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The zn- or cu-thionein character of a metallothionein determines its metal load when synthesized in physiological (metal-unsupplemented) conditions.

Capdevila M, Palacios O, Atrian S - Bioinorg Chem Appl (2010)

Bottom Line: The present work comprises the recombinant synthesis of four metallothioneins (MTs) in metal-unsupplemented cultures and the characterization of the recovered metal complexes by means of analytical and spectrometric techniques.These four MTs exhibit distinct metal binding preferences, from a clear Cu-thionein character to a definite Zn-thionein nature, respectively.Although in all cases, the only metal ion present in the purified complexes is Zn(2+), our results highlight an inherently different behaviour of those two types of MTs, in conditions that would mimic their synthesis in physiological environments.

View Article: PubMed Central - PubMed

Affiliation: Departament de Química, Facultat de Ciències, Universitat Autònoma de Barcelona, 08193 Cerdanyola del Vallès, Barcelona, Spain. merce.capdevila@uab.cat

ABSTRACT
The present work comprises the recombinant synthesis of four metallothioneins (MTs) in metal-unsupplemented cultures and the characterization of the recovered metal complexes by means of analytical and spectrometric techniques. The four MTs are two Drosophila (MtnA and MtnB), one yeast (Crs5), and one mouse (mMT1) metallothionein isoforms. These four MTs exhibit distinct metal binding preferences, from a clear Cu-thionein character to a definite Zn-thionein nature, respectively. Although in all cases, the only metal ion present in the purified complexes is Zn(2+), our results highlight an inherently different behaviour of those two types of MTs, in conditions that would mimic their synthesis in physiological environments. Therefore, intrinsically different roles can be hypothesized for the constitutively-produced MT peptides in the absence of any metal overload, depending on their Zn- or Cu-thionein character.

No MeSH data available.


Related in: MedlinePlus

Deconvoluted ESI-TOF MS spectra of the recombinant Zn(II)-MT complexes obtained from the pGEX-MT expression system with no zinc supplementation to the culture: (a) mouse MT1; (b) yeast Crs5; (c) D. melanogaster MtnB and (d) D. melanogaster MtnA. (e) MtnB was also synthesized in zinc-enriched medium, to be used as a control.
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fig1: Deconvoluted ESI-TOF MS spectra of the recombinant Zn(II)-MT complexes obtained from the pGEX-MT expression system with no zinc supplementation to the culture: (a) mouse MT1; (b) yeast Crs5; (c) D. melanogaster MtnB and (d) D. melanogaster MtnA. (e) MtnB was also synthesized in zinc-enriched medium, to be used as a control.

Mentions: The mMT1 isoform, one of the four encoded in the mouse (mammalian) genomes, has for a long time been the paradigm of divalent-metal binding MTs. Accordingly, it is in the third position out of sixteen in our gradate classification of Zn-thioneins, as shown in Table 3. This means that the corresponding polypeptide has a high ability to form complexes with divalent metal ions (Zn2+ and Cd2+) so that these complexes are well folded and remain steady in physiological conditions. Strikingly, recombinant synthesis of mMT1 renders unique Zn7-mMT1 complexes (Figure 1(a), Table 2), regardless of whether the bacterial culture has been supplemented with zinc (300 μM) [7] or not. This suggests an extreme proficiency of mMT1 not only to form well-structured Zn-complexes when these metal ions are in surplus, but also to capture the Zn2+ ions present in a standard environment, which may be of significant importance when considering its potential functions in physiological conditions.


The zn- or cu-thionein character of a metallothionein determines its metal load when synthesized in physiological (metal-unsupplemented) conditions.

Capdevila M, Palacios O, Atrian S - Bioinorg Chem Appl (2010)

Deconvoluted ESI-TOF MS spectra of the recombinant Zn(II)-MT complexes obtained from the pGEX-MT expression system with no zinc supplementation to the culture: (a) mouse MT1; (b) yeast Crs5; (c) D. melanogaster MtnB and (d) D. melanogaster MtnA. (e) MtnB was also synthesized in zinc-enriched medium, to be used as a control.
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2864907&req=5

fig1: Deconvoluted ESI-TOF MS spectra of the recombinant Zn(II)-MT complexes obtained from the pGEX-MT expression system with no zinc supplementation to the culture: (a) mouse MT1; (b) yeast Crs5; (c) D. melanogaster MtnB and (d) D. melanogaster MtnA. (e) MtnB was also synthesized in zinc-enriched medium, to be used as a control.
Mentions: The mMT1 isoform, one of the four encoded in the mouse (mammalian) genomes, has for a long time been the paradigm of divalent-metal binding MTs. Accordingly, it is in the third position out of sixteen in our gradate classification of Zn-thioneins, as shown in Table 3. This means that the corresponding polypeptide has a high ability to form complexes with divalent metal ions (Zn2+ and Cd2+) so that these complexes are well folded and remain steady in physiological conditions. Strikingly, recombinant synthesis of mMT1 renders unique Zn7-mMT1 complexes (Figure 1(a), Table 2), regardless of whether the bacterial culture has been supplemented with zinc (300 μM) [7] or not. This suggests an extreme proficiency of mMT1 not only to form well-structured Zn-complexes when these metal ions are in surplus, but also to capture the Zn2+ ions present in a standard environment, which may be of significant importance when considering its potential functions in physiological conditions.

Bottom Line: The present work comprises the recombinant synthesis of four metallothioneins (MTs) in metal-unsupplemented cultures and the characterization of the recovered metal complexes by means of analytical and spectrometric techniques.These four MTs exhibit distinct metal binding preferences, from a clear Cu-thionein character to a definite Zn-thionein nature, respectively.Although in all cases, the only metal ion present in the purified complexes is Zn(2+), our results highlight an inherently different behaviour of those two types of MTs, in conditions that would mimic their synthesis in physiological environments.

View Article: PubMed Central - PubMed

Affiliation: Departament de Química, Facultat de Ciències, Universitat Autònoma de Barcelona, 08193 Cerdanyola del Vallès, Barcelona, Spain. merce.capdevila@uab.cat

ABSTRACT
The present work comprises the recombinant synthesis of four metallothioneins (MTs) in metal-unsupplemented cultures and the characterization of the recovered metal complexes by means of analytical and spectrometric techniques. The four MTs are two Drosophila (MtnA and MtnB), one yeast (Crs5), and one mouse (mMT1) metallothionein isoforms. These four MTs exhibit distinct metal binding preferences, from a clear Cu-thionein character to a definite Zn-thionein nature, respectively. Although in all cases, the only metal ion present in the purified complexes is Zn(2+), our results highlight an inherently different behaviour of those two types of MTs, in conditions that would mimic their synthesis in physiological environments. Therefore, intrinsically different roles can be hypothesized for the constitutively-produced MT peptides in the absence of any metal overload, depending on their Zn- or Cu-thionein character.

No MeSH data available.


Related in: MedlinePlus