title: Directed evolution of a yeast arsenate reductase into a protein-tyrosine phosphatase.
abstract: Arsenic, which is ubiquitous in the environment and comes from both geochemical and anthropogenic sources, has become a worldwide public health problem. Every organism studied has intrinsic or acquired mechanisms for arsenic detoxification. In Saccharomyces cerevisiae arsenate is detoxified by Acr2p, an arsenate reductase. Acr2p is not a phosphatase but is a homologue of CDC25 phosphatases. It has the HCX5R phosphatase motif but not the glycine-rich phosphate binding motif (GXGXXG) that is found in protein-tyrosine phosphatases. Here we show that creation of a phosphate binding motif through the introduction of glycines at positions 79, 81, and 84 in Acr2p resulted in a gain of phosphotyrosine phosphatase activity and a loss of arsenate reductase activity. Arsenate likely achieved geochemical abundance only after the atmosphere became oxidizing, creating pressure for the evolution of an arsenate reductase from a protein-tyrosine phosphatase. The ease by which an arsenate reductase can be converted into a protein-tyrosine phosphatase supports this hypothesis.
authors.affiliation: Department of Biochemistry and Molecular Biology, Wayne State University School of Medicine, Detroit, Michigan 48201, USA. rmukhopa@med.wayne.edu
authors.forename: Rita
authors.initials: R
authors.lastname: Mukhopadhyay
authors.forename: Yao
authors.initials: Y
authors.lastname: Zhou
authors.forename: Barry P
authors.initials: BP
authors.lastname: Rosen
mesh_terms: D053502:Arsenate Reductases; D001149:Arsenates / Q000494:pharmacology; D053501:Arsenite Transporting ATPases; D001665:Binding Sites / Q000235:genetics; D019020:Directed Molecular Evolution; D025141:Drug Resistance, Fungal; D006540:Herbicides / Q000494:pharmacology; D016623:Ion Pumps / Q000235:genetics / Q000378:metabolism*; D009097:Multienzyme Complexes / Q000235:genetics / Q000378:metabolism*; D010710:Phosphates / Q000378:metabolism; D017027:Protein Tyrosine Phosphatases / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins
chemical_list: D001149:Arsenates; D006540:Herbicides; D016623:Ion Pumps; D009097:Multienzyme Complexes; D010710:Phosphates; D029701:Saccharomyces cerevisiae Proteins; C506971:ARR2 protein, S cerevisiae; D053502:Arsenate Reductases; D017027:Protein Tyrosine Phosphatases; D053501:Arsenite Transporting ATPases; C025657:arsenic acid