Does Variation of the Inter-Domain Linker Sequence Modulate the Metal Binding Behaviour of Helix pomatia Cd-Metallothionein?

International Journal of Molecular Sciences

Selene Gil-Moreno⁴  Elena Jiménez-Martí¹  Òscar Palacios⁴  Oliver Zerbe²  Reinhard Dallinger³  Mercè Capdevila⁴  Sílvia Atrian¹ 

[1] Departament de Genètica, Facultat de Biologia, Universitat de Barcelona, Av. Diagonal 643, E-08028 Barcelona, Spain;Institute of Organic Chemistry, University of Zurich, 8057 Zurich, Switzerland;Institute of Zoology, University of Innsbruck, Technikerstraße 25, A-6020 Innsbruck, Austria;Departament de Química, Facultat de Ciències, Universitat Autònoma de Barcelona, E-08193 Cerdanyola del Vallès, Spain;

关键词: Cd-isoform;    domain linker sequence;    Helix pomatia;    metallothionein;    metal binding;   

DOI  :  10.3390/ijms17010006

来源: mdpi

【 摘 要 】

Snail metallothioneins (MTs) constitute an ideal model to study structure/function relationships in these metal-binding polypeptides. Helix pomatia harbours three MT isoforms: the highly specific CdMT and CuMT, and an unspecific Cd/CuMT, which represent paralogous proteins with extremely different metal binding preferences while sharing high sequence similarity. Preceding work allowed assessing that, although, the Cys residues are responsible for metal ion coordination, metal specificity or preference is achieved by diversification of the amino acids interspersed between them. The metal-specific MT polypeptides fold into unique, energetically-optimized complexes of defined metal content, when binding their cognate metal ions, while they produce a mixture of complexes, none of them representing a clear energy minimum, with non-cognate metal ions. Another critical, and so far mostly unexplored, region is the stretch linking the individual MT domains, each of which represents an independent metal cluster. In this work, we have designed and analyzed two HpCdMT constructs with substituted linker segments, and determined their coordination behavior when exposed to both cognate and non-cognate metal ions. Results unequivocally show that neither length nor composition of the inter-domain linker alter the features of the Zn(II)- and Cd(II)-complexes, but surprisingly that they influence their ability to bind Cu(I), the non-cognate metal ion.

【 授权许可】

CC BY   
© 2015 by the authors; licensee MDPI, Basel, Switzerland.