Effects of Sin- versions of histone H4 on yeast chromatin structure and function

UMMS Affiliation

Program in Molecular Medicine and Department of Biochemistry and Molecular Biology

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Document Type



Chromatin; Chromosomes, Fungal; DNA, Fungal; DNA, Superhelical; Gene Expression Regulation, Fungal; Genes, Fungal; Histones; Membrane Transport Proteins; Micrococcal Nuclease; Mutation; *Phosphate Transport Proteins; Recombinant Fusion Proteins; Regulatory Sequences, Nucleic Acid; Site-Specific DNA-Methyltransferase (Adenine-Specific); Transcription, Genetic; Yeasts


Life Sciences | Medicine and Health Sciences


Previous studies have identified single amino acid changes within either histone H3 or H4 (Sin- versions) that allow transcription in the absence of the yeast SWI-SNF complex. The histone H4 mutants are competent for nucleosome assembly in vivo, and the residues that are altered appear to define a discrete domain on the surface of the histone octamer. We have analyzed the effects of the Sin- versions of histone H4 on transcription and chromatin structure in vivo. These histone H4 mutants cause an increased accessibility of nucleosomal DNA to Dam methyltransferase and to micrococcal nuclease. Sin- derivatives of histone H4 also grossly impair the ability of nucleosomes to constrain supercoils in vivo. Nucleosome-mediated repression of the PHO5 gene is severely impaired by these histone H4 mutants; PHO5 expression is derepressed to 31% of the wild-type induced level. In contrast to the induction caused by nucleosome depletion, full PHO5 derepression by Sin- versions of histone H4 requires upstream regulatory elements. In addition, Sin- derivatives of histone H4 do not activate expression from CYC1 or GAL1 promoters that lack UAS elements. We propose that these Sin- mutations alter histone-DNA contact residues that play key roles in restricting the accessibility of nucleosomal DNA to transcription factors.

DOI of Published Version



EMBO J. 1997 Apr 15;16(8):2086-95. Link to article on publisher's site

Journal/Book/Conference Title

The EMBO journal

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Link to Article in PubMed

PubMed ID