Yeast copper

Unlike the Cd, Zn-thioneins, the respective copper-thiolate proteins were much more susceptible to oxidation. The binding energy value of the S2p core electrons of yeast copper thionein lies at 162.0 eV (Fig. 5). Ageing of protein samples or the addition of substoichiometric concentrations of H2O2 give rise to the appearence to transient oxidation states including RSSR, RSO" and sulphonic acid. The copper thiolate... 

The mechanism by which MTF-1 facilitates zinc-induction of metallothionein promoter through the MREs is not known, but several models have been proposed. First, zinc may act as a coinducer by binding to MTF-1 and creating an allosteric change, allowing MTF-1 to bind to the MREs. The model proposed for mammalian MTF-l/MRE interaction has already been proven for yeast copper metallothionein systems (Furst et al., 1988). Another possibility may be that, under normal conditions, an inhibitor binds MTF-1. When an influx of zinc occurs, MTF-1 binds the zinc, undergoes a conformational change and is released from the inhibitor. The protein would then have the ability to bind to the MREs. Finally, upon an increase in intracellular zinc concentration, a specific coactivator may bind zinc and interact with MTF-1 to maximally induce transcription. 

Ccc2a Yeast copper Reduced apo. IfVq NMR Band et al., 2001... 

Atxl Yeast copper chaperone to Oxidized apo (1.20 A) lcc7 X-ray Rosenzweig et al., 1999... 

In dicotyledon plants, like Arabidopsis, acidification of the soil would result in an increase in the solubility of both zinc and copper. Cu is taken up by the Cu" " transporter COPTl, the Arabidopsis orthologue of the yeast copper transporter CTRl and is probably reduced by FR02, which is also responsible for iron reduction. Zn is most likely taken up by members of the ZIP family, some of which are root specific, while others are found in both roots and shoots. 

N] Ccc2A apo, yeast copper transporter domain [N] Atxl Cu, yeast metallochaperone 72 35 215... 

Gralla EB, Thiele DJ, Silar P, Valentine JS. ACE1, a copper-dependent transcription factor, activates expression of the yeast copper, zinc superoxide dismutase gene. Proc Natl Acad Sci USA 88 8558-8562, 1991. 

Lu, Y. Roe, J. A. Gralla, E. B. Valentine, J. S. Metalloprotein ligand redesign characterization of copper-cysteinate proteins derived from yeast copper-zinc superoxide dismutase. In Bioinorganic Chemistry of Copper Karlin, K. D. Tyeklar, Z., Eds. Chapman and Hall New York, 1993 pp 64-77. 

Figure 1 Metal-binding site in the soluble A-terminal domain of the yeast copper transporter Ccc2 (PDB accession code IFVS). The Cu ion is coordinated by Cys 13 and Cys 16.

Figure 2 Metal-binding site in the Hg form of the yeast copper chaperone Atxl (PDB accession code 1CC8). The ion is coordinated linearly by Cys 15 and Cys 18.

Figure 7 Proposed cluster structures in yeast copper metalloregulatory proteins, (a) [Cu4(SPh)6] model compound. The phenyl rings have been omitted for clarity. Six thiolates bridge the four Cu ions. The sites in Acel and Amtl might resemble this complex, (b) Alternative structure for Acel and Amtl cluster involving eight rather than six cysteines. In this arrangement, only four thiolates are bridging, (c) Proposed structure of...

Ccc2 = yeast P-type ATPase cation transporter Atxl = yeast copper chaperone for Ccc2... 

Tamai KT, Gralla EB, Ellerby LM, Valentine JS, Thiele DJ (1993) Yeast and mammalian metallothioneins functionally substitute for yeast copper-zinc superoxide dismutase. Proc Natl Acad Sci USA 90 8013-8017... 

---