Regulation of Thioltransferase Activity from Schizosaccharomyces pombe

Thioltransferase (TTase), also known as glutaredoxin (Grx), is an enzyme catalyzing the reduction of a variety of disulfide compounds and acting as a cofactor for various enzymes such as ribonucleotide reductase. The Schizosaccharomyces pombe cells, exponentially grown in rich medium at $30^{\circ}C$, were shifted to $20^{\circ}C$ and $35^{\circ}C$. The yeast cells, shifted to $35^{\circ}C$, showed higher TTase activity than the cells continuously grown at $30^{\circ}C$, whereas the yeast cells, shifted to $20^{\circ}C$, gave lower TTase activity. The S. pombe cells, exponentially grown in minimal medium and shifted from $30^{\circ}C$ to $35^{\circ}C$ and $40^{\circ}C$, produced higher TTase activity. When the S. pombe cells were initially incubated in rich and minimal media at three different temperatures ($25^{\circ}C$, $30^{\circ}C$ and $35^{\circ}C$), they showed higher TTase activity at higher temperature. These results suggest that the TTase activity of S. pombe is regulated by temperature.