Arsenic Directly Binds to and Activates the Yeast AP-1-Like Transcription Factor Yap8

• Published in: Molecular and cellular biology Vol. 36; no. 6; pp. 913 - 922
• Main Authors: Kumar, Nallani Vijay, Yang, Jianbo, Pillai, Jitesh K., Rawat, Swati, Solano, Carlos, Kumar, Abhay, Grøtli, Morten, Stemmler, Timothy L., Rosen, Barry P., Tamás, Markus J.
• Format: Journal Article
• Language: English
• Published: United States Taylor & Francis 01.03.2016; American Society for Microbiology
• Subjects: Arsenate Reductases - genetics; Arsenic - metabolism; BASIC BIOLOGICAL SCIENCES; Basic-Leucine Zipper Transcription Factors - analysis; Basic-Leucine Zipper Transcription Factors - chemistry; Basic-Leucine Zipper Transcription Factors - metabolism; Biochemistry and Molecular Biology; Biokemi och molekylärbiologi; DNA, Fungal - genetics; DNA, Fungal - metabolism; Gene Expression Regulation, Fungal - drug effects; Membrane Transport Proteins - genetics; Microbiology; Mikrobiologi; Protein Binding; Protein Conformation - drug effects; Saccharomyces cerevisiae; Saccharomyces cerevisiae - chemistry; Saccharomyces cerevisiae - drug effects; Saccharomyces cerevisiae - genetics; Saccharomyces cerevisiae - metabolism; Saccharomyces cerevisiae Proteins - analysis; Saccharomyces cerevisiae Proteins - chemistry; Saccharomyces cerevisiae Proteins - genetics; Saccharomyces cerevisiae Proteins - metabolism; Transcription Factor AP-1 - metabolism; Transcriptional Activation - drug effects
• ISSN: 1098-5549; 0270-7306; 1098-5549
• DOI: 10.1128/MCB.00842-15

The AP-1-like transcription factor Yap8 is critical for arsenic tolerance in the yeast Saccharomyces cerevisiae . However, the mechanism by which Yap8 senses the presence of arsenic and activates transcription of detoxification genes is unknown. Here we demonstrate that Yap8 directly binds to trivalent arsenite [As(III)] in vitro and in vivo and that approximately one As(III) molecule is bound per molecule of Yap8. As(III) is coordinated by three sulfur atoms in purified Yap8, and our genetic and biochemical data identify the cysteine residues that form the binding site as Cys132, Cys137, and Cys274. As(III) binding by Yap8 does not require an additional yeast protein, and Yap8 is regulated neither at the level of localization nor at the level of DNA binding. Instead, our data are consistent with a model in which a DNA-bound form of Yap8 acts directly as an As(III) sensor. Binding of As(III) to Yap8 triggers a conformational change that in turn brings about a transcriptional response. Thus, As(III) binding to Yap8 acts as a molecular switch that converts inactive Yap8 into an active transcriptional regulator. This is the first report to demonstrate how a eukaryotic protein couples arsenic sensing to transcriptional activation.