Copper metallothionein, a copper-binding protein from Neurospora crassa

Abstract

Copper is an essential constituent of many proteins which participate in biologically important reactions. In contrast to iron, where different metal storage and transport proteins have been extensively characterised, the existence of copper proteins serving such functions is still a matter of controversy. Studies on the biosynthesis of tyrosinase from Neurospora crassa with respect to the copper status of this fungus have shown that this organism accumulates copper with the concomitant synthesis of a small molecular weight copper-binding protein. This protein is now shown to have a striking sequence homology to the zinc- and cadmium-containing metallothioneins from vertebrates. Growth experiments suggest that this molecule fulfills several important physiological functions in this organism such as copper storage, copper detoxification and provision of copper for tyrosinase.

Copper‐binding proteins in ectomycorrhizal fungi

“…Values of molecular mass for nietallothioneins from Neurospora crassa (Lerch, 1980) and from Agaricus bisporus (Munger &: Lerch, 1985) were 2-2 kDa and 2 3 kDa, respectively.…”

“…Copper-binding proteins were purified by a combination of gel filtration and ion exchange ehromatography at 4 °C based on the methodology of Lerch (1980). To prevent oxidation of metallothioneins during extraction and purification, all buflFers were kept under a constant stream of nitrogen.…”

“…Three classes of metallothionein proteins are now recognized. Class I resembles the ec|uine kidney protein and has been isolated from Neurospora crassa (Lerch, 1980) and Agaricus hisporus (Munger & Lerch, 1985). Class 11 metallothioneins are present in Saccharomyces cerevisiae (Steflens, 1990); they do not share extensive sequence homology with Class I proteins.…”

“…I'hey have been widely implicated in detoxification and storage of cadmium, zinc and copper ions (Lerch, 1980;Winge & Miklossy, 1982;Kagi & Kojima, 1987). Three classes of metallothionein proteins are now recognized.…”

Synthesis of Metallothionein-like Peptides Cadystin A and B Occurring in a Fission Yeast, and Their Isomers

“…Amino acid analysis and FAB-MS of deS-cadystin A and B showed Glu (3), Ala (3), Gly (1), m/z 772 (M + 1) and Glu (2), Ala (2), Gly (1), m/ z 540 (M + 1), respectively. Therefore, the amino acid composition of cadystin A is Glu (3), Cys-SH (3), Gly (1), and that of cadystin B is Glu (2), Cys-SH (2), Gly (1). The amino acid sequence of 8 and 9 were determined as shown below based on the following studies,4) the absolute stereochemistry being all in Lconfiguration.…”