ISBN: 978-83-60043-10-3 - eurobic9

Eurobic9, 2-6 September, 2008, Wrocław, Poland
P147. How Does CUP1 Cope with Cd(II) or Zn(II) Instead of Cu(I)?
R. Orihuela a , F. Monteiro b , S. Atrian b , M. Capdevila a
a Departament de Química, Universitat Autònoma de Barcelona, , 08193, Bellaterra, Spain,
b Departament de Genètica, Universitat de Barcelona, , 08028, Barcelona, Spain
e-mail: ruben.orihuela@uab.es
Metallothioneins (MTs) are ubiquitous, small cysteine-rich proteins that bind d 10 heavy metal ions such as the
essential Cu(I) and Zn(II) or the toxic Cd(II) and Hg(II).
CUP1 is the paradigmatic copper-thionein from the yeast Saccharomyces cerevisiae, whose gene responds to
copper but not to cadmium overload.
In this work we have used spectroscopic and spectrometric techniques to characterize the copper, zinc, and
cadmium complexes formed by CUP1 recombinantly synthesized in E. coli.
Furthermore, we have studied native Cd-CUP1 complexes produced by the mutant strain 301N of S. cerevisiae,
where a promoter mutation enables a high cadmium-induced CUP1 expression [1, 2].
Preliminary results corroborate the literature reporting the coordination of 8 copper ions by CUP1, and the
features of the Cu-CUP1 species [3]. The metalated protein recovered from zinc supplemented cultures was
found to contain 4 metal ions. The cadmium complexes from enriched cadmium cultures contain a variable
number of Cd(II) ions together with a considerable amount of sulphide ligands.
Owing to the fact that CUP1 is the Cu-thionein par excellence, the comparison of the recombinant (E.coli) Cd-
CUP1 with the native Cd-CUP1 preparations will reveal if the native metal-protein complexes have the ability to
harbour non proteic ligands, as we have previously described happening when recombinant metallothioneins are
forced to coordinate their “non-preferred” metal ions [4].
References:
[1] A.K. Sewell, F. Yokoya, W. Fu, T. Miyagawa, T. Murayama, D.R. Winge, The Journal of Biological
Chemistry, 1995, 270, 25079-25086.
[2] M. Inouhe, M. Hiyama, H. Tohoyama, M. Joho, T. Murayama, Bioquimica et Biophysica Acta, 1989, 993,
51-55.
[3] D.R. Winge, K.B. Nielson, W.R. Gray, D.H. Hamer, The Journal of Biological Chemistry, 1985, 260, 14464-
14470.
[4] M. Capdevila, J. Domenech, A. Pagani, L. Tío, L. Villareal, S. Atrian, Angew. Chem. Int. Ed., 2005, 44,
4618-4622.
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