The metal binding abilities of Megathura crenulata metallothionein (McMT) in the frame of Gastropoda MTs

Pérez‐Rafael, Sílvia; Mezger, Andreas; Lieb, Bernhard; Dallinger, Reinhard; Capdevila, Mercè; Palacios, Òscar; Atrian, Sı́lvia

doi:10.1016/j.jinorgbio.2011.11.025

Cited by 24 publications

(15 citation statements)

References 26 publications

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“…Significantly, exposure of the Zn(II)-BfMT2 complexes to Cu(I) caused the progressive generation of a highly complex mixture of heteronuclear (Zn(II), Cu(I)) and homonuclear (Cu(I)) species, also comprising apo-BfMT2, which evolved into the major form from 18 eq Cu(I) added on. Thus, it is reasonable to assume that the failure to reach a minimally folded state when coordinating Cu(I) ions leads to complete proteolysis inside the bacteria producing cells, a phenomenon that we have reported before for the mollusc Megathura crenulata [47] and the Drosophila MtnE MT isoforms [48], although only for the attempts to synthesize them from low-aerated (i.e. high intracellular copper) Cu-enriched cultures.…”

Section: Resultsmentioning

confidence: 85%

Metal Dealing at the Origin of the Chordata Phylum: The Metallothionein System and Metal Overload Response in Amphioxus

et al. 2012

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Non-vertebrate chordates, specifically amphioxus, are considered of the utmost interest for gaining insight into the evolutionary trends, i.e. differentiation and specialization, of gene/protein systems. In this work, MTs (metallothioneins), the most important metal binding proteins, are characterized for the first time in the cephalochordate subphylum at both gene and protein level, together with the main features defining the amphioxus response to cadmium and copper overload. Two MT genes (BfMT1 and BfMT2) have been identified in a contiguous region of the genome, as well as several ARE (antioxidant response element) and MRE (metal response element) located upstream the transcribed region. Their corresponding cDNAs exhibit identical sequence in the two lancelet species (B. floridae and B. lanceolatum), BfMT2 cDNA resulting from an alternative splicing event. BfMT1 is a polyvalent metal binding peptide that coordinates any of the studied metal ions (Zn, Cd or Cu) rendering complexes stable enough to last in physiological environments, which is fully concordant with the constitutive expression of its gene, and therefore, with a metal homeostasis housekeeping role. On the contrary, BfMT2 exhibits a clear ability to coordinate Cd(II) ions, while it is absolutely unable to fold into stable Cu (I) complexes, even as mixed species. This identifies it as an essential detoxification agent, which is consequently only induced in emergency situations. The cephalochordate MTs are not directly related to vertebrate MTs, neither by gene structure, protein similarity nor metal-binding behavior of the encoded peptides. The closest relative is the echinoderm MT, which confirm proposed phylogenetic relationships between these two groups. The current findings support the existence in most organisms of two types of MTs as for their metal binding preferences, devoted to different biological functions: multivalent MTs for housekeeping roles, and specialized MTs that evolve either as Cd-thioneins or Cu-thioneins, according to the ecophysiological needs of each kind of organisms.

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Section: Resultsmentioning

confidence: 85%

Metal Dealing at the Origin of the Chordata Phylum: The Metallothionein System and Metal Overload Response in Amphioxus

et al. 2012

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“…To summarize, the two proteins share the following features: (1) They lack a clear metal-binding preference for any of the three metal ions assayed—Zn(II), Cd(II) or Cu(I). To this degree, this feature is clearly unprecedented in the world of Gastropoda MTs, even if some other MT isoforms of this sub-family are also characterized by a relatively small, but when compared to BgMT still significant, degree of metal-binding specificity [ 16 , 24 ]. (2) Consequently, the two MT variants of Biomphalaria glabrata (BgwtMT and BgKNMT) presented, in all the cases, mixtures of several differently metallated species.…”

Section: Discussionmentioning

confidence: 99%

Biomphalaria glabrata Metallothionein: Lacking Metal Specificity of the Protein and Missing Gene Upregulation Suggest Metal Sequestration by Exchange Instead of through Selective Binding

Niederwanger

Calatayud

Zerbe

et al. 2017

IJMS

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Abstract:The wild-type metallothionein (MT) of the freshwater snail Biomphalaria glabrata and a natural allelic mutant of it in which a lysine residue was replaced by an asparagine residue, were recombinantly expressed and analyzed for their metal-binding features with respect to Cd 2+ , Zn 2+ and Cu + , applying spectroscopic and mass-spectrometric methods. In addition, the upregulation of the Biomphalaria glabrata MT gene was assessed by quantitative real-time detection PCR. The two recombinant proteins revealed to be very similar in most of their metal binding features. They lacked a clear metal-binding preference for any of the three metal ions assayed-which, to this degree, is clearly unprecedented in the world of Gastropoda MTs. There were, however, slight differences in copper-binding abilities between the two allelic variants. Overall, the missing metal specificity of the two recombinant MTs goes hand in hand with lacking upregulation of the respective MT gene. This suggests that in vivo, the Biomphalaria glabrata MT may be more important for metal replacement reactions through a constitutively abundant form, rather than for metal sequestration by high binding specificity. There are indications that the MT of Biomphalaria glabrata may share its unspecific features with MTs from other freshwater snails of the Hygrophila family.

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“…On the contrary, substitutions/replacements of non-Cys aa residues while retaining the β 2 β 1 -frame have been thought as the major process for the evolutionary divergences of MTs in this primitive class Gastropoda. The Cu homeostatic requirements (thought to be mainly operated by β-domains) from the use of hemocyanin as a respiratory pigment in these gastropods, which is not present in oysters, has also been proposed as one of plausible factors responsible for the lack of divergently duplicated domains in gastropod MTs (Jenny et al 2016;Berger et al 1997;Perez-Rafael et al 2012;Perez-Rafael et al 1844). However, the present study claims that the formation of large MT with more than two domains should not be a bivalve-exclusive episode.…”

Section: Novel Evidences For Domain Duplication In Gastropod Mtsmentioning

confidence: 62%

Diversification and domain evolution of molluskan metallothioneins: a mini review

Nam

Kim

2017

Fish Aquatic Sci

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Background: Metallothionein (MT) is a multifunctional protein playing important roles in homeostatic regulation and detoxification of metals. Mollusk species have been considered as useful sentinel platforms for MT-based biomarker approaches, and they have been reported to display an extraordinary structural diversity of MT proteins. However, potential diversity of molluskan MTs has not been fully explored and recent updates have suggested the need of revision of evolutionary hypothesis for molluskan MTs.

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The metal binding abilities of Megathura crenulata metallothionein (McMT) in the frame of Gastropoda MTs

Cited by 24 publications

References 26 publications

Metal Dealing at the Origin of the Chordata Phylum: The Metallothionein System and Metal Overload Response in Amphioxus

Metal Dealing at the Origin of the Chordata Phylum: The Metallothionein System and Metal Overload Response in Amphioxus

Biomphalaria glabrata Metallothionein: Lacking Metal Specificity of the Protein and Missing Gene Upregulation Suggest Metal Sequestration by Exchange Instead of through Selective Binding

Diversification and domain evolution of molluskan metallothioneins: a mini review

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