The change of cadystin components in Cd-binding peptides from the fission yeast during their induction by cadmium

Abstract

Previously we reported that, upon exposure to Cd, Cd-bindimg peptides (Cd-BP1 and Cd-BP2) were induced in the fission yeast and that these Cd-BPs were composed of Cd atoms and multiples of the unit peptide cadystin. In this paper, the changes of relative amounts of cadystin species in each Cd-BP were determined during their induction by Cd in the logarithmically growing yeast. The preferential syntheses of the smaller cadystin species, in the early stages of induction by Cd and of the larger cadystin species at the late stage of induction suggested the biosynthetic pathway of cadystins in the fission yeast. Binding affinities of Cd to glutathione and cadystins indicate that the larger peptides bind Cd more firmly than du the smaller peptides, coinciding with the preferential synthesis of the larger peptides with the higher concentration of Cd in the cell at the late stage of Cd induction.