Formation of cadmium-binding peptide allomorphs in fission yeast

It has been reported that two kinds of Cd-binding peptide (Cd-BP1 and Cd-BP2) are induced in fission yeast upon exposure to Cd, and that they consist of the same unit peptide (cadystin), but Cd-BP1 binds 1.5 times more Cd atoms per cadystin than Cd-BP2 (Murasugi, A., Wada, C., & Hayashi, Y. (1981) J. Biochem. 90, 1561-1564). The relative amount of each allomorphic Cd-BP in the cell varied with time after induction and with the concentration of Cd in the induction medium. Further, the production of acid-labile sulfide in the cell increased greatly upon exposure to Cd and varied with time after Cd addition and with Cd concentration in the medium, as in the case of Cd-BP1. Since Cd-BP1 contains labile sulfide, the increase of labile sulfide production together with the increase of cellular Cd concentration may be the driving force to form Cd-BP1, resulting in the increase of the relative amount of Cd-BP1.