Characterization of the functional connection between the BROMODOMAIN and EXTRATERMINAL DOMAIN PROTEIN 9 (BET9) and the circadian clock in Arabidopsis thaliana
[eng] The circadian clock is an endogenously generated timekeeping mechanism that generates 24-hour rhythms in multiple biological processes. The rhythmic oscillations provide an adaptive advantage, allowing organisms to anticipate and adjust to the environmental changes that occur during the day an...
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| Tipo de recurso: | tesis doctoral |
| Estado: | Versión publicada |
| Fecha de publicación: | 2021 |
| País: | España |
| Institución: | Universidad de Barcelona |
| Repositorio: | Dipòsit Digital de la UB |
| OAI Identifier: | oai:diposit.ub.edu:2445/184273 |
| Acceso en línea: | https://hdl.handle.net/2445/184273 http://hdl.handle.net/10803/673868 |
| Access Level: | acceso abierto |
| Palabra clave: | Ritmes circadiaris Cromatina Arabidopsis thaliana Circadian rhythms Chromatin |
| Sumario: | [eng] The circadian clock is an endogenously generated timekeeping mechanism that generates 24-hour rhythms in multiple biological processes. The rhythmic oscillations provide an adaptive advantage, allowing organisms to anticipate and adjust to the environmental changes that occur during the day and night cycle. The generation of the rhythms rely on the oscillations in gene expression and protein function at the core of the oscillator. Over the last years, changes in chromatin marks have been identified as an important mechanism contributing to the rhythmic oscillations. However, we are still far from the identification of the chromatin-related components that are responsible for the rhythmic regulation of these chromatin changes. In this Doctoral Thesis, we have characterized the function of the BROMODOMAIN AND EXTRA- TERMINAL DOMAIN 9 (BET9) protein within the Arabidopsis thaliana circadian clock. We have identified the rhythmic oscillation of BET9 expression, which is controlled by the binding of the clock activator known as REVEILLE 8 (RVE8) to the BET9 promoter. Characterization of bet9 mutant plants and lines over- expressing BET9 (BET9-ox) showed that BET9 functions as an activator of clock gene expression. Chromatin immunoprecipitation assays (ChIP) also showed that BET9 directly binds to the promoters of essential clock genes such as TIMING OF CAB2 EXPRESSION 1 (TOC1) and PSEUDO RESPONSE REGULATOR 5 (PRR5). Increased binding of BET9 to these promoters in BET9-ox plants correlated with increased HISTONE 3 acetylation at the TOC1 promoter, and conversely, with hypoacetylation in the bet9 mutant. Genetic interaction studies showed that BET9 requires a functional RVE8, as the BET9-ox gene expression phenotypes and BET9 binding to the gene target promoters were abolished in the rve8 mutant background. Our studies have thus uncovered a chromatin-related protein that together with RVE8 contributes to the activation of clock gene expression. |
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