IDENTIFICATION
OF REGULATORY ELEMENTS IN STRESS INDUCIBLE EPIMERASE PROMOTER FROM FILAMENTOUS
FUNGUS Rhizopus nigricans
Institute
of Biochemistry, Faculty of Medicine, University of Ljubljana, Vrazov trg 2,
1000 Ljubljana, Slovenia
Our previous studies revealed that exposure of filamentous fungus Rhizopus nigricans (R. nigricans) to different stressors up-regulates the expression of cytosolic hsp70 and epimerase genes. Analysis of the epimerase gene promoter showed that it includes putative binding sites for transcriptional activators and repressors, which could be involved in the control of gene expression. We proposed that two types of regulatory elements could regulate the epimerase gene induction during heat shock: two putative heat shock elements (HSE) and possibly STRE, present in many promoters of yeast Saccharomyces cerevisiae (S. cerevisiae) genes which are induced in different stress conditions, including heat shock. The aim of the present study was to investigate in vitro the two types of promoter regulatory elements, possibly involved in activation of the epimerase gene during heat shock. The results obtained with electrophoretic mobility shift assay (EMSA) showed that in the fungus R. nigricans the epimerase gene is induced during heat shock via HSF-independent mechanism and that heat shock activates transcription factors capable of binding to putative STRE regulatory element.