Metallothioneins in metal regulation and toxicity in aquatic animals

Roesijadi, G.

doi:10.1016/0166-445x(92)90026-j

Cited by 773 publications

(415 citation statements)

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“…The functional significance of multiple forms of metallothioneins still has to be clearly defined. Some of these proteins are tissue specific and may be related to differences in metal requirements during the life cycle [14]. Some data suggest that their presence is related to various biological functions [14, 151. In any case, the data reported in this study demonstrate that some degree of polymorphisni is also present in single-cell organisms.…”

Section: Discussionmentioning

confidence: 99%

Purification and Primary Structure of Metallothioneins Induced by Cadmium in the Protists Tetrahymena Pigmentosa and Tetrahymena Pyriformis

Piccinni

Staudenmann

Albergoni

et al. 1994

European Journal of Biochemistry

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Tetrahymena pyriformis and Tetrahymena pigmentosa grown in the presence of a non-toxic dose of cadmium, accumulate the metal in the cytosol. Purification by gel-permeation, ion-exchange and reverse-phase high-performance liquid chromatography showed that the metal is bound principally to newly formed proteins with ultraviolet spectra and cysteine contents similar to those of CdZ+-metallothioneins from multicellular organisms. The isolated proteins revealed that the two species of ciliates each express two Cd2+-isothioneins. The primary structures determined by both Edman degradation and mass spectrometry revealed that the equivalent proteins from 7: pyriformis and 7: pigmentosa have identical sequences and that the two isoforms in each species differ only by the presence or absence of a lysine residue at the N-terminus. The development of automated mass spectrometric sequence analysis algorithms combined with an accurate determination of the molecular mass allowed the rapid confirmation of the sequences.The Tetrahymena metallothionein sequences are unusually long (105 and 104 amino acids) and show a unique internal homology which suggests that the proteins arose by gene duplication. The chains contain 31 cysteine residues, 15 of which are arranged in motifs characteristic of the mammalian metallothioneins ; the remaining residues show several unique repeating motifs, which could have interesting consequences for the tertiary structure of the metal-binding sites. Amino acid sequences of Tetrahymena metallothioneins have some similarity with other eukaryotic metallothioneins. A comparison on the basis of optimised FASTA scores, shows a closer relationship with horse metallothionein-1B. The first metallothionein was isolated by Margoshes andVallee in 1957 from horse kidney, as a particularly sulphurrich protein containing cadmium [l]. Subsequently, this and other closely related proteins have been shown to be widely distributed amongst prokaryotes and eukaryotes, e.g. in fungi, plants, invertebrates and vertebrates. Metallothioneins are low-molecular-mass, cysteine-rich, aromatic-lacking, metal-binding proteins that are believed to be involved in the regulation of essential trace metals, such as copper and zinc, and detoxification of these metals when present in excess, as well as non-essential metals. The preponderance of cysteine residues allows the metal ions to be bound by the formation of clusters of metal-thiolate complexes. Metallothioneins can be classified into the following three groups based on the arrangement of the cysteine residues in the primary structure: class I with a distribution like horse kidney metallothionein; class I1 with a distribution weakly related to class I; class 111, Correspondence to E. Piccinni, Dipartimento di Biologia, Via 19).Note. The novel amino acid sequence data published here have been submitted to the EMBL sequence data bank and is available under accession number P80394. The characteristic features of mammalian metallothioneins have been widely studied and many of the pr...

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Section: Discussionmentioning

confidence: 99%

Purification and Primary Structure of Metallothioneins Induced by Cadmium in the Protists Tetrahymena Pigmentosa and Tetrahymena Pyriformis

Piccinni

Staudenmann

Albergoni

et al. 1994

European Journal of Biochemistry

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“…It has been demonstrated that the incoming metals displace Zn from the pre-existing metallothioneins (Roesijadi & Fellingham 1987, Viarengo et al 1988. Moreover, it has been shown that metals such as Cd, Zn and Cu can induce metallothionein synthesis in aquatic animals (Roesijadi 1992). Thus, metallothioneins have been proposed as ind~cators of trace metal pollution (George & Olsson 1994).…”

Section: Introductionmentioning

confidence: 99%

Effects of natural factors (salinity and body weight) on cadmium, copper, zinc and metallothionein-like protein levels in resident populations of oysters Crassostrea gigas from a polluted estuary

Mouneyrac¹,

Amiard²,

Amiard‐Triquet³

1998

Mar. Ecol. Prog. Ser.

126

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The Gironde estuary has been shown to be the most Cd-contaminated area In France. Oysters Crassostrea gigas of different size classes were sampled from 3 sites between the mouth and 25 km upstream, to study the relative importance of natural and contamination factors on metal accumulation and metallothionein-like protein (MTLP) induction. The highest metal and MTLP concentrations were observed in the digestive gland. In all organs, the 3 metals were mainly cytosolic. An inverse relationship was generally observed between weight of soft tissues and metals or MTLP concentrations in the whole soft tissues, whereas the influence of weight on metal distribution among cytosolic and insoluble fractions was small. When oysters with similar weight of soft tissues were considered, no influence of salinity at different sites was found for Cu and Zn whereas the lowest soluble and insoluble Cd concentrations were observed at the mouth of the river. Salinity did not influence Cu and Zn distribution among the cytosolic or insoluble fractions whereas cytosolic Cd in gills and digestive gland (%) was higher at the mouth of the estuary than upstream. MTLP and metal concentrations were generally positively correlated except at those sites where metal concentrations were lowest. However when multiple regression analyses were performed, weight appeared also as a major or an important factor to explain vanations of MTLP levels, the prevalence of this natural factor versus contan~ination factors being different at ddferent sites. KEY WORDS. Oyster. Heavy metals. Metallothionein

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“…The presence of the regulatory sequence in the gene for MT (metal responsive element-MRE and glycocorticoid-responsive element-GRE), enables direct induction of the transcription with the participation of the metallic ions and glycocorticoid. The other factors stimulate the synthesis of MT in an indirect way (15)(16)(17). For all factors, there are differences in response depending on the kind of tissue and the kind of MT induced (18).…”

Section: Discussionmentioning

confidence: 99%