title: A JUMONJI Protein with E3 Ligase and Histone H3 Binding Activities Affects Transposon Silencing in Arabidopsis.
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.
authors.affiliation: Institute for Biochemistry and Biology, University of Potsdam, 14476 Potsdam, Germany (T.K., K.B., T.F., C.K., I.B.); andMax-Planck-Institute for Molecular Plant Physiology, 14476 Potsdam, Germany (M.G., A.G.).
authors.forename: Tina
authors.initials: T
authors.lastname: Kabelitz
authors.affiliation: Institute for Biochemistry and Biology, University of Potsdam, 14476 Potsdam, Germany (T.K., K.B., T.F., C.K., I.B.); andMax-Planck-Institute for Molecular Plant Physiology, 14476 Potsdam, Germany (M.G., A.G.).
authors.forename: Krzysztof
authors.initials: K
authors.lastname: Brzezinka
authors.affiliation: Institute for Biochemistry and Biology, University of Potsdam, 14476 Potsdam, Germany (T.K., K.B., T.F., C.K., I.B.); andMax-Planck-Institute for Molecular Plant Physiology, 14476 Potsdam, Germany (M.G., A.G.).
authors.forename: Thomas
authors.identifier: 0000-0003-2038-3670
authors.initials: T
authors.lastname: Friedrich
authors.affiliation: Institute for Biochemistry and Biology, University of Potsdam, 14476 Potsdam, Germany (T.K., K.B., T.F., C.K., I.B.); andMax-Planck-Institute for Molecular Plant Physiology, 14476 Potsdam, Germany (M.G., A.G.).
authors.forename: Michał
authors.identifier: 0000-0002-1289-6858
authors.initials: M
authors.lastname: Górka
authors.affiliation: Institute for Biochemistry and Biology, University of Potsdam, 14476 Potsdam, Germany (T.K., K.B., T.F., C.K., I.B.); andMax-Planck-Institute for Molecular Plant Physiology, 14476 Potsdam, Germany (M.G., A.G.).
authors.forename: Alexander
authors.initials: A
authors.lastname: Graf
authors.affiliation: Institute for Biochemistry and Biology, University of Potsdam, 14476 Potsdam, Germany (T.K., K.B., T.F., C.K., I.B.); andMax-Planck-Institute for Molecular Plant Physiology, 14476 Potsdam, Germany (M.G., A.G.).
authors.forename: Christian
authors.identifier: 0000-0002-1450-1864
authors.initials: C
authors.lastname: Kappel
authors.affiliation: Institute for Biochemistry and Biology, University of Potsdam, 14476 Potsdam, Germany (T.K., K.B., T.F., C.K., I.B.); andMax-Planck-Institute for Molecular Plant Physiology, 14476 Potsdam, Germany (M.G., A.G.) isabel.baeurle@uni-potsdam.de.
authors.forename: Isabel
authors.identifier: 0000-0001-5633-8068
authors.initials: I
authors.lastname: Bäurle
mesh_terms: D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D001665:Binding Sites; D004251:DNA Transposable Elements; D044127:Epigenesis, Genetic; D018506:Gene Expression Regulation, Plant; D020868:Gene Silencing; D006657:Histones / Q000378:metabolism*; D007501:Iron / Q000378:metabolism; D056484:Jumonji Domain-Containing Histone Demethylases / Q000235:genetics / Q000378:metabolism*; D008239:Lysine / Q000378:metabolism; D010802:Phylogeny; D030821:Plants, Genetically Modified; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism; D054875:Ubiquitination
chemical_list: D029681:Arabidopsis Proteins; D004251:DNA Transposable Elements; D006657:Histones; D007501:Iron; C000608068:JMJ24 protein, Arabidopsis; D056484:Jumonji Domain-Containing Histone Demethylases; D044767:Ubiquitin-Protein Ligases; D008239:Lysine