Jordi Domenech. Introduction to Metallothioneins
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Slide 1 of 3 |
Metallothioneins (MT) are low molecular weight, cysteine-rich proteins with an exceptional heavy-metal coordination capacity.
First purified from horse kidney in 1957, they have been reported in all animal phyla and most fungi and plants. MTs show very diverse Cys-motifs, peptide length and domain structure and have been classified in several families, mainly based on their sequence and on organism taxonomy.
In vertebrate and echinoderma MTs, a two-domains (alpha and Beta) structure have been described, similar to the disposition of two Beta domains in crustacea, while in yeast CUP1 MT, data show a one-domain structure. No more data are available on tertiary structure in MTs.
MTs bind metals through the thiol (-SH) group of their their Cys residues, and have been associated with protection against toxic metals (Cd, Hg, ...) and with homeostasis/storage/transport of physiological zinc and copper.
Other functions, such as free radical scavenging or oxidative stress protection, have also been proposed, but for the instance it is difficult to identify a main function for MTs.
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Jordi Domenech. Introduction to Metallothioneins
Go to Jordi's Metallothionein Research Page.
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Slide 2 of 3 |
MTs bind metals like Zn, Cu, Ag, Cd, Hg, Pb, Pt,...through Cys residues, exhibiting metal preferences depending on the MT, and in the distribution of the Cys residues along its primary structure.
MT metal-binding have been traditionally studied focusing on Cys distribution in the primary structure (Cys motifs), and mainly in vertebrate MTs.
Therefore, currently, there are few data neither on the participation of ligands other than Cys in metal-MT complexes, nor on the functional features of Cys domains other than those present in vertebrate MTs.
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Jordi Domenech. Introduction to Metallothioneins
Go to Jordi's Metallothionein Research Page.
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Slide 3 of 3 |
As there is an important heterogeneity and no homology among the amino acid MT sequences of the invertebrate and plant MTs, extrapolation from the results of MTs from other taxa is not suitable to construct a model for these proteins.
Additional experimental information is completely necessary to propose a functional model for MTs.
My research subject deals with the relationship between the primary structure of plant, Protozoa and Invertebrate Metallothioneins and several aspects of their molecular features, including peptide folding, metal-binding abilities, metal coordination preferences and structure, in order to get information about the chemical and geometric functional constraints defininf the evolutionary paths of this family of proteins.
The MT peculiar capabilities can serve also biotechnological purposes as peptide design for bioremediation.
