The yeast heat shock transcription factor changes conformation in response to superoxide and temperature.
In vitro DNA-binding assays demonstrate that the heat shock transcription factor (HSF) from the yeast Saccharomyces cerevisiae can adopt an altered conformation when stressed. This conformation, reflected in a change in electrophoretic mobility, requires that two HSF trimers be bound to DNA. Single trimers do not show this change, which appears to represent an alteration in the cooperative interactions between trimers. HSF isolated from stressed cells displays a higher propensity to adopt this altered conformation. Purified HSF can be stimulated in vitro to undergo the conformational change by elevating the temperature or by exposing HSF to superoxide anion. Mutational analysis maps a region critical for this conformational change to the flexible loop between the minimal DNA-binding domain and the flexible linker that joins the DNA-binding domain to the trimerization domain. The significance of these findings is discussed in the context of the induction of the heat shock response by ischemic stroke, hypoxia, and recovery from anoxia, all known to stimulate the production of superoxide.
Lee
S
S
Departments of Biology and Chemistry, Indiana University, Bloomington, Indiana 47405-3700, USA.
Carlson
T
T
Christian
N
N
Lea
K
K
Kedzie
J
J
Reilly
J P
JP
Bonner
J J
JJ
D000595:Amino Acid Sequence; D017124:Conserved Sequence; D004247:DNA / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D019143:Evolution, Molecular; D005656:Fungal Proteins / Q000737:chemistry* / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D005978:Glutathione / Q000494:pharmacology; D006360:Heat-Shock Proteins / Q000737:chemistry* / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D008274:Magnesium / Q000378:metabolism / Q000494:pharmacology; D008969:Molecular Sequence Data; D009154:Mutation; D010100:Oxygen; D010618:Phenanthrolines / Q000737:chemistry; D011487:Protein Conformation; D029701:Saccharomyces cerevisiae Proteins; D013482:Superoxide Dismutase / Q000737:chemistry / Q000378:metabolism; D013481:Superoxides / Q000494:pharmacology*; D013696:Temperature; D014157:Transcription Factors / Q000737:chemistry* / Q000187:drug effects / Q000235:genetics / Q000378:metabolism
D004268:DNA-Binding Proteins; D005656:Fungal Proteins; C067168:HSF1 protein, S cerevisiae; D006360:Heat-Shock Proteins; D010618:Phenanthrolines; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; D013481:Superoxides; D004247:DNA; D013482:Superoxide Dismutase; D005978:Glutathione; D008274:Magnesium; D010100:Oxygen; C025205:1,10-phenanthroline