The sea urchin metallothionein system : Comparative evaluation of the SpMTA and SpMTB metal-binding preferences
Tomàs i Giner, Mireia (Universitat Autònoma de Barcelona. Departament de Química)
Domènech, Jordi (Universitat de Barcelona. Departament de Genètica)
Capdevila Vidal, Mercè (Universitat Autònoma de Barcelona. Departament de Química)
Bofill Arasa, Roger (Universitat Autònoma de Barcelona. Departament de Química)
Atrian i Ventura, Sílvia (Universitat de Barcelona. Departament de Genètica)

Data:	2013
Resum:	Metallothioneins (MTs) constitute a superfamily of ubiquitous metal-binding proteins of low molecular weight and high Cys content. They are involved in metal homeostasis and detoxification, amongst other proposed biological functions. Two MT isoforms (SpMTA and SpMTB) have been reported in the echinoderm Strongylocentrotus purpuratus (sea urchin), both containing 20 Cys residues and presenting extremely similar sequences, although showing distinct tissular and ontogenic expression patterns. Although exhaustive information is available for the Cd(II)-SpMTA complex, this including the full resolution of its 3D structure, no data has been reported concerning either SpMTA Zn(II) and Cu(I) binding properties, or the characterization of SpMTB at protein level. In this work, both the SpMTA and SpMTB isoforms, as well as their separate α and β domains, have been recombinantly synthesized in the presence of Zn(II), Cd(II) or Cu(II), and the corresponding metal complexes have been analyzed using electrospray mass spectrometry, and CD, ICP-AES and UV-vis spectroscopies. The results clearly show a better performance of isoform A when binding Zn(II) and Cd(II), and of isoform B when coordinating Cu(I). Thus, our results confirm the differential metal binding preference of SpMTA and SpMTB, which, together with the reported induction pattern of the respective genes, highlights how also in Echinodermata the MT polymorphism may be linked to the evolution of different physiological roles. ▸ SpMTA shows a better performance when binding Zn(II) and Cd(II). ▸ SpMTB shows a better performance when binding Cu(I). ▸ The β domain is responsible for the lower divalent metal binding capacity of SpMTB. ▸ The α and β domains contribute to the enhanced capacity of SpMTB for Cu(I) binding.
Ajuts:	Ministerio de Ciencia e Innovación BIO2012-39682-C02-01 Ministerio de Ciencia e Innovación BIO2012-39682-C02-02
Drets:	Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial, la distribució, i la comunicació pública de l'obra, sempre que no sigui amb finalitats comercials, i sempre que es reconegui l'autoria de l'obra original. No es permet la creació d'obres derivades.
Llengua:	Anglès
Document:	Article ; recerca ; Versió publicada
Matèria:	Metallohionein ; Echinodermata ; Cadmium ; Copper ; Zinc
Publicat a:	FEBS Open Bio, Vol. 3, issue 1 (Jan. 2013) , p. 89-100, ISSN 2211-5463

DOI: 10.1016/j.fob.2013.01.005
PMID: 23847757

12 p, 1.8 MB

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