Kevin Schey
Last active: 3/24/2020

Diversity of metallothioneins in the American oyster, Crassostrea virginica, revealed by transcriptomic and proteomic approaches.

Jenny MJ, Ringwood AH, Schey K, Warr GW, Chapman RW
Eur J Biochem. 2004 271 (9): 1702-12

PMID: 15096209 · DOI:10.1111/j.1432-1033.2004.04071.x

Metallothioneins are typically low relative molecular mass (6000-7000), sulfhydryl-rich metal-binding proteins with characteristic repeating cysteine motifs (Cys-X-Cys or Cys-X(n)-Cys) and a prolate ellipsoid shape containing single alpha- and beta-domains. While functionally diverse, they play important roles in the homeostasis, detoxification and stress response of metals. The originally reported metallothionein of the American oyster, Crassostrea virginica showed the canonical molluscan alphabeta-domain structure. Oyster metallothioneins have been characterized as cDNA and as expressed proteins, and here it is shown that the previously reported metallothionein is a prototypical member of a subfamily (designated as CvMT-I) of alphabeta-domain metallothioneins. A second extensive subfamily of oyster metallothioneins (designated as CvMT-II) has apparently arisen from (a) a stop mutation that truncates the protein after the alpha-domain, and (b) a subsequent series of duplication and recombination events that have led to the development of metallothionein isoforms containing one to four alpha-domains and that lack a beta-domain. Analysis of metallothioneins revealed that certain CvMT-I isoforms showed preferential association either with cadmium or with copper and zinc, even after exposure to cadmium. These data extend our knowledge of the evolutionary diversification of metallothioneins, and indicate differences in metal-binding preferences between isoforms within the same family.

MeSH Terms (11)

Animals Cadmium Evolution, Molecular Exons Female Gene Expression Regulation Male Metallothionein Ostreidae Proteomics Transcription, Genetic

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