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Ramos-Sánchez JM, Triozzi PM, Moreno-Cortés A, Conde D, Perales M, Allona I. Real-time monitoring of PtaHMGB activity in poplar transactivation assays. PLANT METHODS 2017; 13:50. [PMID: 28638438 PMCID: PMC5472981 DOI: 10.1186/s13007-017-0199-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2017] [Accepted: 06/08/2017] [Indexed: 05/06/2023]
Abstract
BACKGROUND Precise control of gene expression is essential to synchronize plant development with the environment. In perennial plants, transcriptional regulation remains poorly understood, mainly due to the long time required to perform functional studies. Transcriptional reporters based on luciferase have been useful to study circadian and diurnal regulation of gene expression, both by transcription factors and chromatin remodelers. The high mobility group proteins are considered transcriptional chaperones that also modify the chromatin architecture. They have been found in several species, presenting in some cases a circadian expression of their mRNA or protein. RESULTS Transactivation experiments have been shown as a powerful and fast method to obtain information about the potential role of transcription factors upon a certain reporter. We designed and validated a luciferase transcriptional reporter using the 5' sequence upstream ATG of Populus tremula × alba LHY2 gene. We showed the robustness of this reporter line under long day and continuous light conditions. Moreover, we confirmed that pPtaLHY2::LUC activity reproduces the accumulation of PtaLHY2 mRNA. We performed transactivation studies by transient expression, using the reporter line as a genetic background, unraveling a new function of a high mobility group protein in poplar, which can activate the PtaLHY2 promoter in a gate-dependent manner. We also showed PtaHMGB2/3 needs darkness to produce that activation and exhibits an active degradation after dawn, mediated by the 26S proteasome. CONCLUSIONS We generated a stable luciferase reporter poplar line based on the circadian clock gene PtaLHY2, which can be used to investigate transcriptional regulation and signal transduction pathway. Using this reporter line as a genetic background, we established a methodology to rapidly assess potential regulators of diurnal and circadian rhythms. This tool allowed us to demonstrate that PtaHMGB2/3 promotes the transcriptional activation of our reporter in a gate-dependent manner. Moreover, we added new information about the PtaHMGB2/3 protein regulation along the day. This methodology can be easily adapted to other transcription factors and reporters.
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Affiliation(s)
- José M. Ramos-Sánchez
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid (UPM) - Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), Campus Montegancedo UPM, 28223 Pozuelo de Alarcón, Madrid, Spain
| | - Paolo M. Triozzi
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid (UPM) - Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), Campus Montegancedo UPM, 28223 Pozuelo de Alarcón, Madrid, Spain
| | - Alicia Moreno-Cortés
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid (UPM) - Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), Campus Montegancedo UPM, 28223 Pozuelo de Alarcón, Madrid, Spain
| | - Daniel Conde
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid (UPM) - Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), Campus Montegancedo UPM, 28223 Pozuelo de Alarcón, Madrid, Spain
| | - Mariano Perales
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid (UPM) - Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), Campus Montegancedo UPM, 28223 Pozuelo de Alarcón, Madrid, Spain
| | - Isabel Allona
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid (UPM) - Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), Campus Montegancedo UPM, 28223 Pozuelo de Alarcón, Madrid, Spain
- Departamento de Biotecnología-Biología Vegetal, Escuela Técnica Superior Ingeniería Agronómica, Alimentaria y de Biosistemas, Universidad Politécnica de Madrid (UPM), 28040 Madrid, Spain
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The Interplay between Different Stability Systems Contributes to Faithful Segregation: Streptococcus pyogenes pSM19035 as a Model. Microbiol Spectr 2016; 2:PLAS-0007-2013. [PMID: 26104212 DOI: 10.1128/microbiolspec.plas-0007-2013] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
The Streptococcus pyogenes pSM19035 low-copy-number θ-replicating plasmid encodes five segregation (seg) loci that contribute to plasmid maintenance. These loci map outside of the minimal replicon. The segA locus comprises β2 recombinase and two six sites, and segC includes segA and also the γ topoisomerase and two ssiA sites. Recombinase β2 plays a role both in maximizing random segregation by resolving plasmid dimers (segA) and in catalyzing inversion between two inversely oriented six sites. segA, in concert with segC, facilitates replication fork pausing at ssiA sites and overcomes the accumulation of "toxic" replication intermediates. The segB1 locus encodes ω, ε, and ζ genes. The short-lived ε2 antitoxin and the long-lived ζ toxin form an inactive ζε2ζ complex. Free ζ toxin halts cell proliferation upon decay of the ε2 antitoxin and enhances survival. If ε2 expression is not recovered, by loss of the plasmid, the toxin raises lethality. The segB2 locus comprises δ and ω genes and six parS sites. Proteins δ2 and ω2, by forming complexes with parS and chromosomal DNA, pair the plasmid copies at the nucleoid, leading to the formation of a dynamic δ2 gradient that separates the plasmids to ensure roughly equal distribution to daughter cells at cell division. The segD locus, which comprises ω2 (or ω2 plus ω22) and parS sites, coordinates expression of genes that control copy number, better-than-random segregation, faithful partition, and antibiotic resistance. The interplay of the seg loci and with the rep locus facilitates almost absolute plasmid stability.
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Abstract
One of the disadvantages of circular plasmids and chromosomes is their high sensitivity to rearrangements caused by homologous recombination. Odd numbers of crossing-over occurring during or after replication of a circular replicon result in the formation of a dimeric molecule in which the two copies of the replicon are fused. If they are not converted back to monomers, the dimers of replicons may fail to correctly segregate at the time of cell division. Resolution of multimeric forms of circular plasmids and chromosomes is mediated by site-specific recombination, and the enzymes that catalyze this type of reaction fall into two families of proteins: the serine and tyrosine recombinase families. Here we give an overview of the variety of site-specific resolution systems found on circular plasmids and chromosomes.
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Genetic surgery in fungi: employing site-specific recombinases for genome manipulation. Appl Microbiol Biotechnol 2014; 98:1971-82. [DOI: 10.1007/s00253-013-5480-y] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2013] [Revised: 12/16/2013] [Accepted: 12/17/2013] [Indexed: 12/21/2022]
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Antosch M, Mortensen SA, Grasser KD. Plant proteins containing high mobility group box DNA-binding domains modulate different nuclear processes. PLANT PHYSIOLOGY 2012; 159:875-83. [PMID: 22585776 PMCID: PMC3387713 DOI: 10.1104/pp.112.198283] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
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Validation of a self-excising marker in the human pathogen Aspergillus fumigatus by employing the beta-rec/six site-specific recombination system. Appl Environ Microbiol 2010; 76:6313-7. [PMID: 20656854 DOI: 10.1128/aem.00882-10] [Citation(s) in RCA: 93] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Recyclable markers based on site-specific recombination allow repetitive gene targeting in filamentous fungi. Here we describe for the first time functionality of the bacterial recombination system employing beta serine recombinase acting on six recognition sequences (beta-rec/six) in a fungal host, the human pathogen Aspergillus fumigatus, and its use in establishing a self-excising resistance marker cassette for serial gene replacement.
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Plasmid pSM19035, a model to study stable maintenance in Firmicutes. Plasmid 2010; 64:1-17. [PMID: 20403380 DOI: 10.1016/j.plasmid.2010.04.002] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2010] [Revised: 04/09/2010] [Accepted: 04/13/2010] [Indexed: 12/15/2022]
Abstract
pSM19035 is a low-copy-number theta-replicating plasmid, which belongs to the Inc18 family. Plasmids of this family, which show a modular organization, are functional in evolutionarily diverse bacterial species of the Firmicutes Phylum. This review summarizes our understanding, accumulated during the last 20 years, on the genetics, biochemistry, cytology and physiology of the five pSM19035 segregation (seg) loci, which map outside of the minimal replicon. The segA locus plays a role both in maximizing plasmid random segregation, and in avoiding replication fork collapses in those plasmids with long inverted repeated regions. The segB1 locus, which acts as the ultimate determinant of plasmid maintenance, encodes a short-lived epsilon(2) antitoxin protein and a long-lived zeta toxin protein, which form a complex that neutralizes zeta toxicity. The cells that do not receive a copy of the plasmid halt their proliferation upon decay of the epsilon(2) antitoxin. The segB2 locus, which encodes two trans-acting, ParA- and ParB-like proteins and six cis-acting parS centromeres, actively ensures equal or roughly equal distribution of plasmid copies to daughter cells. The segC locus includes functions that promote the shift from the use of DNA polymerase I to the replicase (PolC-PolE DNA polymerases). The segD locus, which encodes a trans-acting transcriptional repressor, omega(2), and six cis-acting cognate sites, coordinates the expression of genes that control copy number, better-than-random segregation and partition, and assures the proper balance of these different functions. Working in concert the five different loci achieve almost absolute plasmid maintenance with a minimal growth penalty.
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Jang JY, Kwak KJ, Kang H. Expression of a high mobility group protein isolated from Cucumis sativus affects the germination of Arabidopsis thaliana under abiotic stress conditions. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2008; 50:593-600. [PMID: 18713428 DOI: 10.1111/j.1744-7909.2008.00650.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Although high mobility group B (HMGB) proteins have been identified from a variety of plant species, their importance and functional roles in plant responses to changing environmental conditions are largely unknown. Here, we investigated the functional roles of a CsHMGB isolated from cucumber (Cucumis sativus L.) in plant responses to environmental stimuli. Under normal growth conditions or when subjected to cold stress, no differences in plant growth were found between the wild-type and transgenic Arabidopsis thaliana overexpressing CsHMGB. By contrast, the transgenic Arabidopsis plants displayed retarded germination compared with the wild-type plants when grown under high salt or dehydration stress conditions. Germination of the transgenic plants was delayed by the addition of abscisic acid (ABA), implying that CsHMGB affects germination through an ABA-dependent way. The expression of CsHMGB had affected only the germination stage, and CsHMGB did not affect the seedling growth of the transgenic plants under the stress conditions. The transcript levels of several germination-responsive genes were modulated by the expression of CsHMGB in Arabidopsis. Taken together, these results suggest that ectopic expression of a CsHMGB in Arabidopsis modulates the expression of several germination-responsive genes, and thereby affects the germination of Arabidopsis plants under different stress conditions.
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Affiliation(s)
- Ji Young Jang
- Department of Plant Biotechnology, Agricultural Plant Stress Research Center, Biotechnology Research Institute, College of Agriculture and Life Sciences, Chonnam National University, Gwangju, Korea
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Grønlund JT, Stemmer C, Lichota J, Merkle T, Grasser KD. Functionality of the beta/six site-specific recombination system in tobacco and Arabidopsis: a novel tool for genetic engineering of plant genomes. PLANT MOLECULAR BIOLOGY 2007; 63:545-56. [PMID: 17131098 DOI: 10.1007/s11103-006-9108-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2006] [Accepted: 10/30/2006] [Indexed: 05/12/2023]
Abstract
The beta recombinase is a member of the prokaryotic site-specific serine recombinases (invertase/resolvase family), which in the presence of a DNA bending cofactor can catalyse DNA deletions between two directly oriented 90-bp six recombination sites. We have examined here whether the beta recombinase can be expressed in plants and whether it displays in planta its specific catalytic activity excising DNA sequences that are flanked by six sites. In plant protoplasts, the enzyme could be expressed as a GFP-beta recombinase fusion which can localise to the cell nucleus. Beta recombinase stably expressed in tobacco plants can catalyse deletion of a spacer region that is flanked by directly oriented six sites and has been placed between promoter and a GUS reporter gene (preventing GUS expression). In transient transformation experiments, beta recombinase-mediated elimination of the spacer results in transcriptional induction of the GUS gene. Similarly, beta recombinase in stably double-transformed Arabidopsis plants deletes specifically the spacer region of a reporter construct that has been incorporated into the genome. In the segregating T1 generation, plants were identified that contain exclusively the recombined reporter construct. In summary, our results demonstrate that functional / recombinase can be expressed in plants and that the enzyme is suitable to precisely eliminate undesired sequences from plant genomes. Therefore, the beta/six recombination system (and presumably related recombinases) may become an attractive tool for plant genetic engineering.
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Affiliation(s)
- Jesper T Grønlund
- Department of Life Sciences, Aalborg University, Sohngaardsholmsvej 49, DK-9000 Aalborg, Denmark
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Kwak KJ, Kim JY, Kim YO, Kang H. Characterization of Transgenic Arabidopsis Plants Overexpressing High Mobility Group B Proteins under High Salinity, Drought or Cold Stress. ACTA ACUST UNITED AC 2007; 48:221-31. [PMID: 17169924 DOI: 10.1093/pcp/pcl057] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
High mobility group B (HMGB) proteins found in the nuclei of higher eukaryotes play roles in various cellular processes such as replication, transcription and nucleosome assembly. The Arabidopsis thaliana genome contains eight genes encoding HMGB proteins, the functions of which remain largely unknown in the transcriptional regulation of plant stress responses. To understand better the functions of HMGB proteins in the responses of plants to environmental stimuli, we examined the effect of various abiotic stresses on germination and growth of transgenic Arabidopsis plants that overexpress a single isoform of HMGB. The expression of HMGB2, HMGB3 and HMGB4 was up-regulated by cold stress, whereas the expression of HMGB2 and HMGB3 was markedly down-regulated by drought or salt stress. Under salt or drought stress, the transgenic Arabidopsis plants that overexpress HMGB2 displayed retarded germination and subsequent growth compared with wild-type plants. Overexpression of HMGB4 had no impact on seed germination and seedling growth of the plants under the stress conditions tested. In contrast to no significant stress-related phenotypes of HMGB5-overexpressing plants, loss-of-function mutants of HMGB5 displayed retarded germination and subsequent growth compared with wild-type plants under stress conditions. Although transcript levels of various stress-responsive genes were not modulated by the expression of HMGB2, expression of several germination-responsive genes was modulated by HMGB2 under salt stress. Taken together, these results provide a novel basis for understanding the biological functions of HMGB protein family members that differently affect germination and seedling growth of Arabidopsis plants under various stress conditions.
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Affiliation(s)
- Kyung Jin Kwak
- Department of Plant Biotechnology, Agricultural Plant Stress Research Center and Biotechnology Research Institute, College of Agriculture and Life Sciences, Chonnam National University, Gwangju, 500-757 Korea
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Young Jang J, Jin Kwak K, Kang H. Molecular cloning of a cDNA encoding a high mobility group protein in Cucumis sativus and its expression by abiotic stress treatments. JOURNAL OF PLANT PHYSIOLOGY 2007; 164:205-8. [PMID: 16781795 DOI: 10.1016/j.jplph.2006.04.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2006] [Accepted: 04/13/2006] [Indexed: 05/10/2023]
Abstract
A cDNA encoding a high mobility group B (HMGB) protein was isolated from Cucumis sativus and characterized with respect to its sequence, expression and responses to various abiotic stress treatments. The predicted polypeptide of 146 amino acid residues contains characteristic features of HMGB family proteins including the N-terminal basic region, one HMG-box and a stretch of acidic amino acid residues at the C-terminus. In vitro nucleic acid-binding assay revealed that the HMGB protein bound to both single-stranded DNA and double-stranded DNA. DNA gel blot analysis indicated that the HMGB gene is a single copy gene in cucumber genome. RNA gel blot analysis showed that the cucumber HMGB was more abundantly expressed in the roots than in shoots and leaves. Various abiotic stresses, including cold, drought and high salinity, down regulated markedly the expression of the HMGB in cucumber. The present report identifies a novel gene encoding HMGB protein in cucumber that shows a significant response to abiotic stress treatments.
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Affiliation(s)
- Ji Young Jang
- Department of Plant Biotechnology and Agricultural Plant Stress Research Center, College of Agriculture and Life Sciences, Chonnam National University, Gwangju, Republic of Korea
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12
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Grasser KD, Launholt D, Grasser M. High mobility group proteins of the plant HMGB family: dynamic chromatin modulators. ACTA ACUST UNITED AC 2007; 1769:346-57. [PMID: 17316841 DOI: 10.1016/j.bbaexp.2006.12.004] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2006] [Revised: 12/29/2006] [Accepted: 12/31/2006] [Indexed: 12/13/2022]
Abstract
In plants, the chromosomal high mobility group (HMG) proteins of the HMGB family typically contain a central HMG-box DNA-binding domain that is flanked by a basic N-terminal and an acidic C-terminal domain. The HMGB proteins are abundant and highly mobile proteins in the cell nucleus that influence chromatin structure and enhance the accessibility of binding sites to regulatory factors. Due to their remarkable DNA bending activity, HMGB proteins can increase the structural flexibility of DNA, promoting the assembly of nucleoprotein complexes that control DNA-dependent processes including transcription. Therefore, members of the HMGB family act as versatile modulators of chromatin function.
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Affiliation(s)
- Klaus D Grasser
- Department of Life Sciences, Aalborg University, Sohngaardsholmsvej 49, DK-9000 Aalborg, Denmark.
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Pohjoismäki JLO, Wanrooij S, Hyvärinen AK, Goffart S, Holt IJ, Spelbrink JN, Jacobs HT. Alterations to the expression level of mitochondrial transcription factor A, TFAM, modify the mode of mitochondrial DNA replication in cultured human cells. Nucleic Acids Res 2006; 34:5815-28. [PMID: 17062618 PMCID: PMC1635303 DOI: 10.1093/nar/gkl703] [Citation(s) in RCA: 133] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Mitochondrial transcription factor A (TFAM) is an abundant mitochondrial protein of the HMG superfamily, with various putative roles in mitochondrial DNA (mtDNA) metabolism. In this study we have investigated the effects on mtDNA replication of manipulating TFAM expression in cultured human cells. Mammalian mtDNA replication intermediates (RIs) fall into two classes, whose mechanistic relationship is not properly understood. One class is characterized by extensive RNA incorporation on the lagging strand, whereas the other has the structure of products of conventional, strand-coupled replication. TFAM overexpression increased the overall abundance of RIs and shifted them substantially towards those of the conventional, strand-coupled type. The shift was most pronounced in the rDNA region and at various replication pause sites and was accompanied by a drop in the relative amount of replication-termination intermediates, a substantial reduction in mitochondrial transcripts, mtDNA decatenation and progressive copy number depletion. TFAM overexpression could be partially phenocopied by treatment of cells with dideoxycytidine, suggesting that its effects are partially attributable to a decreased rate of fork progression. TFAM knockdown also resulted in mtDNA depletion, but RIs remained mainly of the ribosubstituted type, although termination intermediates were enhanced. We propose that TFAM influences the mode of mtDNA replication via its combined effects on different aspects of mtDNA metabolism.
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Affiliation(s)
- Jaakko L. O. Pohjoismäki
- Institute of Medical Technology and Tampere University HospitalFI-33014 University of Tampere, Finland
| | - Sjoerd Wanrooij
- Institute of Medical Technology and Tampere University HospitalFI-33014 University of Tampere, Finland
| | - Anne K. Hyvärinen
- Institute of Medical Technology and Tampere University HospitalFI-33014 University of Tampere, Finland
| | - Steffi Goffart
- Institute of Medical Technology and Tampere University HospitalFI-33014 University of Tampere, Finland
| | - Ian J. Holt
- MRC-Dunn Human Nutrition Unit, Hill RoadCambridge CB2 2XY, England, UK
| | - Johannes N. Spelbrink
- Institute of Medical Technology and Tampere University HospitalFI-33014 University of Tampere, Finland
| | - Howard T. Jacobs
- Institute of Medical Technology and Tampere University HospitalFI-33014 University of Tampere, Finland
- IBLS Division of Molecular Genetics, University of GlasgowGlasgow G12 8QQ, Scotland, UK
- To whom correspondence should be addressed. Tel: +358 33 55 17 731; Fax: +358 32 15 77 10;
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Rowland SJ, Boocock MR, Stark WM. DNA bending in the Sin recombination synapse: functional replacement of HU by IHF. Mol Microbiol 2006; 59:1730-43. [PMID: 16553879 DOI: 10.1111/j.1365-2958.2006.05064.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The serine recombinase Sin requires a non-specific DNA-bending protein such as Hbsu for activity at its recombination site resH. Hbsu, and Sin subunits bound at site II of resH, together regulate recombination, ensuring selectivity for directly repeated resH sites by specifying assembly of an intertwined synapse. To investigate the role of the DNA-bending protein in defining the architecture of the synapse, we constructed a chimaeric recombination site (resF) which allows Hbsu to be substituted by IHF, binding specifically between site I (the crossover site) and site II. Two Sin dimers and one IHF dimer can bind together to the closely adjoining sites in resF, forming folded complexes. The precise position of the IHF site within the site I-site II spacer determines the conformation of these complexes, and also the reactivity of the resF sites in recombination assays. The data suggest that a sharp bend with a specific geometry is required in the spacer DNA, to bring the Sin dimers at sites I and II together in the correct relative orientation for synapse assembly and regulation, consistent with our model for a highly condensed synapse in which Hbsu/IHF has a purely architectural function.
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Affiliation(s)
- Sally-J Rowland
- University of Glasgow, Institute of Biomedical and Life Sciences, Division of Molecular Genetics, Anderson College, UK.
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Lichota J, Ritt C, Grasser KD. Ectopic expression of the maize chromosomal HMGB1 protein causes defects in root development of tobacco seedlings. Biochem Biophys Res Commun 2004; 318:317-22. [PMID: 15110790 DOI: 10.1016/j.bbrc.2004.03.193] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2004] [Indexed: 10/26/2022]
Abstract
Chromatin-associated high mobility group (HMG) proteins of the HMGB family are versatile architectural factors assisting various DNA-dependent processes such as transcription and recombination. Here, transgenic tobacco lines were generated that ectopically express the maize HMGB1 protein, as detected by immunoblot analyses. The shoot morphology of HMGB1 expressing plants does not differ from that of control plants. By contrast, tobacco seedlings expressing HMGB1 are impaired in the growth of the primary root, relative to control plants. The reduced primary root length is correlated with the accumulation of small cells in the cell division zone (but not in the elongation zone) of the roots of transgenic plants. This "short-root" phenotype is specific for HMGB1, as is not observed with HMGB4 expressing plants, and it is transient in that it is restricted to young seedlings (
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Affiliation(s)
- Jacek Lichota
- Department of Life Sciences, Aalborg University, Sohngaardsholmsvej 49, DK-9000 Aalborg, Denmark
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Lichota J, Grasser KD. Interaction of maize chromatin-associated HMG proteins with mononucleosomes: role of core and linker histones. Biol Chem 2003; 384:1019-27. [PMID: 12956418 DOI: 10.1515/bc.2003.114] [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: 11/15/2022]
Abstract
Two groups of plant chromatin-associated high mobility group (HMG) proteins, namely the HMGA family, typically containing four A/T-hook DNA-binding motifs, and the HMGB family, containing a single HMG-box DNA-binding domain, have been identified. We have examined the interaction of recombinant maize HMGA and five different HMGB proteins with mononucleosomes (containing approx. 165 bp of DNA) purified from micrococcal nuclease-digested maize chromatin. The HMGB proteins interacted with the nucleosomes independent of the presence of the linker histone H1, while the binding of HMGA in the presence of H1 differed from that observed in the absence of H1. HMGA and the HMGB proteins bound H1-containing nucleosome particles with similar affinity. The plant HMG proteins could also bind nucleosomes that were briefly treated with trypsin (removing the N-terminal domains of the core histones), suggesting that the histone N-termini are dispensable for HMG protein binding. In the presence of untreated nucleosomes and trypsinised nucleosomes, HMGB1 could be chemically crosslinked with a core histone, which indicates that the trypsin-resistant part of the histones within the nucleosome is the main interaction partner of HMGB1 rather than the histone N-termini. In conclusion, these results indicate that specific nucleosome binding of the plant HMGB proteins requires simultaneous DNA and histone contacts.
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Affiliation(s)
- Jacek Lichota
- Institute of Life Sciences, Aalborg University, Sohngaardsholmsvej 49, DK-9000 Aalborg, Denmark
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Canosa I, López G, Rojo F, Boocock MR, Alonso JC. Synapsis and strand exchange in the resolution and DNA inversion reactions catalysed by the beta recombinase. Nucleic Acids Res 2003; 31:1038-44. [PMID: 12560501 PMCID: PMC149188 DOI: 10.1093/nar/gkg166] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
In the presence of a sequence-independent chromatin-associated protein, such as Hbsu or HMGB, the beta recombinase catalyses resolution between two directly oriented recombination sites (six sites) and both resolution and DNA inversion between two inversely oriented six sites. Assembly of the synaptic complex requires binding of the beta recombinase to the six sites and the presence of Hbsu. Whether resolution or inversion will take place depends on the relative orientation of the two six sites, the level of DNA supercoiling and the amounts of Hbsu. In this work, the topologies of the products of the resolution and inversion reactions were analysed. The resolution reaction generated mainly singly catenated DNA circles, while DNA inversion gave rise to unknotted circles and small amounts of DNA molecules containing 3- or 5-noded knots. In spite of the distinctive features of the beta system, the topology of synapsis and strand exchange during the resolution reaction is similar to that of Tn3 and gammadelta resolvases. The ability of the beta recombinase to catalyse both inversion and resolution reactions probably reflects different possible architectures of the synaptic complex, which to a large extent depends on Hbsu.
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Affiliation(s)
- Inés Canosa
- Departamento de Biotecnología Microbiana, Centro Nacional de Biotecnología, CSIC, Campus de la Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain
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