@article{BrzezinkaAltmannCzesnicketal.2016, author = {Brzezinka, Krzysztof and Altmann, Simone and Czesnick, Hj{\"o}rdis and Nicolas, Philippe and Gorka, Michal and Benke, Eileen and Kabelitz, Tina and J{\"a}hne, Felix and Graf, Alexander and Kappel, Christian and B{\"a}urle, Isabel}, title = {Arabidopsis FORGETTER1 mediates stress-induced chromatin memory through nucleosome remodeling}, series = {eLife}, volume = {5}, journal = {eLife}, publisher = {eLife Sciences Publications}, address = {Cambridge}, issn = {2050-084X}, doi = {10.7554/eLife.17061}, pages = {23}, year = {2016}, abstract = {Plants as sessile organisms can adapt to environmental stress to mitigate its adverse effects. As part of such adaptation they maintain an active memory of heat stress for several days that promotes a more efficient response to recurring stress. We show that this heat stress memory requires the activity of the FORGETTER1 (FGT1) locus, with fgt1 mutants displaying reduced maintenance of heat-induced gene expression. FGT1 encodes the Arabidopsis thaliana orthologue of Strawberry notch (Sno), and the protein globally associates with the promoter regions of actively expressed genes in a heat-dependent fashion. FGT1 interacts with chromatin remodelers of the SWI/ SNF and ISWI families, which also display reduced heat stress memory. Genomic targets of the BRM remodeler overlap significantly with FGT1 targets. Accordingly, nucleosome dynamics at loci with altered maintenance of heat-induced expression are affected in fgt1. Together, our results suggest that by modulating nucleosome occupancy, FGT1 mediates stress-induced chromatin memory.}, language = {en} } @article{LaemkeBrzezinkaAltmannetal.2016, author = {L{\"a}mke, J{\"o}rn and Brzezinka, Krzysztof and Altmann, Simone and B{\"a}urle, Isabel}, title = {A hit-and-run heat shock factor governs sustained histone methylation and transcriptional stress memory}, series = {The EMBO journal}, volume = {35}, journal = {The EMBO journal}, publisher = {Wiley-Blackwell}, address = {Hoboken}, issn = {0261-4189}, doi = {10.15252/embj.201592593}, pages = {162 -- 175}, year = {2016}, abstract = {In nature, plants often encounter chronic or recurring stressful conditions. Recent results indicate that plants can remember a past exposure to stress to be better prepared for a future stress incident. However, the molecular basis of this is poorly understood. Here, we report the involvement of chromatin modifications in the maintenance of acquired thermotolerance (heat stress [HS] memory). HS memory is associated with the accumulation of histone H3 lysine 4 di- and trimethylation at memory-related loci. This accumulation outlasts their transcriptional activity and marks them as recently transcriptionally active. High accumulation of H3K4 methylation is associated with hyper-induction of gene expression upon a recurring HS. This transcriptional memory and the sustained accumulation of H3K4 methylation depend on HSFA2, a transcription factor that is required for HS memory, but not initial heat responses. Interestingly, HSFA2 associates with memory-related loci transiently during the early stages following HS. In summary, we show that transcriptional memory after HS is associated with sustained H3K4 hyper-methylation and depends on a hit-and-run transcription factor, thus providing a molecular framework for HS memory.}, language = {en} } @article{KabelitzBrzezinkaFriedrichetal.2016, author = {Kabelitz, Tina and Brzezinka, Krzysztof and Friedrich, Thomas and Gorka, Michal and Graf, Alexander and Kappel, Christian and B{\"a}urle, Isabel}, title = {A JUMONJI Protein with E3 Ligase and Histone H3 Binding Activities Affects Transposon Silencing in Arabidopsis}, series = {Plant physiology : an international journal devoted to physiology, biochemistry, cellular and molecular biology, biophysics and environmental biology of plants}, volume = {171}, journal = {Plant physiology : an international journal devoted to physiology, biochemistry, cellular and molecular biology, biophysics and environmental biology of plants}, publisher = {American Society of Plant Physiologists}, address = {Rockville}, issn = {0032-0889}, doi = {10.1104/pp.15.01688}, pages = {344 -- 358}, year = {2016}, abstract = {Transposable elements (TEs) make up a large proportion of eukaryotic genomes. As their mobilization creates genetic variation that threatens genome integrity, TEs are epigenetically silenced through several pathways, and this may spread to neighboring sequences. JUMONJI (JMJ) proteins can function as antisilencing factors and prevent silencing of genes next to TEs. Whether TE silencing is counterbalanced by the activity of antisilencing factors is still unclear. Here, we characterize JMJ24 as a regulator of TE silencing. We show that loss of JMJ24 results in increased silencing of the DNA transposon AtMu1c, while overexpression of JMJ24 reduces silencing. JMJ24 has a JumonjiC (JmjC) domain and two RING domains. JMJ24 autoubiquitinates in vitro, demonstrating E3 ligase activity of the RING domain(s). JMJ24-JmjC binds the N-terminal tail of histone H3, and full-length JMJ24 binds histone H3 in vivo. JMJ24 activity is anticorrelated with histone H3 Lys 9 dimethylation (H3K9me2) levels at AtMu1c. Double mutant analyses with epigenetic silencing mutants suggest that JMJ24 antagonizes histone H3K9me2 and requires H3K9 methyltransferases for its activity on AtMu1c. Genome-wide transcriptome analysis indicates that JMJ24 affects silencing at additional TEs. Our results suggest that the JmjC domain of JMJ24 has lost demethylase activity but has been retained as a binding domain for histone H3. This is in line with phylogenetic analyses indicating that JMJ24 (with the mutated JmjC domain) is widely conserved in angiosperms. Taken together, this study assigns a role in TE silencing to a conserved JmjC-domain protein with E3 ligase activity, but no demethylase activity.}, language = {en} } @article{HilkerSchwachtjeBaieretal.2016, author = {Hilker, Monika and Schwachtje, Jens and Baier, Margarete and Balazadeh, Salma and B{\"a}urle, Isabel and Geiselhardt, Sven and Hincha, Dirk K. and Kunze, Reinhard and Mueller-Roeber, Bernd and Rillig, Matthias G. and Rolff, Jens and Schm{\"u}lling, Thomas and Steppuhn, Anke and van Dongen, Joost and Whitcomb, Sarah J. and Wurst, Susanne and Zuther, Ellen and Kopka, Joachim}, title = {Priming and memory of stress responses in organisms lacking a nervous system}, series = {Biological reviews}, volume = {91}, journal = {Biological reviews}, publisher = {Wiley-Blackwell}, address = {Hoboken}, issn = {1464-7931}, doi = {10.1111/brv.12215}, pages = {1118 -- 1133}, year = {2016}, language = {en} } @article{CuongNguyenHuuKappelKelleretal.2016, author = {Cuong Nguyen Huu, and Kappel, Christian and Keller, Barbara and Sicard, Adrien and Takebayashi, Yumiko and Breuninger, Holger and Nowak, Michael D. and B{\"a}urle, Isabel and Himmelbach, Axel and Burkart, Michael and Ebbing-Lohaus, Thomas and Sakakibara, Hitoshi and Altschmied, Lothar and Conti, Elena and Lenhard, Michael}, title = {Presence versus absence of CYP734A50 underlies the style-length dimorphism in primroses}, series = {eLife}, volume = {5}, journal = {eLife}, publisher = {eLife Sciences Publications}, address = {Cambridge}, issn = {2050-084X}, doi = {10.7554/eLife.17956}, pages = {15}, year = {2016}, abstract = {Heterostyly is a wide-spread floral adaptation to promote outbreeding, yet its genetic basis and evolutionary origin remain poorly understood. In Primula (primroses), heterostyly is controlled by the S-locus supergene that determines the reciprocal arrangement of reproductive organs and incompatibility between the two morphs. However, the identities of the component genes remain unknown. Here, we identify the Primula CYP734A50 gene, encoding a putative brassinosteroid-degrading enzyme, as the G locus that determines the style-length dimorphism. CYP734A50 is only present on the short-styled S-morph haplotype, it is specifically expressed in S-morph styles, and its loss or inactivation leads to long styles. The gene arose by a duplication specific to the Primulaceae lineage and shows an accelerated rate of molecular evolution. Thus, our results provide a mechanistic explanation for the Primula style-length dimorphism and begin to shed light on the evolution of the S-locus as a prime model for a complex plant supergene.}, language = {en} }