An unusual mode of iron-sulfur-cluster coordination in a teleost glutaredoxin

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• 作者：Lars Br?utigam ; Catrine Johansson ; Bastian Kubsch ; Michael A. McDonough ; Eckhard Bill ; Arne Holmgren ; Carsten Berndt
• 关键词：Grx ; glutaredoxin ; GSH ; glutathion ; GSSG ; glutathione disulphide ; HED ; hydroxyethyl disulphide ; Trx ; thioredoxin
• 刊名：Biochemical and Biophysical Research Communications
• 出版年：2013
• 出版时间：5 July, 2013
• 年：2013
• 卷：436
• 期：3
• 页码：491-496
• 全文大小：1194 K

文摘

Glutaredoxins that contain a Cys-X-X-Cys active site motif are glutathione-dependent thiol-disulfide oxidoreductases. Vertebrate glutaredoxin 2 is characterized by two extra cysteines that form an intra-molecular disulfide bridge. Zebrafish glutaredoxin 2 contains four additional cysteines that are conserved within the infraclass of bony fish (teleosts). Here, we present a biochemical and biophysical characterization of zebrafish glutaredoxin 2, focusing on iron-sulfur-cluster coordination. The coordination of [2Fe2S]²⁺-clusters in monomers of this protein was revealed by both absorption and M?ssbauer spectroscopy as well as size exclusion chromatography. All other holo-glutaredoxins represent [FeS]-cluster bridged dimers using two molecules of non-covalently bound glutathione and the N-terminal active site cysteines as ligands. These cysteine residues were not required for [FeS]-cluster coordination in zebrafish glutaredoxin 2. A crystal structure of the teleost protein revealed high structural similarity to its human homologue. The two vertebrate-specific cysteines as well as two of the teleost-specific cysteines are positioned within a radius of 7 ? near the C-terminus suggesting a potential role in [FeS]-cluster coordination. Indeed, mutated proteins lacking these teleost-specific cysteines lost the ability to bind the cofactor. Hence, the apparent mode of [FeS]-cluster coordination in zebrafish glutaredoxin 2 could be different from all yet described [FeS]-glutaredoxins.