Stable nucleosome positioning and complete repression by the yeast alpha 2 repressor are disrupted by amino-terminal mutations in histone H4.
Nucleosomes are positioned in the presence of the yeast repressor alpha 2 in minichromosomes containing the alpha 2 operator and on the promoters of a-cell-specific genes regulated by alpha 2. To investigate the possibility that alpha 2 directs nucleosome position through an interaction with a component of the core particle, we analyzed chromatin structures adjacent to the operator in alpha cells containing mutations in the amino-terminal region of histone H4. Deletion or point mutation of specific amino acids in histone H4 altered the location and/or stability of nucleosomes adjacent to the alpha 2 operator. These changes in chromatin structure were accompanied by partial derepression of a beta-galactosidase reporter construct under alpha 2 control, even though alpha 2 remained bound to its operator sequence. Our data suggest that complete repression by alpha 2 requires stable positioning of nucleosomes in promoter regions and this positioning involves the conserved amino-terminal region of histone H4.
Roth
S Y
SY
Laboratory of Cellular and Developmental Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892.
Shimizu
M
M
Johnson
L
L
Grunstein
M
M
Simpson
R T
RT
D001483:Base Sequence; D002843:Chromatin; D002872:Chromosome Deletion; D015825:Chromosomes, Fungal; D016172:DNA Fingerprinting; D004271:DNA, Fungal / Q000235:genetics; D005800:Genes, Fungal; D016153:Genes, Suppressor; D006657:Histones / Q000235:genetics*; D008969:Molecular Sequence Data; D009154:Mutation; D009707:Nucleosomes; D009875:Operator Regions, Genetic; D010957:Plasmids; D011401:Promoter Regions, Genetic; D012441:Saccharomyces cerevisiae / Q000235:genetics*
D002843:Chromatin; D004271:DNA, Fungal; D006657:Histones; D009707:Nucleosomes