A YARE-like element as the binding site for specific KlHIS4 transcriptional regulators and its implication in cadmium toxicity

The YARE (Yeast AP1-Recognition Element) is the DNA binding site for YAp1 and YAp2 transcriptional activators in the presence of cadmium. The roles of three sequences matching the YARE consensus on the KlHIS4 promoter are analysed to determine their implication in cadmium transcriptional regulation. A specific band, Cd2, is characterised by EMSA in the region encompassing positions -283 to -276, which disappears in the presence of cadmium or when the YARE consensus is mutated. The factor causing Cd2 is named CSP1 (Cadmium Sensitive Protein 1). The binding of a second factor (P3) producing the band Cd3, also dependent on the YARE consensus, but insensitive to cadmium, is also characterised in the same region. The gel-shift pattern of region -384 to -323 with no YARE consensus is also altered by cadmium, thus, the cadmium transcriptional response of KlHIS4 appears to be modulated by multiple promoter elements. The presence of YARE regulatory elements is not a guarantee of a specific cadmium transcriptional regulation in K. lactis.