TY - JOUR A1 - Kabelitz, Tina A1 - Brzezinka, Krzysztof A1 - Friedrich, Thomas A1 - Gorka, Michal A1 - Graf, Alexander A1 - Kappel, Christian A1 - Bäurle, Isabel T1 - A JUMONJI Protein with E3 Ligase and Histone H3 Binding Activities Affects Transposon Silencing in Arabidopsis JF - Plant physiology : an international journal devoted to physiology, biochemistry, cellular and molecular biology, biophysics and environmental biology of plants N2 - 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. Y1 - 2016 U6 - https://doi.org/10.1104/pp.15.01688 SN - 0032-0889 SN - 1532-2548 VL - 171 SP - 344 EP - 358 PB - American Society of Plant Physiologists CY - Rockville ER - TY - JOUR A1 - Friedrich, Thomas A1 - Faivre, Lea A1 - Bäurle-Lenhard, Isabel A1 - Schubert, Daniel T1 - Chromatin-based mechanisms of temperature memory in plants JF - Plant, cell & environment : cell physiology, whole-plant physiology, community physiology N2 - For successful growth and development, plants constantly have to gauge their environment. Plants are capable to monitor their current environmental conditions, and they are also able to integrate environmental conditions over time and store the information induced by the cues. In a developmental context, such an environmental memory is used to align developmental transitions with favourable environmental conditions. One temperature-related example of this is the transition to flowering after experiencing winter conditions, that is, vernalization. In the context of adaptation to stress, such an environmental memory is used to improve stress adaptation even when the stress cues are intermittent. A somatic stress memory has now been described for various stresses, including extreme temperatures, drought, and pathogen infection. At the molecular level, such a memory of the environment is often mediated by epigenetic and chromatin modifications. Histone modifications in particular play an important role. In this review, we will discuss and compare different types of temperature memory and the histone modifications, as well as the reader, writer, and eraser proteins involved. KW - chromatin KW - cold KW - epigenetics KW - heat KW - memory KW - nucleosome remodelling KW - polycomb KW - priming KW - trithorax Y1 - 2018 U6 - https://doi.org/10.1111/pce.13373 SN - 0140-7791 SN - 1365-3040 VL - 42 IS - 3 SP - 762 EP - 770 PB - Wiley CY - Hoboken ER - TY - JOUR A1 - Castellanos, Reynel Urrea A1 - Friedrich, Thomas A1 - Petrovic, Nevena A1 - Altmann, Simone A1 - Brzezinka, Krzysztof A1 - Gorka, Michal A1 - Graf, Alexander A1 - Bäurle, Isabel T1 - FORGETTER2 protein phosphatase and phospholipase D modulate heat stress memory in Arabidopsis JF - The plant journal N2 - Plants can mitigate environmental stress conditions through acclimation. In the case of fluctuating stress conditions such as high temperatures, maintaining a stress memory enables a more efficient response upon recurring stress. In a genetic screen forArabidopsis thalianamutants impaired in the memory of heat stress (HS) we have isolated theFORGETTER2(FGT2) gene, which encodes a type 2C protein phosphatase (PP2C) of the D-clade.Fgt2mutants acquire thermotolerance normally; however, they are defective in the memory of HS. FGT2 interacts with phospholipase D alpha 2 (PLD alpha 2), which is involved in the metabolism of membrane phospholipids and is also required for HS memory. In summary, we have uncovered a previously unknown component of HS memory and identified the FGT2 protein phosphatase and PLD alpha 2 as crucial players, suggesting that phosphatidic acid-dependent signaling or membrane composition dynamics underlie HS memory. KW - priming KW - protein phosphatase KW - stress memory KW - heat stress KW - Arabidopsis KW - thaliana Y1 - 2020 U6 - https://doi.org/10.1111/tpj.14927 SN - 0960-7412 SN - 1365-313X VL - 104 IS - 1 SP - 7 EP - 17 PB - Wiley CY - Hoboken ER - TY - JOUR A1 - Friedrich, Thomas A1 - Oberkofler, Vicky A1 - Trindade, Inês A1 - Altmann, Simone A1 - Brzezinka, Krzysztof A1 - Lämke, Jörn S. A1 - Gorka, Michal A1 - Kappel, Christian A1 - Sokolowska, Ewelina A1 - Skirycz, Aleksandra A1 - Graf, Alexander A1 - Bäurle, Isabel T1 - Heteromeric HSFA2/HSFA3 complexes drive transcriptional memory after heat stress in Arabidopsis JF - Nature Communications N2 - Adaptive plasticity in stress responses is a key element of plant survival strategies. For instance, moderate heat stress (HS) primes a plant to acquire thermotolerance, which allows subsequent survival of more severe HS conditions. Acquired thermotolerance is actively maintained over several days (HS memory) and involves the sustained induction of memory-related genes. Here we show that FORGETTER3/ HEAT SHOCK TRANSCRIPTION FACTOR A3 (FGT3/HSFA3) is specifically required for physiological HS memory and maintaining high memory-gene expression during the days following a HS exposure. HSFA3 mediates HS memory by direct transcriptional activation of memory-related genes after return to normal growth temperatures. HSFA3 binds HSFA2, and in vivo both proteins form heteromeric complexes with additional HSFs. Our results indicate that only complexes containing both HSFA2 and HSFA3 efficiently promote transcriptional memory by positively influencing histone H3 lysine 4 (H3K4) hyper-methylation. In summary, our work defines the major HSF complex controlling transcriptional memory and elucidates the in vivo dynamics of HSF complexes during somatic stress memory. Moderate heat stress primes plants to acquire tolerance to subsequent, more severe heat stress. Here the authors show that the HSFA3 transcription factor forms a heteromeric complex with HSFA2 to sustain activated transcription of genes required for acquired thermotolerance by promoting H3K4 hyper-methylation. Y1 - 2021 U6 - https://doi.org/10.1038/s41467-021-23786-6 SN - 2041-1723 VL - 12 IS - 1 PB - Nature Publishing Group UK CY - [London] ER -