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Descripción
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| The substitution of histone H2A by the histone variant H2A.Z is catalyzed by the chromatin remodelling complex SWR1, which has been proposed to play a key role in achieving high levels of FLOWERING LOCUS C (FLC) expression during the vegetative phase of Arabidopsis. We are characterizing the Arabidopsis homologues of the SWC6, SWC4 and YAF9 components of the yeast SWR1 complex. The subunits SWC4 and YAF9 are shared with the histone acetyltransferase complex NuA4. Both SWR1-C and NuA4-C have an intimate relationship in yeast, regulating multiple biological processes such as gene expression, heterochromatin boundary maintenance, and DNA repair. We have identified putative orthologues for the YAF9 gene, YAF9A and YAF9B, the only two YEATS domain-containing proteins present in the Arabidopsis genome, as well as orthologues for the SWC6 and SWC4 genes. In this work, we have determined that swc6 and double mutant yaf9a yaf9b show early flowering and display pleiotropic defects in both vegetative and reproductive development. Indeed, SWC6 is implicated in flowering inhibition through both FLC and FLC-like genes dependent pathways. On the other hand, microarray data involving the yaf9a yaf9b double mutant corroborates the participation of these genes in the control of several developmental processes. Besides, a knockout allele for AtSWC4 results to be lethal, indicating the essentiality of this protein as its yeast orthologue. For this reason, we have generated RNAi lines to knockdown the expression of the AtSWC4 gene and we have demonstrated that they display pleiotropic phenotypic alterations in vegetative and reproductive traits. Additionally, we have demonstrated that SWC6, SWC4 and YAF9A establish physical interactions each other, in vitro. Otherwise, given that the FRIGIDA complex, involved in the up-regulation of FLC, recruits AtTAF14 homolog, plus some other components of the SWR1 complex such as SWC6 and YAF9, these results provide an insight into how different chromatin remodelling mechanisms control the floral transition through the transcriptional regulation of FLC. | |
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Internacional
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ISBN
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Tipo de Tesis
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Doctoral |
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Calificación
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Sobresaliente |
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Fecha
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26/04/2013 |