the process of bacterial conjugation. Here, the T-DNA transfer machinery mediated conjugation between bacteria. Thus, products of the Vir region of the Ti plasmid of Agrobacterium tumefaciens, normally involved in transfer of DNA from bacteria to plants, can direct the conjugative transfer of an IncQ plasmid between agrobacteria.
Collapse
|
20
|
Michel MF, Brasileiro AC, Depierreux C, Otten L, Delmotte F, Jouanin L. Identification of different agrobacterium strains isolated from the same forest nursery. Appl Environ Microbiol 2010; 56:3537-45. [PMID: 16348358 PMCID: PMC185018 DOI: 10.1128/aem.56.11.3537-3545.1990] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Several Agrobacterium strains isolated from the same forest nursery from 1982 to 1988 were compared by serological, biochemical, and DNA-DNA hybridization methods. Similarities among strains belonging to biovar 2 were observed by indirect immunofluorescence, whereas biovar 1 strains showed serological heterogeneity. Electrophoretic analysis of bacterial envelope-associated proteins showed that few bands appeared in the strains belonging to biovar 1, whereas many proteins appeared in the case of biovar 2 strains. Chromosomal DNA was analyzed with six random C58 chromosomal fragments. None of the six probes hybridized to the DNA of the two biovar 2 strains. One of the probes gave the same hybridization pattern with all biovar 1 strains, whereas the other probes yielded different patterns. The vir regions were closely related in the different pathogenic strains. The T-DNA and replication regions were less conserved and showed some variations among the strains.
Collapse
Affiliation(s)
- M F Michel
- Station d'Amélioration des Arbres Forestiers, Institut National de la Recherche Agronomique, Ardon, F-45160 Olivet
| | | | | | | | | | | |
Collapse
|
21
|
Gelvin SB. Agrobacterium in the genomics age. PLANT PHYSIOLOGY 2009; 150:1665-76. [PMID: 19439569 PMCID: PMC2719113 DOI: 10.1104/pp.109.139873] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2009] [Accepted: 05/06/2009] [Indexed: 05/18/2023]
Affiliation(s)
- Stanton B Gelvin
- Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907-1392, USA.
| |
Collapse
|
22
|
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.
Collapse
Affiliation(s)
- Walt Ream
- Department of Microbiology, Oregon State University, Corvallis, OR 97331, USA.
| |
Collapse
|
23
|
Chen SC, Liu HW, Lee KT, Yamakawa T. High-efficiency Agrobacterium rhizogenes-mediated transformation of heat inducible sHSP18.2-GUS in Nicotiana tabacum. PLANT CELL REPORTS 2007; 26:29-37. [PMID: 16874528 DOI: 10.1007/s00299-006-0175-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2005] [Revised: 04/18/2006] [Accepted: 05/02/2006] [Indexed: 05/11/2023]
Abstract
The chimerical gene, Arabidopsis thaliana sHSP18.2 promoter fused to E. coli gusA gene, was Agrobacterium rhizogenes-mediated transformed into Nicotiana tabacum as a heat-regulatable model, and the thermo-inducible expression of GUS activity in N. tabacum transgenic hairy roots was profiled. An activation of A. rhizogenes with acetosyringone (AS) before cocultured with tobacco's leaf disc strongly promoted transgenic hairy roots formation. Transgenic hairy roots formation efficiency of A. rhizogenes precultured with 200 microM AS supplementation was 3.1-fold and 7.5-fold, respectively, compared to the formation efficiency obtained with and without AS supplementation in coculture. Transgenic hairy roots transformed with different AS concentration exhibited a similar pattern of thermo-inducibility after 10 min to 3 h heat treatments detected by GUS expression. The peak of expressed GUS specific activity, 399,530 pmol MUG per mg total protein per min, of the transgenic hairy roots was observed at 48 h after 3 h of 42 degrees C heat treatment, and the expressed GUS specific activity was 7-26 times more than that reported in A. thaliana, tobacco BY-2 cells and Nicotiana plumbaginifolia. Interference caused by AS supplementation on the growth of transgenic hairy roots, time-course of GUS expression and its expression level were not observed.
Collapse
Affiliation(s)
- Shih-Cheng Chen
- Graduate Institute of Microbiology and Biochemistry, National Taiwan University, 1, Sec. 4, Roosevelt Road, Taipei, Taiwan
| | | | | | | |
Collapse
|
24
|
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.
Collapse
Affiliation(s)
- Daphna Frenkiel-Krispin
- Department of Materials and Interfaces, Weizmann Institute of Science, Rehovot 76100, Israel
| | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
25
|
Cho H, Winans SC. VirA and VirG activate the Ti plasmid repABC operon, elevating plasmid copy number in response to wound-released chemical signals. Proc Natl Acad Sci U S A 2005; 102:14843-8. [PMID: 16195384 PMCID: PMC1253548 DOI: 10.1073/pnas.0503458102] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The vir genes of Agrobacterium tumefaciens tumor-inducing (Ti) plasmids direct the transfer of oncogenic portion of the Ti (tumor-inducing) plasmid that is transferred to plant cells (T-DNA) into plant cells and are coordinately induced by plant-released phenolic chemical signals. We have used DNA microarrays, representing all genes of the octopine- and nopaline-type Ti plasmids, to identify all Ti-plasmid-encoded genes in the vir regulons of both plasmids. Acetosyringone (AS) induced the expression of all known members of the vir regulons, as well as a small number of additional genes. Unexpectedly, AS also caused a modest induction of virtually every Ti plasmid gene. This suggested that the copy number of the Ti plasmid might increase in response to AS, a hypothesis confirmed by DNA dot blotting. VirA and VirG were the only Vir proteins required for this copy number increase. Promoter resections and primer extension analysis of the repABC promoter region showed that expression of the promoter closest to repA (promoter P4) was induced by AS. We also identified a sequence resembling a consensus VirG-binding motif approximately 70 nucleotides upstream from the P4 transcription start site. Mutating this sequence blocked the AS-induced copy number increase of a RepABC-dependent miniplasmid, indicating that phospho-VirG increases copy number solely by enhancing repABC expression.
Collapse
Affiliation(s)
- Hongbaek Cho
- Department of Microbiology, Cornell University, Ithaca, NY 14853, USA
| | | |
Collapse
|
26
|
Rediers H, Rainey PB, Vanderleyden J, De Mot R. Unraveling the secret lives of bacteria: use of in vivo expression technology and differential fluorescence induction promoter traps as tools for exploring niche-specific gene expression. Microbiol Mol Biol Rev 2005; 69:217-61. [PMID: 15944455 PMCID: PMC1197422 DOI: 10.1128/mmbr.69.2.217-261.2005] [Citation(s) in RCA: 119] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A major challenge for microbiologists is to elucidate the strategies deployed by microorganisms to adapt to and thrive in highly complex and dynamic environments. In vitro studies, including those monitoring genomewide changes, have proven their value, but they can, at best, mimic only a subset of the ensemble of abiotic and biotic stimuli that microorganisms experience in their natural habitats. The widely used gene-to-phenotype approach involves the identification of altered niche-related phenotypes on the basis of gene inactivation. However, many traits contributing to ecological performance that, upon inactivation, result in only subtle or difficult to score phenotypic changes are likely to be overlooked by this otherwise powerful approach. Based on the premise that many, if not most, of the corresponding genes will be induced or upregulated in the environment under study, ecologically significant genes can alternatively be traced using the promoter trap techniques differential fluorescence induction and in vivo expression technology (IVET). The potential and limitations are discussed for the different IVET selection strategies and system-specific variants thereof. Based on a compendium of genes that have emerged from these promoter-trapping studies, several functional groups have been distinguished, and their physiological relevance is illustrated with follow-up studies of selected genes. In addition to confirming results from largely complementary approaches such as signature-tagged mutagenesis, some unexpected parallels as well as distinguishing features of microbial phenotypic acclimation in diverse environmental niches have surfaced. On the other hand, by the identification of a large proportion of genes with unknown function, these promoter-trapping studies underscore how little we know about the secret lives of bacteria and other microorganisms.
Collapse
Affiliation(s)
- Hans Rediers
- Centre of Microbial and Plant Genetics, Heverlee, Belgium
| | | | | | | |
Collapse
|
27
|
Krishnamohan A, Balaji V, Veluthambi K. Efficient vir gene induction in Agrobacterium tumefaciens requires virA, virG, and vir box from the same Ti plasmid. J Bacteriol 2001; 183:4079-89. [PMID: 11395473 PMCID: PMC95292 DOI: 10.1128/jb.183.13.4079-4089.2001] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2000] [Accepted: 04/17/2001] [Indexed: 11/20/2022] Open
Abstract
The vir genes of octopine, nopaline, and L,L-succinamopine Ti plasmids exhibit structural and functional similarities. However, we observed differences in the interactions between octopine and nopaline vir components. The induction of an octopine virE(A6)::lacZ fusion (pSM358cd) was 2.3-fold higher in an octopine strain (A348) than in a nopaline strain (C58). Supplementation of the octopine virG(A6) in a nopaline strain with pSM358 did not completely restore virE(A6) induction. However, addition of the octopine virA(A6) to the above strain increased virE(A6) induction to a level almost comparable to that in octopine strains. In a reciprocal analysis, the induction of a nopaline virE(C58)::cat fusion (pUCD1553) was two- to threefold higher in nopaline (C58 and T37) strains than in octopine (A348 and Ach5) and L,L-succinamopine (A281) strains. Supplementation of nopaline virA(C58) and virG(C58) in an octopine strain (A348) harboring pUCD1553 increased induction levels of virE(C58)::cat fusion to a level comparable to that in a nopaline strain (C58). Our results suggest that octopine and L,L-succinamopine VirG proteins induce the octopine virE(A6) more efficiently than they do the nopaline virE(C58). Conversely, the nopaline VirG protein induces the nopaline virE(C58) more efficiently than it does the octopine virE(A6). The ability of Bo542 virG to bring about supervirulence in tobacco is observed for an octopine vir helper (LBA4404) but not for a nopaline vir helper (PMP90). Our analyses reveal that quantitative differences exist in the interactions between VirG and vir boxes of different Ti plasmids. Efficient vir gene induction in octopine and nopaline strains requires virA, virG, and vir boxes from the respective Ti plasmids.
Collapse
Affiliation(s)
- A Krishnamohan
- Department of Plant Biotechnology, School of Biotechnology, Madurai Kamaraj University, Madurai 625 021, Tamil Nadu, India
| | | | | |
Collapse
|
28
|
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.
Collapse
Affiliation(s)
- Stanton B. Gelvin
- Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907-1392; e-mail:
| |
Collapse
|
29
|
|
30
|
Lee LY, Gelvin SB, Kado CI. pSa causes oncogenic suppression of Agrobacterium by inhibiting VirE2 protein export. J Bacteriol 1999; 181:186-96. [PMID: 9864329 PMCID: PMC103548 DOI: 10.1128/jb.181.1.186-196.1999] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/1998] [Accepted: 10/09/1998] [Indexed: 11/20/2022] Open
Abstract
When coresident with the Ti (tumor-inducing) plasmid, the 21-kDa product of the osa gene of the plasmid pSa can suppress crown gall tumorigenesis incited by Agrobacterium tumefaciens. Neither T-DNA processing nor vir (virulence) gene induction is affected by the presence of osa in the bacterium. We used Arabidopsis thaliana root segments and tobacco leaf discs to demonstrate that Osa inhibits A. tumefaciens from transforming these plants to the stable phenotypes of tumorigenesis, kanamycin resistance, and stable beta-glucuronidase (GUS) expression. When A. tumefaciens contained osa, the lack of expression of transient GUS activity in infected plant tissues, as well as the lack of systemic viral symptoms following agroinfection of Nicotiana benthamiana by tomato mottle virus, suggested that oncogenic suppression by Osa occurs before T-DNA enters the plant nucleus. The extracellular complementation of an A. tumefaciens virE2 mutant (the T-DNA donor strain) by an A. tumefaciens strain lacking T-DNA but containing a wild-type virE2 gene (the VirE2 donor strain) was blocked when osa was present in the VirE2 donor strain, but not when osa was present in the T-DNA donor strain. These data indicate that osa inhibits VirE2 protein, but not T-DNA export from A. tumefaciens. These data further suggest that VirE2 protein and T-DNA are separately exported from the bacterium. The successful infection of Datura stramonium plants and leaf discs of transgenic tobacco plants expressing VirE2 protein by an A. tumefaciens virE2 mutant carrying osa confirmed that oncogenic suppression by osa does not occur by blocking T-DNA transfer. Overexpression of virB9, virB10, and virB11 in A. tumefaciens did not overcome oncogenic suppression by osa. The finding that the expression of the osa gene by itself, rather than the formation of a conjugal intermediate with pSa, blocks transformation suggests that the mechanism of oncogenic suppression by osa may differ from that of the IncQ plasmid RSF1010.
Collapse
Affiliation(s)
- L Y Lee
- Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907-1392, USA
| | | | | |
Collapse
|
31
|
Chumakov MI, Kurbanova IV. Localization of the protein VirB1 involved in contact formation during conjugation among Agrobacterium cells. FEMS Microbiol Lett 1998; 168:297-301. [PMID: 9835041 DOI: 10.1111/j.1574-6968.1998.tb13287.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Supramembrane structures of Agrobacterium, which link cells during mating, were for the first time visualized using transmission electron microscopy. The initial cell contact was found to be mediated by long pili. Using colloidal gold-labeled, VirB1-specific antibodies, it was established that VirB1 proteins enter into the composition of short pilus-like structures, which emerge at the poles of acetosyringone (AS)-induced agrobacterial cells. Labeling of non-centrifuged agrobacterial cells on a nitrocellulose membrane using colloidal gold-conjugated antibodies to VirB1 showed that the labeled complex could bind to AS-induced cells, but failed to form red stains during incubation with cells of the Ti plasmidless A. tumefaciens strains LBA288 and UBAPF-2.
Collapse
Affiliation(s)
- M I Chumakov
- Institute of Biochemistry and Physiology of Plants and Microorganisms, Russian Academy of Sciences, Saratov, Russia.
| | | |
Collapse
|
32
|
Gelvin SB. Agrobacterium VirE2 proteins can form a complex with T strands in the plant cytoplasm. J Bacteriol 1998; 180:4300-2. [PMID: 9696783 PMCID: PMC107431 DOI: 10.1128/jb.180.16.4300-4302.1998] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/1998] [Accepted: 06/04/1998] [Indexed: 11/20/2022] Open
Abstract
Wild-type VirE2 and VirD2 proteins from Agrobacterium tumefaciens contain nuclear targeting sequences (NLS) that are likely involved in directing transferred T strands to the plant nucleus. An A. tumefaciens virE2 virD2DeltaNLS double mutant was able to form tumors on VirE2-producing transgenic tobacco but not on wild-type tobacco. Because this mutant bacterial strain contains no known T-strand nuclear targeting signal, the data indicate that wild-type VirE2 proteins produced by the plant can interact with the T strands in the plant cytoplasm and direct them to the nucleus.
Collapse
Affiliation(s)
- S B Gelvin
- Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907-1392, USA.
| |
Collapse
|
33
|
Kang HC, Ardourel MY, Guérin B, Monsigny M, Delmotte FM. Purification of two lectins from a nopalin Agrobacterium tumefaciens strain. Biochimie 1998; 80:87-94. [PMID: 9587666 DOI: 10.1016/s0300-9084(98)80060-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Lectins were evidenced on the surface of one Agrobacterium tumefaciens wild strain (82,139) by agglutination test and neoglycoprotein labelling. Bacteria were incubated in the presence of various fluorescein-labelled neoglycoproteins and the binding was assessed by a fluorimetric method. Among the fluorescein-labelled neoglycoproteins tested, the one bearing alpha-D-galactosyl residues was the most efficient. The labelling was optimal at pH 5.0 and naught at pH above 7. The binding was specifically inhibited by homologous fluorescein-free neoglycoproteins. A galactoside-specific lectin was purified to homogeneity by affinity chromatography on agarose-A4 substituted with alpha-D-galactopyranosyl residues. Upon polyacrylamide gel electrophoresis, a single band (M(r) 58,000) was detected. This alpha-D-galactoside-specific lectin agglutinated preferentially human B red blood cells at pH 5.0. Another lectin specific for alpha-L-rhamnoside (M(r) 40,000) not retained on the immobilised galactose was purified by affinity chromatography on alpha-L-rhamnosyl substituted agarose-A4. This L-rhamnoside-specific lectin preferentially agglutinated horse erythrocytes. On the basis of their M(r) and on their sugar specificity, these two lectins are novel lectins with regard to the known sugar-binding proteins present in the Rhizobiaceae family: Agrobacterium, Rhizobium or Bradyrhizobium strains.
Collapse
Affiliation(s)
- H C Kang
- Glycobiologie, Centre de Biophysique Moléculaire, UPR 4301 du CNRS, Orléans, France
| | | | | | | | | |
Collapse
|
34
|
Beaupré CE, Bohne J, Dale EM, Binns AN. Interactions between VirB9 and VirB10 membrane proteins involved in movement of DNA from Agrobacterium tumefaciens into plant cells. J Bacteriol 1997; 179:78-89. [PMID: 8981983 PMCID: PMC178664 DOI: 10.1128/jb.179.1.78-89.1997] [Citation(s) in RCA: 84] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
The 11 VirB proteins from Agrobacterium tumefaciens are predicted to form a membrane-bound complex that mediates the movement of DNA from the bacterium into plant cells. The studies reported here on the possible VirB protein interactions in such a complex demonstrate that VirB9 and VirB10 can each form high-molecular-weight complexes after treatment with a chemical cross-linker. Analysis of nonpolar virB mutants showed that the formation of the VirB10 complexes does not occur in a virB9 mutant and that VirB9 and VirB10 are not components of the same cross-linked complex. VirB9, when stabilized by the concurrent expression of VirB7, was shown to be sufficient to permit VirB10 to cross-link into its usual high-molecular-weight forms in the absence of other Vir proteins. Randomly introduced single point mutations in virB9 resulted in Agrobacterium strains with severely attenuated virulence. Although some of the mutants contained wild-type levels of VirB9 and displayed an unaltered VirB9 cross-linking pattern, VirB10 cross-linking was drastically reduced. We conclude that specific amino acid residues in VirB9 are necessary for interaction with VirB10 resulting in the capacity of VirB10 to participate in high-molecular-weight complexes that can be visualized by chemical cross-linking.
Collapse
Affiliation(s)
- C E Beaupré
- Plant Sciences Institute, Department of Biology, University of Pennsylvania, Philadelphia 19104-6018, USA
| | | | | | | |
Collapse
|
35
|
Natural genetic engineering of plant cells: the molecular biology of crown gall and hairy root disease. World J Microbiol Biotechnol 1996; 12:327-51. [DOI: 10.1007/bf00340209] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Revised: 02/07/1996] [Accepted: 02/10/1996] [Indexed: 11/26/2022]
|
36
|
Wisniewski JP, Delmotte FM. Modulation of carbohydrate-binding capacities and attachment ability of Bradyrhizobium sp. (lupinus) to white lupin roots. Can J Microbiol 1996; 42:234-42. [PMID: 8868230 DOI: 10.1139/m96-035] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The attachment of Bradyrhizobium sp. (Lupinus) strain MSDJ718 to excised roots of white lupin was examined. Maximal attachment occurred at early to middle log phases of bacterial growth. This binding was pH dependent, with an optimal value reached at 6.6. Irrespective of the culture age, the attachment was strongly affected by the calcium concentration of the growth medium: a Ca2+ limitation in the Bergersen medium led to optimal attachment of the bacteria. When L-fucose was added during the attachment assay, a significant inhibition was observed. The binding was stimulated when bacteria were cultivated with lupin root extracts, genistein and genistin (two lupin isoflavonoids), and some monosaccharides. In addition, with a spectrofluorimetric method using fluoresceinylated neoglycoproteins, it was shown that the increase of the attachment of bacteria to host cells was correlated to the increase of the L-fucoside binding capacity of the rhizobial cells. Taken together, the results obtained in the present study evidenced a possible role of the L-fucose specific bacterial lectin previously described in the Rhizobium-lupin host cell recognition.
Collapse
Affiliation(s)
- J P Wisniewski
- Centre national de la recherche scientifique, Orléans, France
| | | |
Collapse
|
37
|
Sundberg C, Meek L, Carroll K, Das A, Ream W. VirE1 protein mediates export of the single-stranded DNA-binding protein VirE2 from Agrobacterium tumefaciens into plant cells. J Bacteriol 1996; 178:1207-12. [PMID: 8576060 PMCID: PMC177787 DOI: 10.1128/jb.178.4.1207-1212.1996] [Citation(s) in RCA: 92] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Agrobacterium tumefaciens transfers single-stranded DNAs (T strands) into plant cells. VirE1 and VirE2, which is a single-stranded DNA binding protein, are important for tumorigenesis. We show that T strands and VirE2 can enter plant cells independently and that export of VirE2, but not of T strands, depends on VirE1.
Collapse
Affiliation(s)
- C Sundberg
- Program in Molecular Biology, Oregon State University, Corvallis 97331, USA
| | | | | | | | | |
Collapse
|
38
|
Vijayachandra K, Palanichelvam K, Veluthambi K. Rice scutellum induces Agrobacterium tumefaciens vir genes and T-strand generation. PLANT MOLECULAR BIOLOGY 1995; 29:125-33. [PMID: 7579158 DOI: 10.1007/bf00019124] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
For successful transformation of a plant by Agrobacterium tumefaciens it is essential that the explant used in cocultivation has the ability to induce Agrobacterium tumour-inducing (Ti) plasmid virulence (vir) genes. Here we report a significant variation in different tissues of Indica rice (Oryza sativa L. cv. Co43) in their ability to induce Agrobacterium tumefaciens vir genes and T-strand generation, using explants preincubated in liquid Murashige and Skoog (MS) medium. An analysis of rice leaf segments revealed that they neither induced vir genes nor inhibited vir gene induction. Of different parts of rice plants of different ages analysed only scutellum from four-day old rice seedlings induced vir genes and generation of T-strands. We observed that the physical presence of preincubated scutella is required for vir gene induction. Conditioned medium from which preincubated scutella were removed did not induce the vir genes. Scutellum-derived calli, cultured for 25 days on medium containing 2,4-D, also induced virE to an appreciable level. These results suggest that scutellum and scutellum-derived calli may be the most susceptible tissues of rice for Agrobacterium-mediated transformation.
Collapse
Affiliation(s)
- K Vijayachandra
- Department of Plant Molecular Biology, School of Biotechnology, Madurai Kamaraj University, India
| | | | | |
Collapse
|
39
|
Transport of pertussis toxin across bacterial and eukaryotic membranes. ACTA ACUST UNITED AC 1995. [DOI: 10.1016/s1874-592x(06)80016-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
|
40
|
Berger BR, Christie PJ. Genetic complementation analysis of the Agrobacterium tumefaciens virB operon: virB2 through virB11 are essential virulence genes. J Bacteriol 1994; 176:3646-60. [PMID: 8206843 PMCID: PMC205554 DOI: 10.1128/jb.176.12.3646-3660.1994] [Citation(s) in RCA: 198] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
The Agrobacterium tumefaciens virB gene products are proposed to assemble into a transport system capable of exporting complexes of DNA and protein across the bacterial envelope en route to plant cells. Nonpolar null mutations were constructed in each of the 11 virB genes of the A. tumefaciens pTiA6NC plasmid. In tumorigenicity assays, delta virB1 mutants exhibited severely attenuated virulence and delta virB2 through delta virB11 mutants exhibited avirulence. NdeI restriction sites introduced at the predicted translational start sites of the virB genes were used to subclone each of the virB genes downstream of the lacZ or virB promoter on broad-host-range plasmids. virB gene expression plasmids were used to define promoter and general sequence requirements for genetic complementation of the deletion mutations. Whereas virB1 and virB2 complemented delta virB1 and delta virB2, respectively, only when expressed in trans from the virB promoter, virB3 through virB11 complemented the corresponding deletion mutations when expressed in trans from either the lacZ or virB promoter. Several virB genes required additional upstream or downstream sequences for complementation: (i) virB2 complemented the delta virB2 mutation only when the complementing plasmid coexpressed virB1 and virB2, (ii) virB6 and virB9 complemented the delta virB6 and delta virB9 mutations only when the complementing plasmids carried at most 55 and 230 bp of sequences residing 5' of these genes, respectively, and (iii) virB7 and virB8 complemented the delta virB7 and delta virB8 mutations only when the complementing plasmid coexpressed virB7 and virB8. These studies established that virB1 is an accessory virulence determinant and virB2 through virB11 are absolutely essential for the A. tumefaciens infection process.
Collapse
Affiliation(s)
- B R Berger
- Department of Microbiology and Molecular Genetics, University of Texas Health Science Center at Houston 77030
| | | |
Collapse
|
41
|
Thorstenson YR, Zambryski PC. The essential virulence protein VirB8 localizes to the inner membrane of Agrobacterium tumefaciens. J Bacteriol 1994; 176:1711-7. [PMID: 8132466 PMCID: PMC205259 DOI: 10.1128/jb.176.6.1711-1717.1994] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Agrobacterium tumefaciens genetically transforms plant cells by transferring a specific DNA fragment from the bacterium through several biological membranes to the plant nucleus where the DNA is integrated. This complex DNA transport process likely involves membrane-localized proteins in both the plant and the bacterium. The 11 hydrophobic or membrane-localized proteins of the virB operon are excellent candidates to have a role in DNA export from agrobacteria. Here, we show by TnphoA mutagenesis and immunogold electron microscopy that one of the VirB proteins, VirB8, is located at the inner membrane. The observation that a virB8::TnphoA fusion restores export of alkaline phosphatase to the periplasm suggests that VirB8 spans the inner membrane. Immunogold labeling of VirB8 was detected on the inner membrane of vir-induced A. tumefaciens by transmission electron microscopy. Compared with that of the controls, VirB8 labeling was significantly greater on the inner membrane than on the other cell compartments. These results confirm the inner membrane localization of VirB8 and strengthen the hypothesis that VirB proteins help form a transfer DNA export channel or gate.
Collapse
Affiliation(s)
- Y R Thorstenson
- Plant Biology Department, University of California, Berkeley 94720
| | | |
Collapse
|
42
|
Shirasu K, Koukolíková-Nicola Z, Hohn B, Kado CI. An inner-membrane-associated virulence protein essential for T-DNA transfer from Agrobacterium tumefaciens to plants exhibits ATPase activity and similarities to conjugative transfer genes. Mol Microbiol 1994; 11:581-8. [PMID: 8152380 DOI: 10.1111/j.1365-2958.1994.tb00338.x] [Citation(s) in RCA: 73] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The 9.5 kb virB operon is the largest of the six major operons in the Ti plasmid vir region. This operon contains eleven genes, the largest of which is virB4. This gene encodes an 84 kDa protein whose function has not been identified. Its roles in conferring virulence on Agrobacterium tumefaciens and in the T-DNA transfer process were determined by generating non-polar mutants by using the Tn5pvirB transposon in which the virB promoter is transcribed downstream of its position of insertion. Several independent mutants were isolated and each insertion site in virB4 was confirmed by nucleotide sequence analysis. These mutants were tested for T-DNA transfer ability by agroinfection and for tumorigenicity by inoculation in Brassica and Datura. All mutants were agroinfection- and tumorigenicity-negative. These data strongly suggest that virB4 is essential for both the interkingdom transfer of the T-DNA and virulence. Furthermore, by using anti-VirB4 serum, the protein product of virB4 was localized to the inner-membrane fraction of A. tumefaciens. Purified VirB4 protein hydrolyses ATP and this activity was quenched by the anti-VirB4 serum. The energy generated by VirB4 ATPase therefore may be used to transfer T-DNA or to assemble the T-DNA transfer apparatus on the bacterial membrane. Protein sequence analyses revealed striking similarities between VirB4 protein and the proteins required for conjugative transfer, which include TraC, TrwK, and TrbE of plasmids F, R388, and RP4, respectively. These findings suggest that VirB proteins play a direct role in the assembly of a conjugative transfer apparatus required for the transfer of the T-DNA from A. tumefaciens to plant cells.
Collapse
Affiliation(s)
- K Shirasu
- Department of Plant Pathology, University of California, Davis 95616
| | | | | | | |
Collapse
|
43
|
Lessl M, Balzer D, Weyrauch K, Lanka E. The mating pair formation system of plasmid RP4 defined by RSF1010 mobilization and donor-specific phage propagation. J Bacteriol 1993; 175:6415-25. [PMID: 8407818 PMCID: PMC206749 DOI: 10.1128/jb.175.20.6415-6425.1993] [Citation(s) in RCA: 89] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Transfer functions of the conjugative plasmid RP4 (IncP alpha) are distributed among distinct regions of the genome, designated Tra1 and Tra2. By deletion analyses, we determined the limits of the Tra1 region, essential for intraspecific Escherichia coli matings. The Tra1 core region encompasses approximately 5.8 kb, including the genes traF, -G, -H, -I, -J, and -K as well as the origin of transfer. The traM gene product, however, is not absolutely required for conjugation but significantly increases transfer efficiency. To determine the transfer phenotype of genes encoded by the Tra2 core region, we generated a series of defined Tra2 mutants. This revealed that at least trbB, -C, -E, -G, and -L are essential for RP4 conjugation. To classify these transfer functions as components of the DNA transfer and replication (Dtr) or of the mating pair formation (Mpf) system, we analyzed the corresponding derivatives with respect to mobilization of IncQ plasmids and donor-specific phage propagation. We found that all of the Tra2 genes listed above and the traG and traF genes of Tra1 are required for RSF1010 mobilization. Expression of traF from Tra1 in conjunction with the Tra2 core was sufficient for phage propagation. This implies that the TraG protein is not directly involved in pilus formation and potentially connects the relaxosome with proteins enabling the membrane passage of the DNA. The proposed roles of the RP4 transfer gene products are discussed in the context of virulence functions encoded by the evolutionarily related Ti T-DNA transfer system of agrobacteria.
Collapse
Affiliation(s)
- M Lessl
- Max-Planck-Institut für Molekulare Genetik, Abteilung Schuster, Berlin, Germany
| | | | | | | |
Collapse
|
44
|
Shirasu K, Kado CI. Membrane location of the Ti plasmid VirB proteins involved in the biosynthesis of a pilin-like conjugative structure on Agrobacterium tumefaciens. FEMS Microbiol Lett 1993; 111:287-94. [PMID: 8405938 DOI: 10.1111/j.1574-6968.1993.tb06400.x] [Citation(s) in RCA: 92] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
The virB operon of the Agrobacterium tumefaciens Ti plasmid encodes 11 proteins. Specific antisera to VirB2, VirB3 and VirB9 were used to locate these virulence proteins in the A. tumefaciens cell. Immunoblot analysis located VirB2 protein to the inner and outer membranes; VirB3 and VirB9 were likewise associated with both membranes, but mainly in the outer membrane. VirB2 is processed from a 12.3-kDa protein into a 7.2-kDa polypeptide. Such sized protein results from cleavage at residue Ala47, upstream of which two additional alanine residues Ala45-Ala46 are contained and bearing resemblance to a signal peptide peptidase-I cleavage sequence. VirB2 and VirB3 sequences are strikingly similar to the pilin biosynthetic proteins TraA and TraL encoded by the tra operon of F and R1-19 plasmids. Since traA encodes a propilin that is cleaved into a 7.2-kDa conjugative pilin product and since this cleavage site is present in both TraA and VirB2, we propose that virB2 encodes a pilin-like protein which together with VirB3 and VirB9 as well as other VirB proteins may be used for interkingdom T-DNA transfer between bacteria and plants.
Collapse
Affiliation(s)
- K Shirasu
- Department of Plant Pathology, University of California, Davis 95616
| | | |
Collapse
|
45
|
Thorstenson YR, Kuldau GA, Zambryski PC. Subcellular localization of seven VirB proteins of Agrobacterium tumefaciens: implications for the formation of a T-DNA transport structure. J Bacteriol 1993; 175:5233-41. [PMID: 8349563 PMCID: PMC204991 DOI: 10.1128/jb.175.16.5233-5241.1993] [Citation(s) in RCA: 85] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Plant cell transformation by Agrobacterium tumefaciens involves the transfer of a single-stranded DNA-protein complex (T-complex) from the bacterium to the plant cell. One of the least understood and important aspects of this process is how the T-complex exits the bacterium. The eleven virB gene products have been proposed to specify the DNA export channel on the basis of their predicted hydrophobicity. To determine the cellular localization of the VirB proteins, two different cell fractionation methods were employed to separate inner and outer membranes. Seven VirB-specific antibodies were used on Western blots (immunoblots) to detect the proteins in the inner and outer membranes and soluble (containing cytoplasm and periplasm) fractions. VirB5 was in both the inner membrane and cytoplasm. Six of the VirB proteins were detected in the membrane fractions only. Three of these, VirB8, VirB9, and VirB10, were present in both inner and outer membrane fractions regardless of the fractionation method used. Three additional VirB proteins, VirB1, VirB4, and VirB11, were found mainly in the inner membrane fraction by one method and were found in both inner and outer membrane fractions by a second method. These results confirm the membrane localization of seven VirB proteins and strengthen the hypothesis that VirB proteins are involved in the formation of a T-DNA export channel or gate. That most of the VirB proteins analyzed are found in both inner and outer membrane fractions suggest that they form a complex pore structure that spans both membranes, and their relative amounts in the two membrane fractions reflect their differential sensitivity to the experimental conditions.
Collapse
Affiliation(s)
- Y R Thorstenson
- Plant Biology Department, University of California, Berkeley 94720
| | | | | |
Collapse
|
46
|
Weiss AA, Johnson FD, Burns DL. Molecular characterization of an operon required for pertussis toxin secretion. Proc Natl Acad Sci U S A 1993; 90:2970-4. [PMID: 8464913 PMCID: PMC46218 DOI: 10.1073/pnas.90.7.2970] [Citation(s) in RCA: 221] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Mutants of Bordetella pertussis which are defective in secretion of pertussis toxin were isolated and characterized. The region of the B. pertussis chromosome identified by mutagenesis as playing a role in transport of pertussis toxin was sequenced. Analysis of this region revealed eight open reading frames, seven of which predict a protein exhibiting homology with one of the VirB proteins of Agrobacterium tumefaciens, which are involved in the transport of the T-DNA molecule across bacterial and plant membranes. Thus a set of accessory proteins are most likely involved in the secretion of pertussis toxin, and these proteins appear to be members of a family of proteins involved in the secretion of macromolecules from bacteria.
Collapse
Affiliation(s)
- A A Weiss
- Department of Microbiology and Immunology, Virginia Commonwealth University, Richmond 23298
| | | | | |
Collapse
|
47
|
Berger BR, Christie PJ. The Agrobacterium tumefaciens virB4 gene product is an essential virulence protein requiring an intact nucleoside triphosphate-binding domain. J Bacteriol 1993; 175:1723-34. [PMID: 8449880 PMCID: PMC203967 DOI: 10.1128/jb.175.6.1723-1734.1993] [Citation(s) in RCA: 104] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Products of the approximately 9.5-kb virB operon are proposed to direct the export of T-DNA/protein complexes across the Agrobacterium tumefaciens envelope en route to plant cells. The presence of conserved nucleoside triphosphate (NTP)-binding domains in VirB4 and VirB11 suggests that one or both proteins couple energy, via NTP hydrolysis, to T-complex transport. To assess the importance of VirB4 for virulence, a nonpolar virB4 null mutation was introduced into the pTiA6NC plasmid of strain A348. The 2.37-kb virB4 coding sequence was deleted precisely by oligonucleotide-directed mutagenesis in vitro. The resulting delta virB4 mutation was exchanged for the wild-type allele by two sequential recombination events with the counterselectable Bacillus subtilis sacB gene. Two derivatives, A348 delta B4.4 and A348 delta B4.5, sustained a nonpolar deletion of the wild-type virB4 allele, as judged by Southern blot hybridization and immunoblot analyses with antibodies specific for VirB4, VirB5, VirB10, and VirB11. Transcription of wild-type virB4 from the lac promoter restored virulence to the nonpolar null mutants on a variety of dicotyledonous species, establishing virB4 as an essential virulence gene. A substitution of glutamine for Lys-439 and a deletion of Gly-438, Lys-439, and Thr-440 within the glycine-rich NTP-binding domain (Gly-Pro-Iso-Gly-Arg-Gly-Lys-Thr) abolished complementation of A348 delta B4.4 or A348 delta B4.5, demonstrating that an intact NTP-binding domain is critical for VirB4 function. Merodiploids expressing both the mutant and wild-type virB4 alleles exhibited lower virulence than A348, suggesting that VirB4, a cytoplasmic membrane protein, may contribute as a homo- or heteromultimer to A. tumefaciens virulence.
Collapse
Affiliation(s)
- B R Berger
- Department of Microbiology and Molecular Genetics, University of Texas Health Science Center, Houston 77030
| | | |
Collapse
|
48
|
Sequence similarities between the RP4 Tra2 and the Ti VirB region strongly support the conjugation model for T-DNA transfer. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(19)88726-4] [Citation(s) in RCA: 122] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
|
49
|
Abstract
The discovery in 1977 that Agrobacterium species can transfer a discrete segment of oncogenic DNA (T-DNA) to the genome of host plant cells has stimulated an intense interest in the molecular biology underlying these plant-microbe associations. This attention in turn has resulted in a series of insights about the biology of these organisms that continue to accumulate at an ever-increasing rate. This excitement was due in part to the notion that this unprecedented interkingdom DNA transfer could be exploited to create transgenic plants containing foreign genes of scientific or commercial importance. In the course of these discoveries, Agrobacterium became one of the best available models for studying the molecular interactions between bacteria and higher organisms. One extensively studied aspect of this association concerns the exchange of chemical signals between Agrobacterium spp. and host plants. Agrobacterium spp. can recognize no fewer than five classes of low-molecular-weight compounds released from plants, and other classes probably await discovery. The most widely studied of these are phenolic compounds, which stimulate the transcription of the genes needed for infection. Other compounds include specific monosaccharides and acidic environments which potentiate vir gene induction, acidic polysaccharides which induce one or more chromosomal genes, and a family of compounds called opines which are released from tumorous plant cells to the bacteria as nutrient sources. Agrobacterium spp. in return release a variety of chemical compounds to plants. The best understood is the transferred DNA itself, which contains genes that in various ways upset the balance of phytohormones, ultimately causing neoplastic cell proliferation. In addition to transferring DNA, some Agrobacterium strains directly secrete phytohormones. Finally, at least some strains release a pectinase, which degrades a component of plant cell walls.
Collapse
Affiliation(s)
- S C Winans
- Section of Microbiology, Cornell University, Ithaca, New York 14853
| |
Collapse
|
50
|
Gray J, Wang J, Gelvin SB. Mutation of the miaA gene of Agrobacterium tumefaciens results in reduced vir gene expression. J Bacteriol 1992; 174:1086-98. [PMID: 1735704 PMCID: PMC206401 DOI: 10.1128/jb.174.4.1086-1098.1992] [Citation(s) in RCA: 56] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
vir regulon expression in Agrobacterium tumefaciens involves both chromosome- and Ti-plasmid-encoded gene products. We have isolated and characterized a new chromosomal gene that when mutated results in a 2- to 10-fold reduction in the induced expression of vir genes by acetosyringone. This reduced expression occurs in AB minimal medium (pH 5.5) containing either sucrose or glucose and containing phosphate at high or low concentrations. The locus was cloned and used to complement A. tumefaciens strains harboring Tn5 insertions in the gene. Sequence analysis of this locus revealed an open reading frame with strong homology to the miaA locus of Escherichia coli and the mod5 locus of Saccharomyces cerevisiae. These genes encode tRNA: isopentenyltransferase enzymes responsible for the specific modification of the A-37 residue in UNN codon tRNA species. The function of the homologous gene in A. tumefaciens was proven by genetic complementation of E. coli miaA mutant strains. tRNA undermodification in A. tumefaciens miaA mutant strains may reduce vir gene expression by causing a reduced translation efficiency. A slight reduction in the virulence of these mutant Agrobacterium strains on red potato plants, but not on tobacco, tomato, kalanchoe, or sunflower plants, was observed.
Collapse
Affiliation(s)
- J Gray
- Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907-1392
| | | | | |
Collapse
|