Mutated Yeast Heat Shock Transcription Factor Exhibits Elevated Basal Transcriptional Activation and Confers Metal Resistance (∗)

• Published in: The Journal of biological chemistry Vol. 270; no. 42; pp. 25079 - 25086
• Main Authors: Sewell, Andrew K., Yokoya, Fumihiko, Yu, Wei, Miyagawa, Terumi, Murayama, Tetsuo, Winge, Dennis R.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 20.10.1995; American Society for Biochemistry and Molecular Biology
• Subjects: ACTIVIDAD ENZIMATICA; ACTIVITE ENZYMATIQUE; ADN RECOMBINADO; ADN RECOMBINE; Base Sequence; BETA GALACTOSIDASA; BETA GALACTOSIDASE; CADMIO; CADMIUM; Cadmium - pharmacology; CALOR; CHALEUR; Cloning, Molecular; DNA - metabolism; DNA-Binding Proteins - genetics; DNA-Binding Proteins - physiology; Escherichia coli; ESTRES TERMICO; EXPRESION GENICA; EXPRESSION DES GENES; GENE; GENES; GENETICA; GENETIQUE; Heat-Shock Proteins; Hot Temperature; METALLOPROTEINE; Metallothionein - genetics; METALPROTEINAS; Molecular Sequence Data; MUTACION; MUTANT; MUTANTES; MUTATION; RESISTANCE A LA TEMPERATURE; RESISTANCE AUX FACTEURS NUISIBLES; RESISTENCIA A AGENTES DANINOS; RESISTENCIA A LA TEMPERATURA; SACCHAROMYCES CEREVISIAE; Saccharomyces cerevisiae - drug effects; Saccharomyces cerevisiae - genetics; Saccharomyces cerevisiae Proteins; STRESS THERMIQUE; THIONEINE; TIONEINA; TRANSCRIPCION; TRANSCRIPTION; Transcription Factors - genetics; Transcription Factors - physiology; Transcriptional Activation
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.270.42.25079

Cadmium-resistant Saccharomyces cerevisiae strain 301N exhibits high basal as well as cadmium-induced expression of the CUP1 metallothionein gene. Since regulation of CUP1 is usually restricted to copper ions, our goal was to identify the factor responsible for the high metallothionein levels in strain 301N. The gene responsible for the observed phenotype is a spontaneously mutated heat shock transcription factor gene (HSF1). A double, semidominant HSF1 mutant with substitutions at codons 206 and 256 within the DNA-binding domain of the heat shock factor (HSF) confers two phenotypes. The first phenotype is elevated transcriptional activity of the HSF mutant (HSF301), which results in constitutive thermotolerance. A second HSF301 phenotype is enhanced binding affinity for the heat shock element (HSE) within the CUP1 5′-sequences, resulting in high basal transcription of metallothionein. The CUP1 HSE is a minimal heat shock element containing only two perfectly spaced inverted repeats of the basic nGAAn block. Cells containing HSF301 are resistant to cadmium salts. The single R206S mutation is responsible for the high affinity binding to the CUP1 HSE. In addition, the R206S HSF substitution exhibits constitutive transcriptional activation from a consensus HSE (HSE2). The F256Y substitution in HSF attenuates the effects of R206S on the consensus HSE2, but not on the CUP1 HSE.