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

Eurobic9, 2-6 September, 2008, Wrocław, Poland
P14. New Insights into the Classification of Metallothioneins: a Gradation
Between Zn- and Cu-thionein Features
R. Bofill a , S. Atrian b , M. Capdevila a
a
Departament de Química, Universitat Autònoma de Barcelona, Facultat de Ciències, 08193, Bellaterra
(Catalonia), Spain
e-mail: roger.bofill@uab.cat
b
Departament de Genètica, Universitat de Barcelona, Avda. Diagonal 645, 08028, Barcelona, Spain
Over the last years we studied many recombinant MTs, from several phyla. A comprehensive consideration of
all our new data allows us a fine-tuning of our previous MT classification [1] by considering a gradation between
Zn- and Cu-thioneins (Zn-th & Cu-th). We formerly proposed as Zn-th those that required Zn(II) for in vivofolding
in the presence of high copper, while Cu-th yielded homometallic Cu-MT species. Now, we propose a
gradient in the Cu-th character, since homometallic Cu-species are obtained only under low aeration of cultures
for some of them, but both under low and high O2 conditions for others, thus the latter MTs exhibiting a stronger
Cu-th character. Noteworthy, all the in vivo-obtained Cu-MT species can be reproduced by Zn/Cu in vitroreplacement,
the weaker the Cu-th character of an MT, the lesser the Cu(I) eq required to in vitro reproduce the
in vivo-obtained complexes.
The gradation in the Zn-th character of MTs is envisaged from their recombinant synthesis in Zn- and Cd-rich
media. We attribute a major Zn-th character to those MTs that either give rise to Zn, Cd-MT complexes when
synthesized in Cd-supplemented cultures, or show a clear in vitro reluctance to total Zn/Cd exchange.
Interestingly, the gradation from both ends (strict Zn-ths and Cu-ths) converge in a group of MTs with
intermediate properties, which have in common the formation of recombinant Cd-S 2- -MT species, with amounts
of sulfide increasing in direct relation to their Cu-th character.
References:
[1] A New Insight into Metallothionein (MT) Classification and Evolution. The in vivo and in vitro metal binding
features of Homarus americanus recombinant MT, M. Valls, R. Bofill, R. González-Duarte, P. González-Duarte,
M. Capdevila, S. Atrian, J. Biol. Chem., 276 (35), 32835-32843 (2001)
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