Two Distinct Upstream Regions Are Involved in Expression of the Catalase Gene in Schizosaccharomyces pombe in Response to Oxidative Stress

: The DNA region responsible for the induction of the catalase gene of Schizosaccharomyces pombe in response to oxidative stress was determined by constructing a series of deletions in the 5'-flanking region of the gene. Cells having deletion -672 (numbered with the transcription start site as +1) to -111 showed no significant difference in catalase expression from the wild-type cells. Cells having deletion -672 to -89 showed reduced basal expression of the catalase mRNA, but retained the ability of induction in response to oxidative stress. Cells having deletion -672 to -55 completely lost the ability to express the catalase mRNA. These results suggested that two regions, -89 to -55 and -111 to -89, are involved in expression of the catalase gene. The DNA region of -89 to -55 overlapped with the Atf1 binding sequence. The Atf1 is a bZIP transcription factor with an important role in stress response under the control of the Spc1 mitogen activated protein (MAP) kinase. Introduction of the atf1(-) or spc1(-) mutation into the mutant having a deletion in -672 to -89 completely abolished the expression of the catalase mRNA. This result indicated that the Spc1-Atf1 cascade is involved in expression of the catalase gene through the region of -89 to -55. In mutants spc1(-) and atf1(-), basal expression and induction by hydrogen peroxide of catalase mRNA were observed. These results revealed that not only the Atf1 binding site but also another DNA element independent of the Spc1-Atf1 pathway is involved in the expression of the catalase gene in response to oxidative stress in S. pombe. Proteins that bound specifically to each DNA element existed in the cell extract of the wild-type S. pombe.