期刊
BIOCHEMICAL JOURNAL
卷 433, 期 -, 页码 303-311出版社
PORTLAND PRESS LTD
DOI: 10.1042/BJ20101286
关键词
analytical ultracentrifugation; crystallization; glutaredoxin; glutathione; iron-sulfur; ribonucleotide reductase
资金
- Swedish Research Council [3529]
- Swedish Cancer Society [961]
- Wallenberg Foundation [2006-0192]
- Wenner-Gren postdoctoral fellowship
- Canadian Institutes for Health Research [1097737]
- Canadian Foundation for Innovation, Genome Canada through the Ontario Genomics Institute
- GlaxoSmithKline
- Karolinska Institutet
- Knut and Alice Wallenberg Foundation
- Ontario Innovation Trust
- Ontario Ministry for Research and Innovation
- Merck and Co.
- Novartis Research Foundation
- Swedish Agency for Innovation Systems
- Swedish Foundation for Strategic Research
- Wellcome Trust
- Oxford NIHR Biomedical Research Unit
Human GLRX5 (glutaredoxin 5) is an evolutionarily conserved thiol-disulfide oxidoreductase that has a direct role in the maintenance of normal cytosolic and mitochondrial iron homoeostasis, and its expression affects haem biosynthesis and erythropoiesis. We have crystallized the human GLRX5 bound to two [2Fe-2S] clusters and four GSH molecules. The crystal structure revealed a tetrameric organization with the [2Fe-2S] clusters buried in the interior and shielded from the solvent by the conserved beta 1-alpha 2 loop, Phe(69) and the GSH molecules. Each [2Fe-2S] cluster is ligated by the N-terminal active-site cysteine (Cys(67)) thiols contributed by two protomers and two cysteine thiols from two GSH. The two subunits co-ordinating the cluster are in a more extended conformation compared with iron-sulfur-bound human GLRX2, and the intersubunit interactions are more extensive and involve conserved residues among monothiol GLRXs. Gel-filtration chromatography and analytical ultracentrifugation support a tetrameric organization of holo-GLRX5, whereas the apoprotein is monomeric. MS analyses revealed glutathionylation of the cysteine residues in the absence of the [2Fe-2S] cluster, which would protect them from further oxidation and possibly facilitate cluster transfer/acceptance. Apo-GLRX5 reduced glutathione mixed disulfides with a rate 100 times lower than did GLRX2 and was active as a glutathione-dependent electron donor for mammalian ribonucleotide reductase.
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