Glutaredoxins with iron-sulphur clusters in eukaryotes - Structure, function and impact on disease

Structural Insights into a Fusion Protein between a Glutaredoxin-like and a Ferredoxin-Disulfide Reductase Domain from an Extremophile Bacterium

“…The UV-visible absorption spectrum of the as-purified GRX protein exhibited absorption bands, with maxima at 330, 416 and 460 nm, which are typical of the presence of [2Fe-2S] clusters (Figure S1). Analytical analysis of acid-labile sulfide and iron content revealed the presence of 1.2 ± 0.1 sulfur atoms and 0.85 ± 0.04 iron atoms per monomer, which would be consistent with the presence of a [2Fe-2S] cluster in a dimer as in most Fe-S cluster containing GRXs characterized so far [18,19]. One hundred micrograms of reduced DpGRX-FDR1 were loaded on a Sephadex S75 10/300 column connected to an ÄKTA purifier system and equilibrated in 30 mM Tris-HCl pH 8.0.…”

“…According to the propensity of several mono-domain GRXs to bind this type of cluster and the known requirement for residues interspacing the CxxC motif in GRXs, this is not so surprising. Indeed, DpGRX-FDR1 possesses a CGFC signature that is extremely similar to the one present in so-called monothiol GRXs (CGFS signatures) that bind labile Fe-S clusters [18,19]. In contrast, Fe-S cluster binding was not described for MaMRX despite exhibiting a fold similar to GRXs [13].…”

Atypical Iron-Sulfur Cluster Binding, Redox Activity and Structural Properties of Chlamydomonas reinhardtii Glutaredoxin 2

“…Glutaredoxins are split into at least four classes with classes I and II being the most widespread [5]. The class II GRXs have known functions as iron-sulfur (Fe-S) cluster transfer proteins due to their capacity to bind a labile [2Fe-2S] cluster into homodimers using the cysteine residues of the typical CGFS active site signature of each monomer and of two glutathione molecules [6,7]. Some class I GRXs also have the capacity to bind Fe-S clusters using a comparable ligation mode, but a distinct mode of dimerization [8,9].…”

“…Some class I GRXs also have the capacity to bind Fe-S clusters using a comparable ligation mode, but a distinct mode of dimerization [8,9]. However, these clusters are usually more stable and the associated functions remain unclear, although it was proposed that the transition from inactive Fe-S cluster loaded forms to active apo-forms represent a regulatory mechanism in response to the presence of oxidants [7,10,11]. In apo-forms, class I GRXs catalyze the reduction of disulfides, especially those formed upon protein glutathionylation [12].…”

“…A major structural difference distinguishing class I and II GRXs is the presence of a five amino acid insertion forming a short loop just before the CxxC/S motif [7,15]. This results in differences in glutathione binding and thus in Fe-S cluster binding and stability, between members of both classes [16,17].…”