Cloning and Characterization of an <i>Arabidopsis thaliana</i> Topoisomerase I Gene

Kieber, Joseph J.; Tissier, Alain; Signer, Ethan R.

doi:10.1104/pp.99.4.1493

Cited by 42 publications

(27 citation statements)

References 31 publications

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“…Here, we show that MGO1 affects cellular decisions and gene expression states during development and genetically acts in cooperation with the transcription factor WUS and chromatin regulators. We find that mgo1 alleles carry lesions in the Arabidopsis type IB topoisomerase gene (TOP) 1a (Kieber et al, 1992;Takahashi et al, 2002), linking DNA topoisomerase function to developmental gene regulation.…”

Section: Discussionmentioning

confidence: 99%

“…Sequencing candidate genes within this interval revealed a single gene (At5g55300) that carries a mutation in all mgo1 alleles analyzed ( Figure 7A). The reading frame encodes the predicted type IB topoisomerase TOP1a (Kieber et al, 1992;Takahashi et al, 2002). The mgo1-4 mutation results in the loss of most of the topoisomerase core domain and the catalytic C-terminal domain, which are highly conserved in eukaryotes, strongly suggesting that mgo1-4 is a null allele ( Figure 7A).…”

Section: Mgo1 Encodes a Topoisomerase Ibmentioning

confidence: 99%

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MGOUN1Encodes anArabidopsisType IB DNA Topoisomerase Required in Stem Cell Regulation and to Maintain Developmentally Regulated Gene Silencing

et al. 2010

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Maintenance of stem cells in the Arabidopsis thaliana shoot meristem is regulated by signals from the underlying cells of the organizing center, provided through the transcription factor WUSCHEL (WUS). Here, we report the isolation of several independent mutants of MGOUN1 (MGO1) as genetic suppressors of ectopic WUS activity and enhancers of stem cell defects in hypomorphic wus alleles. mgo1 mutants have previously been reported to result in a delayed progression of meristem cells into differentiating organ primordia (Laufs et al., 1998). Genetic analyses indicate that MGO1 functions together with WUS in stem cell maintenance at all stages of shoot and floral meristems. Synergistic interactions of mgo1 with several chromatin mutants suggest that MGO1 affects gene expression together with chromatin remodeling pathways. In addition, the expression states of developmentally regulated genes are randomly switched in mgo1 in a mitotically inheritable way, indicating that MGO1 stabilizes epigenetic states against stochastically occurring changes. Positional cloning revealed that MGO1 encodes a putative type IB topoisomerase, which in animals and yeast has been shown to be required for regulation of DNA coiling during transcription and replication. The specific developmental defects in mgo1 mutants link topoisomerase IB function in Arabidopsis to stable propagation of developmentally regulated gene expression.

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Section: Discussionmentioning

confidence: 99%

Section: Mgo1 Encodes a Topoisomerase Ibmentioning

confidence: 99%

MGOUN1Encodes anArabidopsisType IB DNA Topoisomerase Required in Stem Cell Regulation and to Maintain Developmentally Regulated Gene Silencing

et al. 2010

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“…Many of the DEK3-associated proteins are involved in DNA-dependent processes. DNA topoisomerase 1a (Top1a; Kieber et al, 1992) copurified in all three experiments with DEK3. Top1a is a type I DNA topoisomerase involved in DNA replication, recombination, repair, and transcription (Wang, 2002;Leppard and Champoux, 2005), and Arabidopsis Top1a is involved in development (Takahashi et al, 2002;Graf et al, 2010).…”

Section: Dek3 Association With Topoisomerase 1a and Cohesin Componentmentioning

confidence: 99%

A DEK Domain-Containing Protein Modulates Chromatin Structure and Function inArabidopsis

et al. 2014

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Chromatin is a major determinant in the regulation of virtually all DNA-dependent processes. Chromatin architectural proteins interact with nucleosomes to modulate chromatin accessibility and higher-order chromatin structure. The evolutionarily conserved DEK domain-containing protein is implicated in important chromatin-related processes in animals, but little is known about its DNA targets and protein interaction partners. In plants, the role of DEK has remained elusive. In this work, we identified DEK3 as a chromatin-associated protein in Arabidopsis thaliana. DEK3 specifically binds histones H3 and H4. Purification of other proteins associated with nuclear DEK3 also established DNA topoisomerase 1a and proteins of the cohesion complex as in vivo interaction partners. Genome-wide mapping of DEK3 binding sites by chromatin immunoprecipitation followed by deep sequencing revealed enrichment of DEK3 at protein-coding genes throughout the genome. Using DEK3 knockout and overexpressor lines, we show that DEK3 affects nucleosome occupancy and chromatin accessibility and modulates the expression of DEK3 target genes. Furthermore, functional levels of DEK3 are crucial for stress tolerance. Overall, data indicate that DEK3 contributes to modulation of Arabidopsis chromatin structure and function.

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“…Because the mutant phenotype was linked to the T-DNA insertion and segregated as a single recessive mutation (data not shown), we cloned the flanking genome DNA of the insertion in the top1 ␣ -1 allele and found that the insertion occurred in a type-I DNA topoisomerase (topo I) gene that was cloned previously as TOP1 by Kieber et al (1992). Database searches revealed that the Arabidopsis genome has another putative topo I gene located tandemly with the mutated one on chromosome 5 ( Figure 5A).…”

Section: Molecular Cloning Of the Top1 ␣ Locusmentioning

confidence: 99%

Disruption of a DNA Topoisomerase I Gene Affects Morphogenesis in Arabidopsis

et al. 2002

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The genesis of phyllotaxis, which often is associated with the Fibonacci series of numbers, is an old unsolved puzzle in plant morphogenesis. Here, we show that disruption of an Arabidopsis topoisomerase (topo) I gene named TOP1 ␣ affects phyllotaxis and plant architecture. The divergence angles and internode lengths between two successive flowers were more random in the top1 ␣ mutant than in the wild type. The top1 ␣ plants sporadically produced multiple flowers from one node, and the number of floral organ primordia often was different. The mutation also caused the twisting of inflorescences and individual flowers and the serration of leaf margins. These morphological abnormalities indicate that TOP1 ␣ may play a critical role in the maintenance of a regular pattern of organ initiation. The top1 ␣ mutant transformed with the RNA interference construct for TOP1 ␤ , another topo I gene arrayed tandemly with TOP1 ␣ , was found to be lethal at young seedling stages, suggesting that topo I activity is essential in plants.

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Cloning and Characterization of an Arabidopsis thaliana Topoisomerase I Gene

Cited by 42 publications

References 31 publications

MGOUN1Encodes anArabidopsisType IB DNA Topoisomerase Required in Stem Cell Regulation and to Maintain Developmentally Regulated Gene Silencing

MGOUN1Encodes anArabidopsisType IB DNA Topoisomerase Required in Stem Cell Regulation and to Maintain Developmentally Regulated Gene Silencing

A DEK Domain-Containing Protein Modulates Chromatin Structure and Function inArabidopsis

Disruption of a DNA Topoisomerase I Gene Affects Morphogenesis in Arabidopsis

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