Biology subjects

Leiskau, L.

Publications and source records attributed to Leiskau, L..

3 recordsLinked to original sources

bioRxiv2026

Glutaredoxins rapidly reduce glutathione hydroper- and polysulfides

Hydropersulfides have gained attention in cell biology as excellent nucleophiles and membrane-protective radical scavengers. They form perthiyl radicals, which terminate radical chain reactions through self-recombination, leading to the formation of polysulfides. It is currently unknown how polysulfides are subsequently reduced again in non-enzymatic or enzymatic metabolic pathways. Here we used stopped-flow kinetic measurements in combination with mass spectrometry to show that the model class I glutaredoxin from the malaria parasite Plasmodium falciparum (PfGrx) rapidly reduces the polysulfides glutathione trisulfide (GS3G) and glutathione tetrasulfide (GS4G), yielding the glutathionylated enzyme and the corresponding glutathione hydropersulfide GSSH and hydrotrisulfide GS3H. The second-order rate constants of these enzymatic reductions [≥]107 M-1s-1 are even slightly higher than for glutathione disulfide (GSSG). In contrast, PfGrx was inactive or only moderately active using cystine or cysteine trisulfide as oxi-dants. GSSH and GS3H are further reduced by PfGrx with second-order rate constants on the order of 106-107 M-1s-1, yielding the glutathionylated enzyme as well as hydrogen sulfide (H2S) and hydrogen disulfide (H2S2), respectively. Thus, glutaredoxins specifically recognize the glutathione moiety of glutathione (hydro)polysulfides and glutathione hydropersulfide. Due to the rapid reduction of glutathionylated glutaredoxins by reduced glutathione (GSH), glutathione (hydro)per/polysulfides are efficiently converted to GSSG and H2S or the corresponding hydrogen polysulfides. As a consequence, the steady-state concentration of glutathione (hydro)per/polysulfides should be tightly controlled in subcellular compartments containing active glutaredoxins and high GSH concentrations.

biochemistry↗

bioRxiv2025

H2S is a potential universal reducing agent for Prx6-type peroxiredoxins

The absence of a universal reducing agent distinguishes the Prx6-type subfamily of peroxiredoxins from the structurally similar Prx1-type subfamily. A likely explanation for the lack of reactivity of Prx6-type enzymes with common reducing agents is that a Prx6-specific histidyl residue at the bottom of the active-site pocket traps the oxidized enzyme with a potentially hypervalent cysteinyl sulfur atom in an inaccessible fully-folded protein conformation. Here, we analyzed the reduction of oxidized PfPrx6 from the human malaria parasite Plasmodium falciparum and human PrxVI by the hydrosulfide ion, HS-, as the smallest possible sulfur-containing universal electron donor using stopped-flow kinetic measurements. We show that HS- rapidly reacts with oxidized wild-type PfPrx6 or human PrxVI (but not the histidyl mutant PfPrx6H39Y) with a second-order rate constant of >108 M-1s-1 at pH 7.4. The potential protein-persulfide species of PfPrx6 is neither reduced by thioredoxin nor glutaredoxin and glutathione, but further reacts with an excess of HS- with a second-order rate constant of 6.3x103 M-1s-1, yielding the reduced enzyme. In summary, we identified HS- as a highly reactive, potential universal electron donor for Prx6-type enzymes in eukaryotes, bacteria, and archaea. Our study marks the starting point for the characterization of the complex reduction pathway of Prx6-type enzymes with potential implications for H2S detoxification, redox signaling, and iron-sulfur metabolism.

biochemistry↗

bioRxiv2023

Cytosolic iron-sulfur protein assembly system identifies clients by a C-terminal tripeptide

The eukaryotic cytosolic Fe-S protein assembly (CIA) machinery inserts iron-sulfur (Fe-S) clusters into cytosolic and nuclear proteins. In the final maturation step, the Fe-S cluster is transferred to the apo-proteins by the CIA-targeting complex (CTC). However, the molecular recognition determinants of client proteins are unknown. We show that a conserved [LIM]-[DES]-[WF]-COO- tripeptide present at the C-terminus of clients is necessary and sufficient for binding to the CTC in vitro and directing Fe-S cluster delivery in vivo. Remarkably, fusion of this TCR (target complex recognition) signal enables engineering of cluster maturation on a non-native protein via recruitment of the CIA machinery. Our study significantly advances our understanding of Fe-S protein maturation and paves the way for bioengineering applications. One-Sentence SummaryA C-terminal tripeptide guides eukaryotic iron-sulfur cluster insertion into cytosolic and nuclear proteins.

biochemistry↗