Open AccessHigh-Resolution Structural Analysis of Chromatin at Specific Loci: Saccharomyces cerevisiae Silent Mating-Type Locus HMRa
Author(s) -
Anish Ravindra,
Kerstin Weiß,
Robert T. Simpson
Publication year - 1999
Publication title -
molecular and cellular biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.14
H-Index - 327
eISSN - 1067-8824
pISSN - 0270-7306
DOI - 10.1128/mcb.19.12.7944
Subject(s) - biology , locus (genetics) , chromatin , genetics , nucleosome , mating type , micrococcal nuclease , saccharomyces cerevisiae , gene
Genetic and biochemical evidence implicates chromatin structure in the silencing of the two quiescent mating-type loci near the telomeres of chromosome III in yeast. With high-resolution micrococcal nuclease mapping, we show that theHMR a locus has 12 precisely positioned nucleosomes spanning the distance between the E and I silencer elements. The nucleosomes are arranged in pairs with very short linkers; the pairs are separated from one another by longer linkers of ∼20 bp. Both the basic amino-terminal region of histone H4 and the silent information regulator protein Sir3p are necessary for the organized repressive chromatin structure of the silent locus. Compared toHMR a, only small differences in the availability of the TATA box are present for the promoter in the cassette at the activeMAT a locus. Features of the chromatin structure of this silent locus compared to the previously studiedHML α locus suggest differences in the mechanisms of silencing and may relate to donor selection during mating-type interconversion.