RESUMO
In eukaryotes, DNA wraps around histones to form nucleosomes, which are compacted into chromatin. DNA-templated processes, including transcription, require chromatin disassembly and reassembly mediated by histone chaperones. Additionally, distinct histone variants can replace core histones to regulate chromatin structure and function. Although replacement of H2A with the evolutionarily conserved H2A.Z via the SWR1 histone chaperone complex has been extensively studied, in plants little is known about how a reduction of H2A.Z levels can be achieved. Here, we show that NRP proteins cause a decrease of H2A.Z-containing nucleosomes in Arabidopsis under standard growing conditions. nrp1-1 nrp2-2 double mutants show an over-accumulation of H2A.Z genome-wide, especially at heterochromatic regions normally H2A.Z-depleted in wild-type plants. Our work suggests that NRP proteins regulate gene expression by counteracting SWR1, thereby preventing excessive accumulation of H2A.Z.
Assuntos
Proteínas de Arabidopsis/genética , Arabidopsis/genética , Montagem e Desmontagem da Cromatina/genética , Cromatina/genética , Histonas/genética , Chaperonas Moleculares/genética , Adenosina Trifosfatases/genética , Adenosina Trifosfatases/metabolismo , Arabidopsis/metabolismo , Proteínas de Arabidopsis/metabolismo , Cromatina/metabolismo , Regulação da Expressão Gênica de Plantas , Genoma de Planta/genética , Histonas/metabolismo , Chaperonas Moleculares/metabolismo , Mutação , Nucleossomos/genética , Nucleossomos/metabolismo , Sequenciamento Completo do Genoma/métodosRESUMO
The initiation of flowering in plants is controlled by environmental and endogenous signals. Molecular analysis of this process in Arabidopsis thaliana indicates that environmental control is exerted through the photoperiod and vernalization pathways, whereas endogenous signals regulate the autonomous and gibberellin pathways. The vernalization and autonomous pathways converge on the negative regulation of FLC, a gene encoding a MADS-box protein that inhibits flowering. We cloned FVE, a component of the autonomous pathway that encodes AtMSI4, a putative retinoblastoma-associated protein. FVE interacted with retinoblastoma protein in immunoprecipitation assays, and FLC chromatin was enriched in acetylated histones in fve mutants. We conclude that FVE participates in a protein complex repressing FLC transcription through a histone deacetylation mechanism. Our data provide genetic evidence of a new developmental function of these conserved proteins and identify a new genetic mechanism in the regulation of flowering.