[Yeast] CUP1 promoter and Copper toxicity to S. cerevisae

[Jingjing Sun]

Dear Yeast Netters,
There is a question regarding CUP1 promoter:
I placed a gene of interest under the CUP1 promoter. When the cupric 
sulphate is above 100 uM, I start to see the dark cell sediment on the 
tube bottom. I assume this is due to the copper toxicity. When the 
inducer goes up to 500 uM, I saw improved protein production, but the 
cell growth was inhibited a lot, and i saw debris by Flow cytometry.
However, I checked with a paper ( Hottiger, T., Furst, P., Pohlig, G. & 
Heim, J. Physiological Characterization of the Yeast Metallothionein 
(Cup1) Promoter, and Consequences of Overexpressing Its Transcriptional 
Activator, Ace1. Yeast 10, 283-296 (1994)), the amount of cupric 
sulphate was much lower than the toxicity limit (2mM).

Would you please share with me your experience on CUP1 promoter? Is 
there any substitute to replace CUP1 promoter if the toxicity is a 
really problem?

Thanks a lot!

Jingjing