Cantareus aspersus metallothionein metal binding abilities: The unspecific CaCd/CuMT isoform provides hints about the metal preference determinants in metallothioneins

Sílvia Pérez-Rafael, Freddy Monteiro, Reinhard Dallinger, Sílvia Atrian, Òscar Palacios, Mercè Capdevila

Research output: Contribution to journalArticleResearchpeer-review

27 Citations (Scopus)

Abstract

In Proteomics, gene/protein families including both specialized and non-specialized paralogs are an invaluable tool to study the evolution of structure/function relationships in proteins. Metallothioneins (MTs) of the pulmonate gastropod molluscs (snails) offer one of the best materials to study the metal-binding specificity of proteins, because they consist of a polymorphic system that includes members with extremely distinct metal preferences but with a high protein sequence similarity. Cantareus aspersus was the first snail where three paralogous MTs were isolated: the highly specific cadmium (CaCdMT) and copper (CaCuMT) isoforms, and an unspecific CaCd/CuMT isoform, so called because it was natively isolated as a mixed Cd and Cu complex. In this work, we have thoroughly analyzed the Zn2 +-, Cd2 +- and Cu +-binding abilities of these three CaMTs by means of the spectroscopic and spectrometric characterization of the respective recombinant, as well as in vitro-substituted, metal-complexes. The comparison with the orthologous HpMTs and the study of the isoform-determinant residues allow correlating the protein sequence variability with the coordination capabilities of these MTs. Surprisingly, the CaCuMT isoform exhibits a stronger Cu-thionein character than the HpCuMT ortholog, and the CaCd/CuMT isoform could be defined as a non-optimized Cu-thionein, which has not attained any defined functional differentiation in the framework of the snail MT gene/protein family. © 2014 Elsevier B.V.
Original languageEnglish
Pages (from-to)1694-1707
JournalBiochimica et Biophysica Acta - Proteins and Proteomics
Volume1844
Issue number9
DOIs
Publication statusPublished - 1 Jan 2014

Keywords

  • Cadmium
  • Cantareus aspersus metallothionein
  • Copper
  • Sequence determinant

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