Multiple protein-DNA interactions over the yeast HSC82 heat shock gene promoter.
We have utilized DNase I and micrococcal nuclease (MNase) to map the chromatin structure of the HSC82 heat shock gene of Saccharomyces cerevisiae. The gene is expressed at a high basal level which is enhanced 2-3-fold by thermal stress. A single, heat-shock invariant DNase I hypersensitive domain is found within the HSC82 chromosomal locus; it maps to the gene's 5' end and spans 250 bp of promoter sequence. DNase I genomic footprinting reveals that within this hypersensitive region are four constitutive protein-DNA interactions. These map to the transcription initiation site, the TATA box, the promoter-distal heat shock element (HSE1) and a consensus GRF2 (REB1/Factor Y) sequence. However, two other potential regulatory sites, the promoter-proximal heat shock element (HSE0) and a consensus upstream repressor sequence (URS1), are not detectably occupied under either transcriptional state. In contrast to its sensitivity to DNAase I, the nucleosome-free promoter region is relatively protected from MNase; the enzyme excises a stable nucleoprotein fragment of approximately 210 bp. As detected by MNase, there are at least two sequence-positioned nucleosomes arrayed 5' of the promoter; regularly spaced nucleosomes exhibiting an average repeat length of 160-170 bp span several kilobases of both upstream and downstream regions. Similarly, the body of the gene, which exhibits heightened sensitivity to DNase I, displays a nucleosomal organization under both basal and induced states, but these nucleosomes are not detectably positioned with respect to the underlying DNA sequence and may be irregularly spaced and/or structurally altered. We present a model of the chromatin structure of HSC82 and compare it to one previously derived for the closely related, but differentially regulated, HSP82 heat shock gene.
Erkine
A M
AM
Department of Biochemistry and Molecular Biology, Louisiana State University Medical Center, Shreveport 71130, USA.
Adams
C C
CC
Gao
M
M
Gross
D S
DS
D001483:Base Sequence; D015152:Blotting, Northern; D002843:Chromatin / Q000235:genetics*; D002874:Chromosome Mapping; D015825:Chromosomes, Fungal; D016384:Consensus Sequence; D017124:Conserved Sequence; D003850:Deoxyribonuclease I; D005656:Fungal Proteins / Q000235:genetics*; D005800:Genes, Fungal; D018841:HSP90 Heat-Shock Proteins; D006360:Heat-Shock Proteins / Q000235:genetics; D008836:Micrococcal Nuclease; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D012045:Regulatory Sequences, Nucleic Acid; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins
D002843:Chromatin; D005656:Fungal Proteins; C074510:HSP82 protein, S cerevisiae; D018841:HSP90 Heat-Shock Proteins; D006360:Heat-Shock Proteins; D029701:Saccharomyces cerevisiae Proteins; D003850:Deoxyribonuclease I; D008836:Micrococcal Nuclease