An n-alkane-responsive promoter element found in the gene encoding the peroxisomal protein of Candida tropicalis does not contain a C₆ zinc cluster DNA-binding motif

When an asporogenic diploid yeast, Candida tropicalis, is cultivated on n-alkane, the expression of the genes encoding enzymes of the peroxisomal β- oxidation pathway is highly induced. An upstream activation sequence (UAS) which can induce transcription in response to n-alkane (UAS(ALK)) was identified on the promoter region of the peroxisomal 3-ketoacyl coenzyme A (CoA) thiolase gene of C. tropicalis (CT-T3A). The 29-bp region (from -289 to -261) present upstream of the TATA sequence was sufficient to induce n- alkane-dependent expression of a reporter gene. Besides n-alkane, UAS(ALK- dependent) gene expression also occurred in the cells grown on oleic acid. Several kinds of mutant UAS(ALK) were constructed and tested for their UAS activity. It was clarified that the important nucleotides for UAS(ALK) activity were located within 10-bp region from -273 to -264 (5'-TCCTGCACAC- 3'). This region did not contain a CGG triplet and therefore differed from the sequence of the oleate-response element (ORE), which is a UAS found on the promoter region of 3-ketoacyl-CoA thiolase gene of Saccharomyces cerevisiae. Similar sequences to UAS(ALK) were also found on several peroxisomal enzyme-encoding genes of C. tropicalis.