Scopus: 16 citations, Google Scholar: citations,
Hints for metal-preference protein sequence determinants : different metal binding features of the five Tetrahymena thermophila metallothioneins
Espart Herrero, Anna (Universitat de Barcelona. Departament de Genètica)
Marín, Maribel (Universitat Autònoma de Barcelona. Departament de Química)
Gil Moreno, Selene (Universitat Autònoma de Barcelona. Departament de Química)
Palacios Bonilla, Òscar (Universitat Autònoma de Barcelona. Departament de Química)
Amaro, Francisco (Universidad Complutense. Departamento de Microbiología-III)
Martín-González, Ana (Universidad Complutense. Departamento de Microbiología-III)
Gutiérrez, Juan C. (Universidad Complutense. Departamento de Microbiología-III)
Capdevila Vidal, Mercè (Universitat Autònoma de Barcelona. Departament de Química)
Atrian i Ventura, Sílvia (Universitat de Barcelona. Departament de Genètica)

Date: 2015
Abstract: The metal binding preference of metallothioneins (MTs) groups them in two extreme subsets, the Zn/Cd- and the Cu-thioneins. Ciliates harbor the largest MT gene/protein family reported so far, including 5 paralogs that exhibit relatively low sequence similarity, excepting MTT2 and MTT4. In Tetrahymena thermophila, three MTs (MTT1, MTT3 and MTT5) were considered Cd-thioneins and two (MTT2 and MTT4) Cu-thioneins, according to gene expression inducibility and phylogenetic analysis. In this study, the metal-binding abilities of the five MTT proteins were characterized, to obtain information about the folding and stability of their cognate- and non-cognate metal complexes, and to characterize the T. thermophila MT system at protein level. Hence, the five MTTs were recombinantly synthesized as Zn²⁺ -, Cd²⁺ - or Cu⁺ -complexes, which were analyzed by electrospray mass spectrometry (ESI-MS), circular dichroism (CD), and UV-vis spectrophotometry. Among the Cd-thioneins, MTT1 and MTT5 were optimal for Cd²⁺ coordination, yielding unique Cd₁₇ and Cd₈ complexes, respectively and Cd- complexes, respectively. When binding Zn²⁺, they rendered a mixture of Zn-species. Only MTT5 was capable to coordinate Cu⁺, although yielding heteronuclear Zn-, Cu-species or highly unstable Cu-homometallic species. MTT3 exhibited poor binding abilities both for Cd²⁺ and for Cu⁺, and although not optimally, it yielded the best result when coordinating Zn²⁺. The two Cu-thioneins, MTT2 and MTT4 isoforms formed homometallic Cu-complexes (major Cu-MTT) upon synthesis in Cu-supplemented hosts. Contrarily, they were unable to fold into stable Cd-complexes, while Zn-MTT species were only recovered for MTT4 (major Zn-MTT4). Thus, the metal binding preferences of the five T. thermophila MTs correlate well with their previous classification as Cd- and Cu-thioneins, and globally, they can be classified from Zn/Cd- to Cu-thioneins according to the gradation: MTT1>MTT5>MTT3>MTT4>MTT2. The main mechanisms underlying the evolution and specialization of the MTT metal binding preferences may have been internal tandem duplications, presence of doublet and triplet Cys patterns in Zn/Cd-thioneins, and optimization of site specific amino acid determinants (Lys for Zn/Cd- and Asn for Cu-coordination).
Note: Número d'acord de subvenció MINECO/BIO2012-39682-C02-01
Note: Número d'acord de subvenció MINECO/BES-2010-036553)
Note: Número d'acord de subvenció MINECO/CGL2008-00317/BOS
Note: Número d'acord de subvenció AGAUR/2014/SGR-423
Rights: Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial, la distribució, la comunicació pública de l'obra i la creació d'obres derivades, sempre que no sigui amb finalitats comercials, i sempre que es reconegui l'autoria de l'obra original. Creative Commons
Language: Anglès.
Document: article ; recerca ; publishedVersion
Subject: Metallothionein ; Functional differentiation ; Metal specificity ; Zinc ; Copper ; Tetrahymena thermophila
Published in: International journal of biological sciences, Vol. 11 (March 2015) , p. 456-471, ISSN 1449-2288

PMID: 25798065
DOI: 10.7150/ijbs.11060


16 p, 2.2 MB

The record appears in these collections:
Articles > Research articles
Articles > Published articles

 Record created 2018-01-31, last modified 2018-11-14



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