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Pierrat X, Pham A, Wong JPH, Al-Mayyah Z, Persat A. Engineering Agrobacterium tumefaciens Adhesion to Target Cells. ACS Synth Biol 2022; 11:2662-2671. [PMID: 35881049 DOI: 10.1021/acssynbio.2c00069] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Agrobacterium tumefaciens is a plant pathogen commonly repurposed for genetic modification of crops. Despite its versatility, it remains inefficient at transferring DNA to many hosts, including to animal cells. Like many pathogens, physical contact between A. tumefaciens and host cells promotes infection efficacy. Thus, improving the strength and specificity of A. tumefaciens to target cells has the potential for enhancing DNA transfer for biotechnological and therapeutic purposes. Here, we demonstrate a methodology for engineering genetically encoded exogeneous adhesins at the surface of A. tumefaciens. We identified an autotransporter gene we named Aat that is predicted to show canonical β-barrel and passenger domains. We engineered the β-barrel scaffold and linker (Aatβ) to display synthetic adhesins susceptible to rewire A. tumefaciens to alternative host targets. As a proof of concept, we leveraged the versatility of a VHH domain to rewire A. tumefaciens adhesion to yeast and mammalian hosts displaying a GFP target receptor. Finally, to demonstrate how synthetic A. tumefaciens adhesion can improve transfer to host cells, we showed improved protein translocation into HeLa cells using a sensitive split luciferase reporter system. Engineering A. tumefaciens adhesion has therefore a strong potential in generating complex heterogeneous cellular assemblies and in improving DNA transfer efficiency against non-natural hosts.
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Affiliation(s)
- Xavier Pierrat
- School of Life Sciences, Institute of Bioengineering and Global Health Institute, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
| | - Alix Pham
- School of Life Sciences, Institute of Bioengineering and Global Health Institute, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
| | - Jeremy P H Wong
- School of Life Sciences, Institute of Bioengineering and Global Health Institute, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
| | - Zainebe Al-Mayyah
- School of Life Sciences, Institute of Bioengineering and Global Health Institute, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
| | - Alexandre Persat
- School of Life Sciences, Institute of Bioengineering and Global Health Institute, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
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2
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Marino D, Peeters N, Rivas S. Ubiquitination during plant immune signaling. PLANT PHYSIOLOGY 2012; 160:15-27. [PMID: 22689893 PMCID: PMC3440193 DOI: 10.1104/pp.112.199281] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2012] [Accepted: 06/09/2012] [Indexed: 05/18/2023]
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3
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Rivas S, Genin S. A plethora of virulence strategies hidden behind nuclear targeting of microbial effectors. FRONTIERS IN PLANT SCIENCE 2011; 2:104. [PMID: 22639625 PMCID: PMC3355726 DOI: 10.3389/fpls.2011.00104] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2011] [Accepted: 12/09/2011] [Indexed: 05/24/2023]
Abstract
Plant immune responses depend on the ability to couple rapid recognition of the invading microbe to an efficient response. During evolution, plant pathogens have acquired the ability to deliver effector molecules inside host cells in order to manipulate cellular and molecular processes and establish pathogenicity. Following translocation into plant cells, microbial effectors may be addressed to different subcellular compartments. Intriguingly, a significant number of effector proteins from different pathogenic microorganisms, including viruses, oomycetes, fungi, nematodes, and bacteria, is targeted to the nucleus of host cells. In agreement with this observation, increasing evidence highlights the crucial role played by nuclear dynamics, and nucleocytoplasmic protein trafficking during a great variety of analyzed plant-pathogen interactions. Once in the nucleus, effector proteins are able to manipulate host transcription or directly subvert essential host components to promote virulence. Along these lines, it has been suggested that some effectors may affect histone packing and, thereby, chromatin configuration. In addition, microbial effectors may either directly activate transcription or target host transcription factors to alter their regular molecular functions. Alternatively, nuclear translocation of effectors may affect subcellular localization of their cognate resistance proteins in a process that is essential for resistance protein-mediated plant immunity. Here, we review recent progress in our field on the identification of microbial effectors that are targeted to the nucleus of host plant cells. In addition, we discuss different virulence strategies deployed by microbes, which have been uncovered through examination of the mechanisms that guide nuclear localization of effector proteins.
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Affiliation(s)
- Susana Rivas
- Institut National de la Recherche Agronomique, Laboratoire des Interactions Plantes-MicroorganismesUMR 441, Castanet-Tolosan, France
- Centre National de la Recherche Scientifique, Laboratoire des Interactions Plantes-MicroorganismesUMR 2594, Castanet-Tolosan, France
| | - Stéphane Genin
- Institut National de la Recherche Agronomique, Laboratoire des Interactions Plantes-MicroorganismesUMR 441, Castanet-Tolosan, France
- Centre National de la Recherche Scientifique, Laboratoire des Interactions Plantes-MicroorganismesUMR 2594, Castanet-Tolosan, France
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4
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Perrett CA, Lin DYW, Zhou D. Interactions of bacterial proteins with host eukaryotic ubiquitin pathways. Front Microbiol 2011; 2:143. [PMID: 21772834 PMCID: PMC3131157 DOI: 10.3389/fmicb.2011.00143] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2011] [Accepted: 06/16/2011] [Indexed: 12/20/2022] Open
Abstract
Ubiquitination is a post-translational modification in which one or more 76 amino acid polypeptide ubiquitin molecules are covalently linked to the lysine residues of target proteins. Ubiquitination is the main pathway for protein degradation that governs a variety of eukaryotic cellular processes, including the cell-cycle, vesicle trafficking, antigen presentation, and signal transduction. Not surprisingly, aberrations in the system have been implicated in the pathogenesis of many diseases including inflammatory and neurodegenerative disorders. Recent studies have revealed that viruses and bacterial pathogens exploit the host ubiquitination pathways to gain entry and to aid their survival/replication inside host cells. This review will summarize recent developments in understanding the biochemical and structural mechanisms utilized by bacterial pathogens to interact with the host ubiquitination pathways.
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Affiliation(s)
| | - David Yin-Wei Lin
- Department of Biological Sciences, Purdue UniversityWest Lafayette, IN, USA
| | - Daoguo Zhou
- Department of Biological Sciences, Purdue UniversityWest Lafayette, IN, USA
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5
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Price CTD, Kwaik YA. Exploitation of Host Polyubiquitination Machinery through Molecular Mimicry by Eukaryotic-Like Bacterial F-Box Effectors. Front Microbiol 2010; 1:122. [PMID: 21687758 PMCID: PMC3109402 DOI: 10.3389/fmicb.2010.00122] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2010] [Accepted: 10/12/2010] [Indexed: 11/13/2022] Open
Abstract
Microbial pathogens have evolved exquisite mechanisms to interfere and intercept host biological processes, often through molecular mimicry of specific host proteins. Ubiquitination is a highly conserved eukaryotic post-translational modification essential in determining protein fate, and is often hijacked by pathogenic bacteria. The conserved SKP1/CUL1/F-box (SCF) E3 ubiquitin ligase complex plays a key role in ubiquitination of proteins in eukaryotic cells. The F-box protein component of the SCF complex provides specificity to ubiquitination by binding to specific cellular proteins, targeting them to be ubiquitinated by the SCF complex. The bacterial pathogens. Legionella pneumophila, Agrobacterium tumefaciens, and Ralstonia solanacearum utilize type III or IV translocation systems to inject into the host cell eukaryotic-like F-box effectors that interact with the host SKP1 component of the SCF complex to trigger ubiquitination of specific host cells targets, which is essential to promote proliferation of these pathogens. Our bioinformatic analyses have identified at least 74 genes encoding putative F-box proteins belonging to 22 other bacterial species, including human pathogens, plant pathogens, and amebal endosymbionts. Therefore, subversion of the host ubiquitination machinery by bacterial F-box proteins may be a widespread strategy amongst pathogenic bacteria. The findings that bacterial F-box proteins harbor Ankyrin repeats as protein–protein interaction domains, which are present in F-box proteins of primitive but not higher eukaryotes, suggest acquisition of many bacterial F-box proteins from primitive eukaryotic hosts rather than the mammalian host.
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Affiliation(s)
- Christopher T D Price
- Department of Microbiology and Immunology, College of Medicine, University of Louisville Louisville, KY, USA
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6
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Liu Y, Kong X, Pan J, Li D. VIP1: linking Agrobacterium-mediated transformation to plant immunity? PLANT CELL REPORTS 2010; 29:805-812. [PMID: 20473505 DOI: 10.1007/s00299-010-0870-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2010] [Revised: 05/04/2010] [Accepted: 05/05/2010] [Indexed: 05/29/2023]
Abstract
Agrobacterium tumefaciens is the most efficient vehicle used today for the production of transgenic plants and plays an essential role in basic scientific research and in agricultural biotechnology. Previously, plant VirE2-interacting protein 1 (VIP1) was shown to play a role in Agrobacterium-mediated transformation. Recent reports demonstrate that VIP1, as one of the bZIP transcription factors, is also involved in plant immunity responses. Agrobacterium is able to activate and abuse VIP1 for transformation. These findings highlight Agrobacterium-host interaction and unveil how Agrobacterium hijacks host cellular mechanism for its own benefit. This review focuses on the roles played by VIP1 in Agrobacterium-mediated transformation and plant immunity.
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Affiliation(s)
- Yukun Liu
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, 61 DaiZong Street, Tai'an, 271018, Shandong, China
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7
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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.
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Zaltsman A, Krichevsky A, Loyter A, Citovsky V. Agrobacterium induces expression of a host F-box protein required for tumorigenicity. Cell Host Microbe 2010; 7:197-209. [PMID: 20227663 PMCID: PMC3427693 DOI: 10.1016/j.chom.2010.02.009] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2008] [Revised: 08/24/2009] [Accepted: 02/22/2010] [Indexed: 10/19/2022]
Abstract
Agrobacterium exports DNA into plant cells, eliciting neoplastic growths on many plant species. During this process, a Skp1-Cdc53-cullin-F-box (SCF) complex that contains the bacterial virulence F-box protein VirF facilitates genetic transformation by targeting for proteolysis proteins, the Agrobacterium protein VirE2 and the host protein VIP1, that coat the transferred DNA. However, some plant species do not require VirF for transformation. Here, we show that Agrobacterium induces expression of a plant F-box protein, which we designated VBF for VIP1-binding F-box protein, that can functionally replace VirF, regulating levels of the VirE2 and VIP1 proteins via a VBF-containing SCF complex. When expressed in Agrobacterium and exported into the plant cell, VBF functionally complements tumor formation by a strain lacking VirF. VBF expression is known to be induced by diverse pathogens, suggesting that Agrobacterium has co-opted a plant defense response and that bacterial VirF and plant VBF both contribute to targeted proteolysis that promotes plant genetic transformation.
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Affiliation(s)
- Adi Zaltsman
- Department of Biochemistry and Cell Biology, State University of New York, Stony Brook, NY 11794-5215
| | - Alexander Krichevsky
- Department of Biochemistry and Cell Biology, State University of New York, Stony Brook, NY 11794-5215
| | - Abraham Loyter
- Department of Biological Chemistry, Hebrew University of Jerusalem, 91904 Jerusalem, Israel
| | - Vitaly Citovsky
- Department of Biochemistry and Cell Biology, State University of New York, Stony Brook, NY 11794-5215
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9
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Krastanova SV, Balaji V, Holden MR, Sekiya M, Xue B, Momol EA, Burr TJ. Resistance to crown gall disease in transgenic grapevine rootstocks containing truncated virE2 of Agrobacterium. Transgenic Res 2010; 19:949-58. [PMID: 20182792 DOI: 10.1007/s11248-010-9373-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2009] [Accepted: 01/29/2010] [Indexed: 11/24/2022]
Abstract
A truncated form of the Ti-plasmid virE2 gene from Agrobacterium tumefaciens strains C58 and A6, and A. vitis strain CG450 was transferred and expressed in somatic embryos of grapevine rootstocks 110 Richter (Vitis rupestris × V. berlandieri), 3309 Couderc (V. rupestris × V. riparia) and Teleki 5C (V. berlandieri × V. riparia) via Agrobacterium-mediated transformation to confer resistance to crown gall disease. Transformation was confirmed in 98% of the 322 lines by enzyme-linked immunosorbent assay for the neomycin phosphotransferase II protein and 97% of 295 lines by polymerase chain reaction for the truncated virE2 transgene. Southern blot analysis revealed the insertion of truncated virE2 at one to three loci in a subset of seven transgenic 110 Richter lines. In vitro resistance screening assays based on inoculations of shoot internode sections showed reduced tumorigenicity and very small galls in 23 of 154 transgenic lines. Non-transformed controls had a 100% tumorigenicity rate with very large galls. Disease resistance assay at the whole plant level in the greenhouse revealed seven transgenic lines (3 lines of 110 Richter, 2 lines of 3309 Couderc and 2 lines of Teleki 5C) were resistant to A. tumefaciens strain C58 and A. vitis strains TM4 and CG450 with a substantially reduced percentage of inoculation sites showing gall as compared to controls. No association was found between the level of resistance to crown gall disease and the source Agrobacterium strain of virE2. Taken together, our data showed that resistance to crown gall disease can be achieved by expressing a truncated form of virE2 in grapevines.
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Affiliation(s)
- Stoyanka V Krastanova
- Department of Plant Pathology and Plant-Microbe Biology, Cornell University, New York State Agricultural Experiment Station, Geneva, NY 14456, USA
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10
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Zale JM, Agarwal S, Loar S, Steber CM. Evidence for stable transformation of wheat by floral dip in Agrobacterium tumefaciens. PLANT CELL REPORTS 2009; 28:903-13. [PMID: 19308413 PMCID: PMC2688021 DOI: 10.1007/s00299-009-0696-0] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2008] [Revised: 01/12/2009] [Accepted: 02/08/2009] [Indexed: 05/18/2023]
Abstract
Hexaploid wheat, one of the world's most important staple crops, remains a challenge for genetic transformation. We are developing a floral transformation protocol for wheat that does not require tissue culture. This paper presents three transformants in the hard red germplasm line Crocus that have been characterized thoroughly at the molecular level over three to six generations. Wheat spikes at the early boot stage, i.e. the early, mid or late uninucleate microspore stages, were immersed in an infiltration medium of strain C58C1 harboring pDs(Hyg)35S, or strain AGL1 harboring pBECKSred. pDs(Hyg)35S contains the NPTII and hph selectable markers, and transformants were detected using paromomycin spray at the whole plant level, NPTII ELISAs, or selection on medium with hygromycin. Strain AGL1, harboring pBECKSred, which contains the maize anthocyanin regulators, Lc and C1, and the NPTII gene, was also used to produce a Crocus transformant. T1 and T2 seeds with red embryos were selected; T1 and T2 plants were screened by sequential tests for paromomycin resistance and NPTII ELISAs. The transformants were low copy number and showed Mendelian segregation in the T2. Stable transmission of the transgenes over several generations has been demonstrated using Southern analysis. Gene expression in advanced progeny was shown using Reverse Transcriptase-PCR and ELISA assays for NPTII protein expression. This protocol has the potential to reduce the time and expense required for wheat transformation.
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Affiliation(s)
- Janice M Zale
- Plant Sciences Department, The University of Tennessee, 2431 Joe Johnson Drive, Knoxville, TN, 37996-4561, USA.
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11
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Citovsky V, Kapelnikov A, Oliel S, Zakai N, Rojas MR, Gilbertson RL, Tzfira T, Loyter A. Protein interactions involved in nuclear import of the Agrobacterium VirE2 protein in vivo and in vitro. J Biol Chem 2004; 279:29528-33. [PMID: 15123622 DOI: 10.1074/jbc.m403159200] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Agrobacterium, the only known organism capable of trans-kingdom DNA transfer, genetically transforms plants by transferring a segment of its DNA, T-DNA, into the nucleus of the host cell where it integrates into the plant genome. One of the central events in this genetic transformation process is nuclear import of the T-DNA molecule, which to a large degree is mediated by the bacterial virulence protein VirE2. VirE2 is distinguished by its nuclear targeting, which occurs only in plant but not in animal cells and is facilitated by the cellular VIP1 protein. The molecular mechanism of the VIP1 function is still unclear. Here, we used in vitro assays for nuclear import and quantification of protein-protein interactions to directly demonstrate formation of ternary complexes between VirE2, VIP1, and a component of the cellular nuclear import machinery, karyopherin alpha. Our results indicate that VIP1 functions as a molecular bridge between VirE2 and karyopherin alpha, allowing VirE2 to utilize the host cell nuclear import machinery even without being directly recognized by its components.
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Affiliation(s)
- Vitaly Citovsky
- Department of Biochemistry and Cell Biology, State University of New York at Stony Brook, Stony Brook, New York 11794-5215, USA.
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12
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Tzfira T, Vaidya M, Citovsky V. Increasing plant susceptibility to Agrobacterium infection by overexpression of the Arabidopsis nuclear protein VIP1. Proc Natl Acad Sci U S A 2002; 99:10435-40. [PMID: 12124400 PMCID: PMC124932 DOI: 10.1073/pnas.162304099] [Citation(s) in RCA: 107] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2002] [Indexed: 12/21/2022] Open
Abstract
Agrobacterium is a unique model system as well as a major biotechnological tool for genetic manipulation of plant cells. It is still unknown, however, whether host cellular factors exist that are limiting for infection, and whether their overexpression in plant cells can increase the efficiency of the infection. Here, we examined the effect of overexpression in tobacco plants of an Arabidopsis gene, VIP1, which encodes a recently discovered cellular protein required for Agrobacterium infection. Our results indicate that VIP1 is imported into the plant cell nucleus via the karyopherin alphadependent pathway and that elevated intracellular levels of VIP1 render the host plants significantly more susceptible to transient and stable genetic transformation by Agrobacterium, probably because of the increased nuclear import of the transferred-DNA.
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Affiliation(s)
- Tzvi Tzfira
- Department of Biochemistry and Cell Biology, State University of New York, Stony Brook, NY 11794-5215, USA
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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.
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Affiliation(s)
- A Krishnamohan
- Department of Plant Biotechnology, School of Biotechnology, Madurai Kamaraj University, Madurai 625 021, Tamil Nadu, India
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14
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Belogurov AA, Delver EP, Agafonova OV, Belogurova NG, Lee LY, Kado CI. Antirestriction protein Ard (Type C) encoded by IncW plasmid pSa has a high similarity to the "protein transport" domain of TraC1 primase of promiscuous plasmid RP4. J Mol Biol 2000; 296:969-77. [PMID: 10686096 DOI: 10.1006/jmbi.1999.3493] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The IncW plasmid pSa contains the gene ard encoding an antirestriction function that is specific for type I restriction and modification systems. The nucleotide sequence of ard was determined and an appropriate polypeptide of about 33 kDa was identified in Escherichia coli T7 expression system. Analysis of deduced amino acid sequence of Ard encoded by pSa revealed that this protein has no significant similarities with the known Ard proteins (ArdA and ArdB types) except the "antirestriction" motif (14 amino acid residues in length) conserved for all known Ard proteins. This finding suggests that pSa Ard may be classified as a new type of Ard proteins which we designated ArdC. The remarkable feature of ArdC is that it has a high degree of similarity (about 38 % identity) to the N-terminal region of RP4 TraC1 primase which includes about 300 amino acid residues and seems to be essential for binding to the single-stranded DNA and TraC1 protein transport to the recipient cells during the conjugal transfer of plasmid DNA. ArdC also binds to single-stranded DNA. In addition, this protein is able in vitro to protect the single-stranded but not double-stranded plasmid DNA against the activity of type II restriction endonuclease HhaI that cleaves both single and double-stranded DNA. We suggest that like TraC1, ArdC would be transported as a result of their interaction with the single-stranded DNA of transferred plasmid strand during conjugative passage through the cell envelope to the recipient bacterium. Such properties of ArdC protein might be useful to protect immediately the incoming single-stranded DNA from the host endonucleases.
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Affiliation(s)
- A A Belogurov
- Department of Genetic Engineering, National Cardiological Research and Development Center, Moscow, 121552, Russia.
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15
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Kalogeraki VS, Zhu J, Stryker JL, Winans SC. The right end of the vir region of an octopine-type Ti plasmid contains four new members of the vir regulon that are not essential for pathogenesis. J Bacteriol 2000; 182:1774-8. [PMID: 10692388 PMCID: PMC94480 DOI: 10.1128/jb.182.6.1774-1778.2000] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We sequenced the virD-virE, virE-virF, and virF-T-DNA intergenic regions of an octopine Ti plasmid. Four newly described genes were induced by the vir gene inducer acetosyringone, two of which are conserved in the nopaline-type Ti plasmid pTiC58. One gene resembles a family of phosphatase genes. Each of these genes is dispensable for tumorigenesis.
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Affiliation(s)
- V S Kalogeraki
- Department of Microbiology, Cornell University, Ithaca, New York, 14853, USA
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16
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Sundberg CD, Ream W. The Agrobacterium tumefaciens chaperone-like protein, VirE1, interacts with VirE2 at domains required for single-stranded DNA binding and cooperative interaction. J Bacteriol 1999; 181:6850-5. [PMID: 10542192 PMCID: PMC94155 DOI: 10.1128/jb.181.21.6850-6855.1999] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Agrobacterium tumefaciens transfers single-stranded DNA (ssDNA) into plants. Efficient tumorigenesis requires VirE1-dependent export of ssDNA-binding (SSB) protein VirE2. VirE1 binds VirE2 domains involved in SSB and self-association, and VirE1 may facilitate VirE2 export by preventing VirE2 aggregation and the premature binding of VirE2 to ssDNA.
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Affiliation(s)
- C D Sundberg
- Program in Genetics, Oregon State University, Corvallis, Oregon 97331, USA
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17
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Citovsky V, Guralnick B, Simon MN, Wall JS. The molecular structure of agrobacterium VirE2-single stranded DNA complexes involved in nuclear import. J Mol Biol 1997; 271:718-27. [PMID: 9299322 DOI: 10.1006/jmbi.1997.1230] [Citation(s) in RCA: 77] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Nuclear import of DNA is a central event in genetic transformation of plant cells by Agrobacterium tumefaciens. Agrobacterium elicits tumors on plant hosts by transporting a single-stranded (ss) copy of the bacterial transferred DNA (T-DNA) from its Ti (tumor-inducing) plasmid into the plant cell nucleus. Presumably, the process of T-DNA nuclear import is mediated by two agrobacterium proteins, VirD2 and VirE2, which are thought to directly associate with the transported T-DNA. Both proteins have been shown to contain functional nuclear localizations signals (NLS). Recently, VirE2 alone has been shown to actively transport ssDNA into the plant cell nucleus. To understand the process of DNA nuclear import, it is important to know the structure of the transport intermediate. To this end, complexes of VirE2 and ssDNA were analyzed by scanning transmission electron microscopy (STEM). This analysis suggests that VirE2 packages ssDNA into semi-rigid, hollow cylindrical filaments with a telephone cord-like coiled structure. The outer diameter of these complexes is too large to enter the nucleus by diffusion but is within the size exclusion limits of the active nuclear import. Detailed mass analysis of VirE2-ssDNA filaments is presented and a structural model is proposed.
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MESH Headings
- Agrobacterium tumefaciens/chemistry
- Bacterial Proteins/chemistry
- Bacterial Proteins/metabolism
- Bacterial Proteins/ultrastructure
- Biological Transport, Active
- Cell Nucleus/metabolism
- DNA, Bacterial/chemistry
- DNA, Bacterial/metabolism
- DNA, Bacterial/ultrastructure
- DNA, Single-Stranded/chemistry
- DNA, Single-Stranded/metabolism
- DNA, Single-Stranded/ultrastructure
- DNA-Binding Proteins/chemistry
- DNA-Binding Proteins/metabolism
- DNA-Binding Proteins/ultrastructure
- Image Processing, Computer-Assisted
- Ion Channels
- Macromolecular Substances
- Microscopy, Electron, Scanning Transmission
- Nucleic Acid Conformation
- Protein Binding
- Protein Conformation
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Affiliation(s)
- V Citovsky
- Department of Biochemistry and Cell Biology, State University of New York, Stony Brook, NY 11794-5215, USA
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CIRVILLERI G, LINDOW SE. Differential expression of genes of Pseudomonas syringae on leaves and in culture evaluated with random genomic lux fusions. Mol Ecol 1994. [DOI: 10.1111/j.1365-294x.1994.tb00058.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Lin TS, Kado CI. The virD4 gene is required for virulence while virD3 and orf5 are not required for virulence of Agrobacterium tumefaciens. Mol Microbiol 1993; 9:803-12. [PMID: 8231811 DOI: 10.1111/j.1365-2958.1993.tb01739.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The virD operon of the resident Ti plasmid of Agrobacterium tumefaciens contains loci involved in T-DNA processing and undefined virulence functions. Nucleotide sequence of the entire virD operon of pTiC58 revealed similarities to the virD operon of the root-inducing plasmid pRiA4b and to that of the octopine-type plasmid pTiA6NC. However, comparative sequence data show that virD of pTiC58 is more akin to that of the pRiA4b than to that of the pTiA6NC. T7f10::virD gene fusions were used to generate polypeptides that confirm the presence of four open reading frames virD1, virD2, virD3, and virD4 within virD which have a coding capacity for proteins of 16.1, 49.5, 72.6, and 73.5 kDa, respectively. virD3 therefore encodes a polypeptide 3.4 times larger (72.6 versus 21.3 kDa) than that encoded by virD3 of octopine Ti plasmids. Non-polar virD4 mutants could not be complemented by a distant homologue, TraG protein of plasmid RP4. An independently regulated fifth ORF (orf5) is located immediately downstream of 3' end of virD4 and encodes a polypeptide of 97.4 kDa. The expression of orf5 is dependent on its own promoter and is independent of acetosyringone induction in A. tumefaciens. Recently, it has been shown that virD3 of octopine Ri or Ti plasmids is not required for virulence. In this report, we confirm and extend these findings on a nopaline Ti plasmid by using several virD non-polar mutants that were tested for virulence. virD3 and orf5 non-polar mutants showed no effect on tumorigenicity on 14 different plant species, while virD4 mutants lost their tumorigenicity completely on all these test plants. These data suggest that virD3 and orf5 are not essential for virulence whereas virD4 is absolutely required on a wide range of host plants.
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Affiliation(s)
- T S Lin
- Davis Crown Gall Group, University of California, Davis 95616
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20
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Citovsky V, McLean BG, Zupan JR, Zambryski P. Phosphorylation of tobacco mosaic virus cell-to-cell movement protein by a developmentally regulated plant cell wall-associated protein kinase. Genes Dev 1993; 7:904-10. [PMID: 7684009 DOI: 10.1101/gad.7.5.904] [Citation(s) in RCA: 137] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
In host plants, cell-to-cell spread of tobacco mosaic virus (TMV) presumably occurs through intercellular connections, the plasmodesmata. TMV movement is mediated by a specific virus-encoded single-strand nucleic acid-binding protein, P30. The mechanism by which P30 operates is largely unknown. Here, we demonstrate that P30 expressed in transgenic plants is a phosphoprotein. We have developed an assay for in vitro phosphorylation of purified P30 by plant cell wall fractions and have localized the phosphorylation sites to amino acid residues Ser-258, Thr-261, and Ser-265. Interestingly, the P30 phosphorylation sites do not correspond to any known consensus phosphorylation sites for protein kinases. While P30 binding to single-stranded DNA (ssDNA) was shown to involve Thr-261, phosphorylation of this residue does not appear to play a role in binding activity. The protein kinase activity contained in the cell wall fractions was developmentally regulated, expressed predominantly in leaves. Within a leaf, this protein kinase activity increased with leaf maturation and correlated with the reported development of secondary plasmodesmata, sites of P30 accumulation. We suggest that phosphorylation may represent a mechanism for the host plant to sequester P30 following its localization to cell walls.
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Affiliation(s)
- V Citovsky
- Department of Plant Biology, University of California, Berkeley 94720
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21
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Meighen EA, Dunlap PV. Physiological, biochemical and genetic control of bacterial bioluminescence. Adv Microb Physiol 1993; 34:1-67. [PMID: 8452091 DOI: 10.1016/s0065-2911(08)60027-2] [Citation(s) in RCA: 114] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Affiliation(s)
- E A Meighen
- Department of Biochemistry, McGill University, Montreal, Quebec, Canada
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22
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Enhanced stable expression of aVibrio luciferase under the control of the Ω-translational enhancer in transgenic plants. World J Microbiol Biotechnol 1992; 8:638-44. [PMID: 24425616 DOI: 10.1007/bf01238805] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/1992] [Accepted: 07/03/1992] [Indexed: 10/25/2022]
Abstract
A fusion gene usingluxA andluxB genes ofVibrio species has been designed to express light autonomously in plants.LuxA:luxB was introduced into plants by a high-efficiency transformation system consisting of a high-copy virulence helper plasmid pUCD2614 and T-vector pUCD2715 containingluxA:luxB. The expression ofluxA:luxB fusion gene was optimized by adjusting the spacing between the genes and by placing the translational efficiency of its mRNA under the control of the Ω-3 translational enhancer. The resulting transgenic plants synthesized luciferase at levels greater than 1% of the total leaf protein. These plants produced light autonomously and light intensity was enhanced by the addition of aldehyde. That theluxA:luxB fusion has been optimized enables its use as a reporter for gene activity in plants during development and under various stress-inducing conditions. These results show that a specific protein from an introduced foreign gene can be produced with high efficiency in cultivated plants and such a system is therefore amenable for production of desired proteins through conventional farming methods.
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Citovsky V, Zupan J, Warnick D, Zambryski P. Nuclear localization of Agrobacterium VirE2 protein in plant cells. Science 1992; 256:1802-5. [PMID: 1615325 DOI: 10.1126/science.1615325] [Citation(s) in RCA: 238] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The Agrobacterium single-stranded DNA (ssDNA) intermediate T-strand is likely transferred to the plant cell nucleus as a complex with a single VirD2 molecule at its 5' end and multiple VirE2 molecules along its length. VirD2 contains a nuclear localization signal (NLS); however, because the T-strand is principally coated with VirE2 molecules, VirE2 also might assist in nuclear uptake. Indeed, VirE2 fused to a reporter protein localizes to plant cell nuclei, a process mediated by two amino acid sequences with homology to the bipartite NLS of Xenopus nucleoplasmin. Moreover, tumorigenicity of an avirulent virE2 mutant is restored when inoculated on transgenic plants expressing VirE2, supporting in planta function of VirE2.
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Affiliation(s)
- V Citovsky
- Department of Plant Biology, University of California, Berkeley 94720
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Citovsky V, Wong ML, Shaw AL, Prasad BV, Zambryski P. Visualization and characterization of tobacco mosaic virus movement protein binding to single-stranded nucleic acids. THE PLANT CELL 1992; 4:397-411. [PMID: 1379865 PMCID: PMC160140 DOI: 10.1105/tpc.4.4.397] [Citation(s) in RCA: 146] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Cell-to-cell spread of tobacco mosaic virus (TMV) is presumed to occur through plant intercellular connections, the plasmodesmata. Viral movement is an active process mediated by a specific virus-encoded P30 protein. P30 has at least two functions, to cooperatively bind single-stranded nucleic acids and to increase plasmodesmatal permeability. Here, we visualized P30 complexes with single-stranded DNA and RNA. These complexes are long, unfolded, and very thin (1.5 to 2.0 nm in diameter). Unlike TMV virions (300 x 18 nm), the complexes are compatible in size with the P30-induced increase in plasmodesmatal permeability (2.4 to 3.1 nm), making them likely candidates for the structures involved in the cell-to-cell movement of TMV. Mutational analysis using single and double deletion mutants of P30 revealed three regions potentially important for the protein function. Amino acid residues 65 to 86 possibly are required for correct folding of the active protein, and the regions between amino acid residues 112 to 185 and 185 to 268 potentially contain two independently active single-stranded nucleic acid binding domains designated binding domains A and B, respectively.
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Affiliation(s)
- V Citovsky
- Department of Plant Biology, University of California, Berkeley 94720
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25
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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.
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Affiliation(s)
- S C Winans
- Section of Microbiology, Cornell University, Ithaca, New York 14853
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Abstract
The cloning and expression of the lux genes from different luminescent bacteria including marine and terrestrial species have led to significant advances in our knowledge of the molecular biology of bacterial bioluminescence. All lux operons have a common gene organization of luxCDAB(F)E, with luxAB coding for luciferase and luxCDE coding for the fatty acid reductase complex responsible for synthesizing fatty aldehydes for the luminescence reaction, whereas significant differences exist in their sequences and properties as well as in the presence of other lux genes (I, R, F, G, and H). Recognition of the regulatory genes as well as diffusible metabolites that control the growth-dependent induction of luminescence (autoinducers) in some species has advanced our understanding of this unique regulatory mechanism in which the autoinducers appear to serve as sensors of the chemical or nutritional environment. The lux genes have now been transferred into a variety of different organisms to generate new luminescent species. Naturally dark bacteria containing the luxCDABE and luxAB genes, respectively, are luminescent or emit light on addition of aldehyde. Fusion of the luxAB genes has also allowed the expression of luciferase under a single promoter in eukaryotic systems. The ability to express the lux genes in a variety of prokaryotic and eukaryotic organisms and the ease and sensitivity of the luminescence assay demonstrate the considerable potential of the widespread application of the lux genes as reporters of gene expression and metabolic function.
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Affiliation(s)
- E A Meighen
- Department of Biochemistry, McGill University, Montreal, Quebec, Canada
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27
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Abstract
The asymmetric targeting of proteins to the Caulobacter predivisional cell poles yields dissimilar progeny. We show that the products of transcriptional reporter gene fusions to a flagellin gene and to the flagellar hook operon are segregated to the progeny swarmer cell. This segregation does not depend on sequences within the mRNA, but on the upstream regulatory region. The subset of developmentally regulated flagellar genes that exhibit mRNA segregation has the same upstream cis-acting elements: an activator-binding site known as the ftr sequence and an IHF-binding site. We propose that these genes are preferentially transcribed from the chromosome in the incipient swarmer cell pole of the predivisional cell.
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Dingwall A, Gober JW, Shapiro L. Identification of a Caulobacter basal body structural gene and a cis-acting site required for activation of transcription. J Bacteriol 1990; 172:6066-76. [PMID: 2211524 PMCID: PMC526931 DOI: 10.1128/jb.172.10.6066-6076.1990] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
The genes that encode the components and regulatory proteins of the Caulobacter crescentus flagellum are transcribed at specific times in the cell cycle. One of these genes, flbN, is required early in the flagellar assembly process. The flbN gene was cloned and sequenced, and the time of transcription activation was determined. The derived amino acid sequence indicates that fibN encodes a 25-kilodalton protein with a cleavable leader peptide. The flbN-encoded protein has 30.8% identity with the protein encoded by the Salmonella typhimurium basal body L-ring gene, flgH. Site-directed mutagenesis and gel mobility shift assays identified a binding site at -100 from the transcription start site for a trans-acting protein, RF-2, that functions to partially activate flbN transcription at a defined time in the cell cycle. The RF-2 binding region is similar to a NifA binding site normally used in the activation of some sigma 54 promoters involved in nitrogen fixation in other bacteria. Transcription of a flbN-reporter gene fusion in an Escherichia coli background was dependent on the presence of a NifA transcription factor supplied by a plasmid-borne Rhizobium meliloti gene encoding NifA. A deletion or base changes in the RF-2 binding region eliminated expression of the flbN gene in E. coli even when a NifA protein was provided in trans, suggesting that a sigma 54 promoter with an upstream activator element is used by the C. crescentus flbN gene. A consensus sequence for a sigma 54 promoter was found at the appropriate distance 5' to one of two identified transcription start sites. Site-directed mutagenesis confirmed that a conserved nucleotide in this sigma 54 promoter consensus sequence was required for transcription. Deletion of the region 5' to the apparent sigma 54 promoter caused a complete loss of transcription activation. Transcription activation of flbN in C. crescentus involves the combination of several elements: the NifA-like site is required for full activation, and other sequence elements 5' to the promoter and 3' to the transcription start site are necessary for the correct time of transcription initiation.
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Affiliation(s)
- A Dingwall
- Department of Developmental Biology, Beckman Center, Stanford University School of Medicine, California 94305-5427
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Kamoun S, Kado CI. A plant-inducible gene of Xanthomonas campestris pv. campestris encodes an exocellular component required for growth in the host and hypersensitivity on nonhosts. J Bacteriol 1990; 172:5165-72. [PMID: 2168373 PMCID: PMC213177 DOI: 10.1128/jb.172.9.5165-5172.1990] [Citation(s) in RCA: 62] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Using Tn4431, a transposon that allows transcriptional fusions to a promoterless luciferase (lux) operon, we have isolated a nonpathogenic mutant of Xanthomonas campestris pv. campestris, i.e., JS111, that does not incite any of the black rot symptoms on all tested cruciferous host plants (J. J. Shaw, L. G. Settles, and C. I. Kado, Mol. Plant Microbe Interact. 1:39-45, 1988). In the study reported here, we determined that in contrast to the wild-type strain, JS111 is unable to induce a hypersensitive necrotic response on nonhost plants such as datura, tomato, and cucumber, suggesting that JS111 is a nonpathogenic, nonhypersensitive Hrp mutant. JS111 displayed culture growth rates, exopolysaccharide production, and protease, pectate lysase, cellulase, amylase, and phosphatase activities comparable to those of the wild-type strain. However, the growth of JS111 in host leaves was markedly attenuated. Coinoculation of JS111 with the wild-type strain in cauliflower or radish leaves rescued the growth deficiency of the mutant to normal levels. The locus mutated in JS111 was cloned and named hrpXc, and transcriptional and genetic complementation analyses of the hrpXc locus were conducted. The regulation of hrpXc expression was also investigated in vitro and in planta, using fusions to a lux or chloramphenicol acetyltransferase reporter gene. The hrpXc gene was found to be strongly induced in radish leaves. This is the first report and analysis of a hrp locus from a Xanthomonas species.
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Affiliation(s)
- S Kamoun
- Department of Plant Pathology, University of California, Davis 95616
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Shirasu K, Morel P, Kado CI. Characterization of the virB operon of an Agrobacterium tumefaciens Ti plasmid: nucleotide sequence and protein analysis. Mol Microbiol 1990; 4:1153-63. [PMID: 2233252 DOI: 10.1111/j.1365-2958.1990.tb00690.x] [Citation(s) in RCA: 55] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The virulence regulon of the Agrobacterium tumefaciens TiC58 plasmid is composed of six operons, virA, virB, virG, virC, virD and virE, which direct the transfer of T-DNA into plant cells. The 9.5 kbp virB operon is the largest of these operons and its entire nucleotide sequence was determined and found to contain eleven open reading frames (ORFs). Gene fusions of each VirB ORF to T7 phi 10 were made and overexpressed in Escherichia coli to confirm that they encode proteins of predicted size. Hydrophobic analysis of these peptide sequences revealed nine proteins that contain hydrophobic spanning regions including signal-peptide-like sequences. These data suggest that the majority of VirB proteins may associate with bacterial cell membranes, while the two additional proteins possess a potential ATP-binding site. Strong homologies in amino acid sequences were observed between nopaline- and octopine-type plasmids. Specific differences in amino acid sequence encoded by VirB ORFs of nopaline and octopine Ti plasmid and a functional role of the gene products are discussed.
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Affiliation(s)
- K Shirasu
- Department of Plant Pathology, University of California, Davis 95616
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Gomes SL, Gober JW, Shapiro L. Expression of the Caulobacter heat shock gene dnaK is developmentally controlled during growth at normal temperatures. J Bacteriol 1990; 172:3051-9. [PMID: 2345134 PMCID: PMC209107 DOI: 10.1128/jb.172.6.3051-3059.1990] [Citation(s) in RCA: 84] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Caulobacter crescentus has a single dnaK gene that is highly homologous to the hsp70 family of heat shock genes. Analysis of the cloned and sequenced dnaK gene has shown that the deduced amino acid sequence could encode a protein of 67.6 kilodaltons that is 68% identical to the DnaK protein of Escherichia coli and 49% identical to the Drosophila and human hsp70 protein family. A partial open reading frame 165 base pairs 3' to the end of dnaK encodes a peptide of 190 amino acids that is 59% identical to DnaJ of E. coli. Northern blot analysis revealed a single 4.0-kilobase mRNA homologous to the cloned fragment. Since the dnaK coding region is 1.89 kilobases, dnaK and dnaJ may be transcribed as a polycistronic message. S1 mapping and primer extension experiments showed that transcription initiated at two sites 5' to the dnaK coding sequence. A single start site of transcription was identified during heat shock at 42 degrees C, and the predicted promoter sequence conformed to the consensus heat shock promoters of E. coli. At normal growth temperature (30 degrees C), a different start site was identified 3' to the heat shock start site that conformed to the E. coli sigma 70 promoter consensus sequence. S1 protection assays and analysis of expression of the dnaK gene fused to the lux transcription reporter gene showed that expression of dnaK is temporally controlled under normal physiological conditions and that transcription occurs just before the initiation of DNA replication. Thus, in both human cells (I. K. L. Milarski and R. I. Morimoto, Proc. Natl. Acad. Sci. USA 83:9517-9521, 1986) and in a simple bacterium, the transcription of a hsp70 gene is temporally controlled as a function of the cell cycle under normal growth conditions.
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Affiliation(s)
- S L Gomes
- Departamento de Bioquimica, Universidade de Sao Paulo, Brazil
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Rogowsky PM, Powell BS, Shirasu K, Lin TS, Morel P, Zyprian EM, Steck TR, Kado CI. Molecular characterization of the vir regulon of Agrobacterium tumefaciens: complete nucleotide sequence and gene organization of the 28.63-kbp regulon cloned as a single unit. Plasmid 1990; 23:85-106. [PMID: 2194232 DOI: 10.1016/0147-619x(90)90028-b] [Citation(s) in RCA: 65] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The entire vir regulon of Agrobacterium tumefaciens was subcloned and the complete 28.6-kbp nucleotide sequence was determined. The regulon was cloned as a single unit into two replicons, one of which replicates at a high copy number in this bacterium, and a second which has broad-host-range features to replicate in other Gram-negative bacteria. These vir region plasmids are able to confer in trans the processing and transfer activities on a second plasmid containing the T-DNA. In the high copy number vir region plasmid pUCD2614, a moderate increase in basal vir gene expression was observed as judged by virE::cat fusion expression assays relative to the wild-type control plasmid. Furthermore, higher efficiencies of tobacco leaf disk transformation were observed than with the widely used vir helper plasmid pAL4404. The nucleotide sequence studies showed that the vir region consists of 28,631 bp comprising 24 open reading frames which encode proteins involved in tumorigenicity. Two open reading frames not previously characterized, virH and ORF5, were uncovered within the virD/virE intervening spacer region. Together these studies more completely characterize the structure and function of the vir regulon.
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Affiliation(s)
- P M Rogowsky
- Department of Plant Pathology, University of California, Davis 95616
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Xu H, Dingwall A, Shapiro L. Negative transcriptional regulation in the Caulobacter flagellar hierarchy. Proc Natl Acad Sci U S A 1989; 86:6656-60. [PMID: 2771950 PMCID: PMC297904 DOI: 10.1073/pnas.86.17.6656] [Citation(s) in RCA: 63] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
The Caulobacter crescentus flagellum is formed at a specific time in the cell cycle and its assembly requires the ordered expression of a large number of genes. These genes are controlled in a positive trans-acting hierarchy that reflects the order of assembly of the flagellum. Using plasmids carrying transcriptional fusions of either a neo or a lux reporter gene to the promoters of three flagellar genes representing different ranks in the hierarchy (the hook operon, a basal body gene flbN, and the flaO gene), we have measured the level of chimeric gene expression in 13 flagellar mutant backgrounds. Mutants in the hook operon or in basal body genes caused overproduction of both hook operon and basal body gene chimeric mRNAs, suggesting that negative regulation is superimposed on the positive trans-acting control for these early events in the flagellar hierarchy. Mutants in the structural genes and in genes involved in flagellar assembly had no effect on flaO expression, placing the flaO gene near the top of the hierarchy. However, flaO expression appears to be under negative control by two regulatory genes flaS and flaW. Negative control, as a response to the completion of specific steps in the assembly process, may be an important mechanism used by the cell to turn off flagellar gene expression once the gene product is no longer needed.
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Affiliation(s)
- H Xu
- Department of Molecular Biology, Albert Einstein College of Medicine, Bronx, NY 10461
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34
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Morel P, Powell BS, Rogowsky PM, Kado CI. Characterization of the virA virulence gene of the nopaline plasmid, pTiC58, of Agrobacterium tumefaciens. Mol Microbiol 1989; 3:1237-46. [PMID: 2796735 DOI: 10.1111/j.1365-2958.1989.tb00274.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
We have determined the complete nucleotide sequence of a 4.8 kilobase fragment encompassing the virA locus of the nopaline-type plasmid, pTiC58, of Agrobacterium tumefaciens. virA is composed of a single open reading frame of 2499 nucleotides, capable of encoding a protein of 91.3 kiloDaltons. A trpE::virA gene fusion was used to confirm the reading frame of virA. High nucleotide and amino acid sequence homologies were observed between pTiC58 virA and the virA sequences of three octopine-type plasmids. Strong homologies in amino acid sequence were observed between pTiC58 VirA and seven bacterial proteins which control various regulons. Two hydrophobic domains within VirA are also consistent with a model in which VirA acts as a membrane-bound sensor of plant signal molecules.
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Affiliation(s)
- P Morel
- Davis Crown Gall Group, Department of Plant Pathology, University of California, Davis 95616
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35
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Bonnard G, Vincent F, Otten L. Sequence and distribution of IS866, a novel T region-associated insertion sequence from Agrobacterium tumefaciens. Plasmid 1989; 22:70-81. [PMID: 2550985 DOI: 10.1016/0147-619x(89)90037-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
We have identified a new insertion sequence, IS866, located in the auxin synthesis gene TA iaaH of Tm4, a wide host range biotype III octopine/cucumopine type Agrobacterium tumefaciens strain with two T regions on its tumor-inducing (Ti) plasmid, TA, and TB. IS866 is 2716 bp long, has inverted repeats of 27 bp with three mismatches, and generates 8-bp direct repeats upon integration. In addition to IS866, pTiTm4 carries two copies of a related element, IS867, associated with TA and TB, respectively. A systematic study of 92 virulent Agrobacterium strains has shown that among the three biotypes all octopine/cucumopine and vitopine biotype III isolates contain IS866-like elements. The various octopine/cucumopine Ti plasmids always carry IS866 and IS867 at the same position as in pTiTm4. The chromosomes of the bacteria which contain these Ti plasmids also carry IS866 and IS867 copies but in varying numbers and locations.
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Affiliation(s)
- G Bonnard
- Institut de Biologie Moléculaire des Plantes du CNRS, Strasbourg, France
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Grimsley N, Hohn B, Ramos C, Kado C, Rogowsky P. DNA transfer from Agrobacterium to Zea mays or Brassica by agroinfection is dependent on bacterial virulence functions. MOLECULAR & GENERAL GENETICS : MGG 1989; 217:309-16. [PMID: 2770696 DOI: 10.1007/bf02464898] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
DNA transfer from Agrobacterium tumefaciens, a soil bacterium, to the non-host graminaceous monocotyle-donous plant Zea mays, was analysed using the recently developed technique of agroinfection. Agroinfection of Z. mays with maize streak virus using strains of A. tumefaciens carrying mutations in the pTiC58 virulence region showed an almost absolute dependence on the products of the bacterial virC genes. In contrast, agroinfection of the control host Brassica rapa with cauliflower mosaic virus was less dependent on the virC gene products. In other respects, the basic mechanism of the plant-bacterium interaction was found to be similar. While intact virA, B, D and G functions were absolutely necessary, mutants in virE were attenuated. Agroinfection of maize was effective in the absence of an exogenously supplied vir gene inducer, and indeed wounded Z. mays tissues were found to produce substance(s) which induced the expression of A. tumefaciens vir genes. These findings are discussed in the light of current knowledge about the function of Agrobacterium vir genes.
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Affiliation(s)
- N Grimsley
- Friedrich Miescher-Institut, Basel, Switzerland
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Powell BS, Rogowsky PM, Kado CI. virG of Agrobacterium tumefaciens plasmid pTiC58 encodes a DNA-binding protein. Mol Microbiol 1989; 3:411-9. [PMID: 2664419 DOI: 10.1111/j.1365-2958.1989.tb00186.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Virulence genes of the Agrobacterium tumefaciens Ti plasmid are positively regulated by the products of virA and virG. To study the DNA-binding properties of the VirG protein, a translational fusion between virG and the trpE gene of Escherichia coli was constructed, and antiserum was raised against the encoded fusion protein. Using this antiserum, a protein of Mr congruent to 29,000, a size similar to that calculated from the virG nucleotide sequence, was detected in an E. coli strain harbouring a virG expression vector. Both the virG protein and the fusion protein were found, by filter-binding and gel retardation analyses, to bind DNA nonspecifically. These data support an existing model for the two-component regulatory systems of bacteria.
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Affiliation(s)
- B S Powell
- Department of Plant Pathology, University of California, Davis 95616
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Zambryski P, Tempe J, Schell J. Transfer and function of T-DNA genes from agrobacterium Ti and Ri plasmids in plants. Cell 1989; 56:193-201. [PMID: 2643473 DOI: 10.1016/0092-8674(89)90892-1] [Citation(s) in RCA: 170] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- P Zambryski
- Division of Molecular Plant Biology, University of California, Berkeley 94720
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Vernade D, Herrera-Estrella A, Wang K, Van Montagu M. Glycine betaine allows enhanced induction of the Agrobacterium tumefaciens vir genes by acetosyringone at low pH. J Bacteriol 1988; 170:5822-9. [PMID: 3192516 PMCID: PMC211688 DOI: 10.1128/jb.170.12.5822-5829.1988] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
We established growth conditions for efficient induction of the vir genes of Agrobacterium tumefaciens by acetosyringone. Optimal induction was attained at a pH below 5.2 in an AB minimal medium-derived high-osmotic-strength medium containing glycine betaine. This natural osmoprotectant accelerated the adaptation of the bacteria to these conditions. We established the kinetics of induction for virB, virD, virE, and virG by using lacZ fusions, and we found that the virB mutant strain could not adapt to this low-pH medium unless 1 mM CaCl2 was added. This pH control of vir gene expression was shown to act at the level of expression of virG, which was the limiting factor. This improved vir induction at a low pH correlated with an increase in a set of proteins which was analyzed by two-dimensional gel electrophoresis. The fact that high inducibility corresponded to a reduced growth rate and the demonstration that a set of proteins was associated with the inducible state suggest that vir gene induction is linked to the adaptation of the cells to an unfavorable environment. Hence, vir gene expression in A. tumefaciens is probably dependent upon a machinery which is specific to an adaptive response; the implications for plant transformation are discussed.
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Affiliation(s)
- D Vernade
- Laboratorium voor Genetica, Rijksuniversiteit Gent, Belgium
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Steck TR, Morel P, Kado CI. Vir box sequences in Agrobacterium tumefaciens pTiC58 and A6. Nucleic Acids Res 1988; 16:8736. [PMID: 3419938 PMCID: PMC338614 DOI: 10.1093/nar/16.17.8736] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Affiliation(s)
- T R Steck
- Department of Plant Pathology, University of California, Davis 95616
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Tait RC, Kado CI. Regulation of the virC and virD promoters of pTiC58 by the ros chromosomal mutation of Agrobacterium tumefaciens. Mol Microbiol 1988; 2:385-92. [PMID: 2840554 DOI: 10.1111/j.1365-2958.1988.tb00043.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The virC and virD operons of the virulence region of the Ti plasmid are highly regulated, requiring a transcriptional regulator that is encoded by virG and is activated by the product of virA and plant phenolics such as acetosyringone. Full expression of virC and virD of octopine and nopaline Ti plasmids is also obtained by a mutation in the ros gene of the Agrobacterium tumefaciens chromosome. S1-nuclease analysis, in vitro transcription, and DNase I protection experiments with A. tumefaciens RNA polymerase revealed virD promoters tandemly arranged, both of which are functional in the Ros mutant, while only one is functional in the presence of acetosyringone. A third (overlapping) promoter appears to be responsible for transcription of virC. Expression of virC and virD appears to be modulated by factors within the bacterium by means of a mechanism that is independent of factors produced during infection of the host plant.
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Affiliation(s)
- R C Tait
- Department of Plant Pathology, University of California, Davis 95616
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42
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Abstract
The virE operon of the Agrobacterium tumefaciens Ti plasmid pTiA6 encodes at least one trans-acting protein involved in the expression of virulence. Two open reading frames designated virE1 and virE2 code for polypeptides of 7 and 60 kilodaltons (kDa), respectively, that can be visualized after expression in Escherichia coli minicells. To determine which virE sequences are required for virulence, a strain deleted for the entire locus [strain KE1(pTiA6 delta E)] was constructed and tested for the ability to be complemented by subclones with and without site-directed mutations in the virE operon. One subclone containing only virE1 and virE2 as well as upstream promoter sequences was sufficient to restore full virulence on the host plant Kalanchoe daigremontiana. However, some other virulence locus representing a host range determinant appeared to be deleted from strain KE1(pTiA6 delta E), since virE1 and virE2 were not sufficient to fully restore virulence on wounded tomato plants. virE operon constructs with specific lesions in either virE1 or virE2 were impaired for complementation of pTiA6 delta E. Several mutations specific for the promoter-proximal virE1 locus appeared to have a polar effect on expression of the virE2-encoded 60-kDa protein. However, virE2::lacZ fusion constructs suggest that this effect is not at the level of transcription or translation. Collectively, these data indicate that both the 7- and the 60-kDa polypeptides are virulence determinants for the Ti plasmid pTiA6 and suggest that the 60-kDa protein may be less stable in the absence of the 7-kDa protein.
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Rogowsky PM, Close TJ, Chimera JA, Shaw JJ, Kado CI. Regulation of the vir genes of Agrobacterium tumefaciens plasmid pTiC58. J Bacteriol 1987; 169:5101-12. [PMID: 2822665 PMCID: PMC213914 DOI: 10.1128/jb.169.11.5101-5112.1987] [Citation(s) in RCA: 209] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
The virulence (vir) region of pTiC58 was screened for promoter activities by using gene fusions to a promoterless lux operon in the broad-host-range vector pUCD615. Active vir fragments contained the strongly acetosyringone-inducible promoters of virB, virC, virD, and virE and the weakly inducible promoters of virA and virG. Identical induction patterns were obtained with freshly sliced carrot disks, suggesting that an inducer is released after plant tissue is wounded. Optimal conditions for vir gene induction were pH 5.7 for 50 microM acetosyringone or sinapic acid. The induction of virB and virE by acetosyringone was strictly dependent on intact virA and virG loci. An increase in the copy number of virG resulted in a proportional, acetosyringone-independent increase in vir gene expression, and a further increase occurred only if an inducing compound and virA were present.
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Affiliation(s)
- P M Rogowsky
- Department of Plant Pathology, University of California, Davis 95616
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Powell BS, Powell GK, Morris RO, Rogowsky PM, Kado CI. Nucleotide sequence of the virG locus of the Agrobacterium tumefaciens plasmid pTiC58. Mol Microbiol 1987; 1:309-16. [PMID: 3448462 DOI: 10.1111/j.1365-2958.1987.tb01937.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The nucleotide sequence of the virG locus of the nopaline type plasmid pTiC58 of Agrobacterium tumefaciens has been determined. It contains an open reading frame (ORF) of 759 nucleotides and has 77% homology to the virG sequences of octopine type plasmids. Differences between the sequences of the two types of Ti plasmids in the region of virG are located predominantly outside the ORF. The amino acid sequences inferred from the two virG genes show 80% homology to each other and each shows the same moderate homologies to amino acid sequences derived from genes in a family of two-component regulatory systems. Specific differences in nucleotide and amino acid sequences as well as a structure-function model for the gene product are discussed.
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Affiliation(s)
- B S Powell
- Department of Plant Pathology, University of California, Davis 95616
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