Expression, Characterization and Regulation of a Saccharomyces cerevisiae Monothiol Glutaredoxin (Grx6) Gene in Schizosaccharomyces pombe

Glutaredoxins (Grxs), also known as thioltransferases (TTases), are thiol oxidoreductases that regulate cellular redox state in a variety of organisms. In the budding yeast Saccharomyces cerevisiae, Grx1 and 2 are cytosolic dithiol Grxs, while Grx3, 4 and 5 are monothiol Grxs. A gene encoding a new monothiol Grx, Grx6, was cloned from the genomic DNA of S. cerevisiae by PCR. Its DNA sequence contains 1,080 bp, and encodes a putative protein of 203 amino acid residues containing Cys-Phe-TyrSer at the active site. Grx6 is similar to other monothiol Grxs in the same organism and to Grx3 in the fission yeast Schizosaccharomyces pombe. and its predicted three-dimensional structure resembles that of S. pombe Grx3. S. pombe cells harboring plasmid pFGRX6 containing the Grx6 gene had about 1.3-fold elevated Grx activity in the exponential phase, and grew better than the control cells under some stressful conditions. Synthesis of β-galactosidase from a Grx6-lacZ fusion gene in S. pombe was enhanced by potassium chloride, aluminum chloride and heat (37℃) treatment. S. pombe cells harboring plasmid pFGRX6 had elevated ROS levels whereas S. pombe cells harboring extra copies of Grx3 had reduced ROS levels.