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The ATP-dependent Chromatin Remodeling Enzyme Fun30 Represses Transcription by Sliding Promoter-proximal Nucleosomes

Year: 2013

Type: article

Abstract: The evolutionarily conserved ATP-dependent chromatin remodeling enzyme Fun30 has recently been shown to play important roles in heterochromatin silencing and DNA repair. However, how Fun30 remodels nucleosomes is not clear. Here we report a nucleosome sliding activity of Fun30 and its role in transcriptional repression. We observed that Fun30 repressed the expression of genes involved in amino acid and carbohydrate metabolism, the stress response, and meiosis. In addition, Fun30 was localized at the 5′ and 3′ ends of genes and within the open reading frames of its targets. Consistent with its role in gene repression, we observed that Fun30 target genes lacked histone modifications often associated with gene activation and showed an increased level of ubiquitinated histone H2B. Furthermore, a genome-wide nucleosome mapping analysis revealed that the length of the nucleosome-free region at the 5′ end of a subset of genes was changed in Fun30-depleted cells. In addition, the positions of the −1, +2, and +3 nucleosomes at the 5′ end of target genes were shifted significantly, whereas the position of the +1 nucleosome remained largely unchanged in the fun30 Δ mutant. Finally, we demonstrated that affinity-purified, single-component Fun30 exhibited a nucleosome sliding activity in an ATP-dependent manner. These results define a role for Fun30 in the regulation of transcription and indicate that Fun30 remodels chromatin at the 5′ end of genes by sliding promoter-proximal nucleosomes. Background: The conserved ATP-dependent chromatin remodeling enzyme Fun30 regulates heterochromatin silencing and DNA repair. Results: Gene expression is up-regulated, and nucleosome positioning is altered in fun30 Δ cells, and purified Fun30 slides nucleosome in vitro . Conclusion: Fun30 represses gene expression by sliding promoter-proximal nucleosomes. Significance: The function of Fun30 is expanded to regulation of transcription and chromatin remodeling by nucleosome sliding.

Source: Journal of Biological Chemistry

DOI: 10.1074/jbc.m113.471979