We previously isolated a gene encoding thioltransferase (TTase1) from the fission yeast Schizosaccharomyces pombe. Using a TTase-lacZ fusion plasmid, carrying a 666 bp region upstream of the translation initiation point, we found that expression of TTase1 was enhanced by metal ions, diamide and NO-generating S-nitroso-N-acetylpenicillamine (SNAP). In the present work, we examined the regulation of TTase1 expression using a series of deletion mutants and identified a negatively acting sequence between bp -469 and -339. Atf1 is required for basal expression of TTase1, and Pap1 is required for its inducible expression by mercuric chloride, diamide and SNAP. The -469 approximately -339 bp region is also responsible for mediating the inducible expression.