RESUMEN
Deposition of H2A.Z in chromatin is known to be mediated by a conserved SWR1 chromatin-remodeling complex in eukaryotes. However, little is known about whether and how the SWR1 complex cooperates with other chromatin regulators. Using immunoprecipitation followed by mass spectrometry, we found all known components of the Arabidopsis thaliana SWR1 complex and additionally identified the following three classes of previously uncharacterized plant-specific SWR1 components: MBD9, a methyl-CpG-binding domain-containing protein; CHR11 and CHR17 (CHR11/17), ISWI chromatin remodelers responsible for nucleosome sliding; and TRA1a and TRA1b, accessory subunits of the conserved NuA4 histone acetyltransferase complex. MBD9 directly interacts with CHR11/17 and the SWR1 catalytic subunit PIE1, and is responsible for the association of CHR11/17 with the SWR1 complex. MBD9, TRA1a, and TRA1b function as canonical components of the SWR1 complex to mediate H2A.Z deposition. CHR11/17 are not only responsible for nucleosome sliding but also involved in H2A.Z deposition. These results indicate that the association of the SWR1 complex with CHR11/17 may facilitate the coupling of H2A.Z deposition with nucleosome sliding, thereby co-regulating gene expression, development, and flowering time.
Asunto(s)
Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Proteínas de Unión al ADN/metabolismo , Histonas/metabolismo , Adenosina Trifosfatasas/metabolismo , Cromatina/metabolismo , Ensamble y Desensamble de Cromatina , Histona Acetiltransferasas/metabolismo , Nucleosomas/metabolismo , Mapas de Interacción de Proteínas , Factores de Transcripción/metabolismoRESUMEN
The SU(VAR)3-9 homolog SUVH9 and the double-stranded RNA-binding protein IDN2 were thought to be components of an RNA-directed DNA methylation (RdDM) pathway in Arabidopsis. We previously found that SUVH9 interacts with MORC6 but how the interaction contributes to transcriptional silencing remains elusive. Here, our genetic analysis indicates that SUVH2 and SUVH9 can either act in the same pathway as MORC6 or act synergistically with MORC6 to mediate transcriptional silencing. Moreover, we demonstrate that IDN2 interacts with MORC6 and mediates the silencing of a subset of MORC6 target loci. Like SUVH2, SUVH9, and IDN2, other RdDM components including Pol IV, Pol V, RDR2, and DRM2 are also required for transcriptional silencing at a subset of MORC6 target loci. MORC6 was previously shown to mediate transcriptional silencing through heterochromatin condensation. We demonstrate that the SWI/SNF chromatin-remodeling complex components SWI3B, SWI3C, and SWI3D interact with MORC6 as well as with SUVH9 and then mediate transcriptional silencing. These results suggest that the RdDM components are involved not only in DNA methylation but also in MORC6-mediated heterochromatin condensation. This study illustrates how DNA methylation is linked to heterochromatin condensation and thereby enhances transcriptional silencing at methylated genomic regions.
Asunto(s)
Adenosina Trifosfatasas/genética , Proteínas de Arabidopsis/genética , Heterocromatina/genética , Metiltransferasas/genética , Transcripción Genética , Adenosina Trifosfatasas/metabolismo , Proteínas de Arabidopsis/metabolismo , Ensamble y Desensamble de Cromatina/genética , Metilación de ADN/genética , Regulación de la Expresión Génica de las Plantas , Silenciador del Gen , N-Metiltransferasa de Histona-Lisina/genética , N-Metiltransferasa de Histona-Lisina/metabolismo , Metiltransferasas/metabolismo , ARN Bicatenario/genética , Proteínas de Unión al ARN/genética , Proteínas de Unión al ARN/metabolismoRESUMEN
RNA-directed DNA methylation (RdDM) is required for transcriptional silencing of transposons and other DNA repeats in Arabidopsis thaliana. Although previous research has demonstrated that the SET domain-containing SU(VAR)3-9 homologs SUVH2 and SUVH9 are involved in the RdDM pathway, the underlying mechanism remains unknown. Our results indicated that SUVH2 and/or SUVH9 not only interact with the chromatin-remodeling complex termed DDR (DMS3, DRD1, and RDM1) but also with the newly characterized complex composed of two conserved Microrchidia (MORC) family proteins, MORC1 and MORC6. The effect of suvh2suvh9 on Pol IV-dependent siRNA accumulation and DNA methylation is comparable to that of the Pol V mutant nrpe1 and the DDR complex mutant dms3, suggesting that SUVH2 and SUVH9 are functionally associated with RdDM. Our CHIP assay demonstrated that SUVH2 and SUVH9 are required for the occupancy of Pol V at RdDM loci and facilitate the production of Pol V-dependent noncoding RNAs. Moreover, SUVH2 and SUVH9 are also involved in the occupancy of DMS3 at RdDM loci. The putative catalytic active site in the SET domain of SUVH2 is dispensable for the function of SUVH2 in RdDM and H3K9 dimethylation. We propose that SUVH2 and SUVH9 bind to methylated DNA and facilitate the recruitment of Pol V to RdDM loci by associating with the DDR complex and the MORC complex.
Asunto(s)
Proteínas de Arabidopsis/genética , Ensamble y Desensamble de Cromatina/genética , ARN Polimerasas Dirigidas por ADN/genética , N-Metiltransferasa de Histona-Lisina/genética , Adenosina Trifosfatasas/genética , Adenosina Trifosfatasas/metabolismo , Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Proteínas Cromosómicas no Histona/genética , Proteínas Cromosómicas no Histona/metabolismo , Metilación de ADN/genética , Proteínas de Unión al ADN/genética , Proteínas de Unión al ADN/metabolismo , Estructura Terciaria de Proteína/genética , ARN/genética , ARN Interferente Pequeño/genética , ARN no Traducido/genéticaRESUMEN
OBJECTIVE: To study the general law of typing of bronchiectasis according to syndrome differentiation. METHODS: We collected the symptoms, conditions of tongue and pulse in patients of bronchiectasis, using frequencies procedure, discriminant analysis and K-means cluster analysis in SPSS statistical software as research medium. RESULTS: Five hundred and sixty three patients with bronchiectasis were studied. It suggested that accumulation of phlegm-heat in the lungs (45.65%), liver fire attacking the lungs (24.51%), asthenia of pulmonosplenic qi (22.38%), asthenia of both qi and yin (7.46%) were the main types. CONCLUSION: Clinical epidemiology provided scientific basis for further studying of the typing of bronchiectasis according to syndrome differentiation. Building up differentiation of syndromes through differentiation and analysis of main symptoms can be used in clinical diagnosis.