PMID:18179596

Citation	Li, C, Mueller, JE, Elfline, M and Bryk, M (2008) Linker histone H1 represses recombination at the ribosomal DNA locus in the budding yeast Saccharomyces cerevisiae. Mol. Microbiol. 67:906-19
Abstract	Several epigenetic phenomena occur at ribosomal DNA loci in eukaryotic cells, including the silencing of Pol I and Pol II transcribed genes, silencing of replication origins and repression of recombination. In Saccharomyces cerevisiae, studies focusing on the silencing of Pol II transcription and genetic recombination at the ribosomal DNA locus (rDNA) have provided insight into the mechanisms through which chromatin and chromatin-associated factors regulate gene expression and chromosome stability. The core histones, H2A, H2B, H3 and H4, the fundamental building blocks of chromatin, have been shown to regulate silent chromatin at the rDNA; however, the function of the linker histone H1 has not been well characterized. Here, we show that S. cerevisiae histone H1 represses recombination at the rDNA without affecting Pol II gene silencing. The most highly studied repressor of recombination at the rDNA is the Silent information regulator protein Sir2. We find that cells lacking histone H1 do not exhibit a premature-ageing phenotype nor do they accumulate the rDNA recombination intermediates and products that are found in cells lacking Sir2. These results suggest that histone H1 represses recombination at the rDNA by a mechanism that is independent of the recombination pathways regulated by Sir2.
Links	PubMed Online version:10.1111/j.1365-2958.2007.06101.x
Keywords	DNA Polymerase II/genetics; DNA Polymerase II/metabolism; DNA, Ribosomal/genetics; DNA, Ribosomal/metabolism; Gene Expression Regulation, Fungal; Gene Silencing; Genes, Fungal; Histones/genetics; Histones/metabolism; RNA Polymerase I/genetics; RNA Polymerase I/metabolism; Recombination, Genetic; Saccharomyces cerevisiae/genetics; Saccharomyces cerevisiae/metabolism; Saccharomyces cerevisiae Proteins/genetics; Saccharomyces cerevisiae Proteins/metabolism
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
YEAST:H1		GO:0045128: negative regulation of reciprocal meiotic recombination	ECO:0000315:		P		Figure 5 shows that "Cells lacking histone H1 (hho1Δ) form fewer Holliday junction intermediates" than the WT.	complete CACAO 11167

References

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