Arabidopsis MSI1 has fundamental functions in plant development. MSI1 is a subunit of Polycomb group protein complexes and Chromatin assembly factor 1, and it interacts with the Retinoblastoma-related protein 1. Alter...Arabidopsis MSI1 has fundamental functions in plant development. MSI1 is a subunit of Polycomb group protein complexes and Chromatin assembly factor 1, and it interacts with the Retinoblastoma-related protein 1. Altered levels of MSI1 result in pleiotropic phenotypes, reflecting the complexity of MSI1 protein functions. In order to uncover additional functions of MSI1, we performed transcriptional profiling of wild-type and plants with highly reduced MSI1 levels （msil-cs）. Surprisingly, the known functions of MSI1 could only account for a minor part of the transcriptional changes in msil-cs plants. One of the most striking unexpected observations was the up-regulation of a subset of ABA-responsive genes eliciting the response to drought and salt stress. We report that MSI1 can bind to the chromatin of the drought-inducible downstream target RD20 and suggest a new role for MSI1 in the negative regulation of the Arabidopsis drought-stress response.展开更多
In the half century since the discovery of the double-helix structure of DNA, it has become increasingly clear that DNA functionality is based on much more than its sequence in a double-helical structure. Further adva...In the half century since the discovery of the double-helix structure of DNA, it has become increasingly clear that DNA functionality is based on much more than its sequence in a double-helical structure. Further advances have highlighted the importance of additional aspects of DNA structure： its packaging in the higher order chromatin structure, positioning of nucleosomes along the DNA, and the occurrence of non-helical DNA structures. Of these, the latter has been problematic to prove empirically. Here, we describe a method that uses non-denaturing bisulfite sequencing on isolated Arabidopsis thaliana nuclei to determine the location of cytosines positioned outside the double helix as a result of non-B-form DNA structures. We couple this with computational methods and S1 nuclease digest to reliably identify stable, non-B-form, cruciform structures. This enables us to identify a palindrome in the promoter of FLOWERING LOCUS T that forms a stable non-B-form structure. The stronger conservation of the ability to form a nonhelical secondary structure than of the sequence suggests that this structure is biologically relevant.展开更多
Vernalization, the acquisition of competence to flower after extended cold treatment, has puzzled researchers throughout the last century. Great progress in understanding the molecular mechanisms of vernalization in A...Vernalization, the acquisition of competence to flower after extended cold treatment, has puzzled researchers throughout the last century. Great progress in understanding the molecular mechanisms of vernalization in Arabidopsis has been made in the course of the last 20 years, placing the flowering repressor- encoding gene FLOWERING LOCUS C （FLC） in the limelight （Bouch6 et al., 2017）. In vernalization-dependent accessions, FRIGIDA （FRI） ensures strong expression of FLC that delays flowering, and extended exposure to low temperatures such as during winter leads to stable repression of FLC, which in turn clears the way for induction of flowering.展开更多
文摘Arabidopsis MSI1 has fundamental functions in plant development. MSI1 is a subunit of Polycomb group protein complexes and Chromatin assembly factor 1, and it interacts with the Retinoblastoma-related protein 1. Altered levels of MSI1 result in pleiotropic phenotypes, reflecting the complexity of MSI1 protein functions. In order to uncover additional functions of MSI1, we performed transcriptional profiling of wild-type and plants with highly reduced MSI1 levels （msil-cs）. Surprisingly, the known functions of MSI1 could only account for a minor part of the transcriptional changes in msil-cs plants. One of the most striking unexpected observations was the up-regulation of a subset of ABA-responsive genes eliciting the response to drought and salt stress. We report that MSI1 can bind to the chromatin of the drought-inducible downstream target RD20 and suggest a new role for MSI1 in the negative regulation of the Arabidopsis drought-stress response.
文摘In the half century since the discovery of the double-helix structure of DNA, it has become increasingly clear that DNA functionality is based on much more than its sequence in a double-helical structure. Further advances have highlighted the importance of additional aspects of DNA structure： its packaging in the higher order chromatin structure, positioning of nucleosomes along the DNA, and the occurrence of non-helical DNA structures. Of these, the latter has been problematic to prove empirically. Here, we describe a method that uses non-denaturing bisulfite sequencing on isolated Arabidopsis thaliana nuclei to determine the location of cytosines positioned outside the double helix as a result of non-B-form DNA structures. We couple this with computational methods and S1 nuclease digest to reliably identify stable, non-B-form, cruciform structures. This enables us to identify a palindrome in the promoter of FLOWERING LOCUS T that forms a stable non-B-form structure. The stronger conservation of the ability to form a nonhelical secondary structure than of the sequence suggests that this structure is biologically relevant.
文摘Vernalization, the acquisition of competence to flower after extended cold treatment, has puzzled researchers throughout the last century. Great progress in understanding the molecular mechanisms of vernalization in Arabidopsis has been made in the course of the last 20 years, placing the flowering repressor- encoding gene FLOWERING LOCUS C （FLC） in the limelight （Bouch6 et al., 2017）. In vernalization-dependent accessions, FRIGIDA （FRI） ensures strong expression of FLC that delays flowering, and extended exposure to low temperatures such as during winter leads to stable repression of FLC, which in turn clears the way for induction of flowering.
