FIGURE 3.

Reduced Fet3p activity in kha1Δ cells and its recovery by surplus copper or K⁺ in the growth media. A, C, and D, chromosomal FET3 in WT control and kha1Δ cells was fused with c-myc epitope. Whole cell extracts were subjected to Fet3p oxidase assays and Western blotting using anti-myc antibodies. The numbers indicate relative oxidase activities (n = 4). The experiments were conducted without and with supplementation of K₂SO₄ (100 mm) (C) or CuSO₄ (25 μm) (D) in the media for 30 min before collecting cells. B, KHA1 knock-out does not affect Sod1p activities. WT and kha1Δ strains were cultured at mid-log phase in YPD media with and without supplementation of copper chelator, BCS. Total cell lysates were subjected to in-gel Sod1p activity assays. E, enzymatic activities of a laccase of P. coccineus in the yeast S. cerevisiae. Representative figures of at least four colonies are presented. The white hollow around the growing cells reflects laccase activities. The data represent the average ± S.D. (n = 4). One (*) and two (**) asterisks indicate p < 0.05 and p < 0.01, respectively, compared with WT cells expressing empty vector or without K⁺ and copper co-culture.