2wul

Publication Abstract from PubMed

Human glutaredoxin 5 (GLRX5) is an evolutionarily conserved thiol-disulfide oxidoreductase that has a direct role in the maintenance of normal cytosolic and mitochondrial iron homeostasis and its expression affects haem biosynthesis and erythropoiesis. We have crystallised the human GLRX5 bound to two [2Fe2S] clusters and four glutathione (GSH) molecules. The crystal structure revealed a tetrameric organisation with the [2Fe2S] clusters buried in the interior and shielded from the solvent by the conserved beta1-alpha2 loop, Phe69 and the GSH molecules. Each [2Fe2S] cluster is ligated by the N-terminal active site cysteine (Cys67) thiols contributed by two protomers and two cysteine thiols from two GSH. The two subunits coordinating the cluster are in a more extended conformation compared to FeS-bound human GLRX2 and the intersubunit interactions are more extensive and involve conserved residues among monothiol GLRXs. Gelfiltration chromatography and analytical ultracentrifugation supported a tetrameric organisation of holo GLRX5 while the apo protein is monomeric. Mass spectrometry analyses revealed glutathionylation of the cysteines in the absence of the [2Fe2S] 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 slower than GLRX2 and was active as a glutathione-dependent electron donor for mammalian ribonucleotide reductase.

The Crystal structure of human GLRX5: iron sulphur cluster coordination, tetrameric assembly and monomer activity.,Johansson C, Roos AK, Montano SJ, Sengupta R, Filippakopoulos P, Guo K, von Delft F, Holmgren A, Oppermann U, Kavanagh KL Biochem J. 2010 Oct 29. PMID:21029046^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.