Specificity of Human Sulfiredoxin for Reductant and Peroxiredoxin Oligomeric State

Abstract

Human peroxiredoxins (Prx) are a family of antioxidant enzymes involved in a myriad of cellular functions and diseases. During the reaction with peroxides (e.g., H2O2), the typical 2-Cys Prxs change oligomeric structure between higher order (do)decamers and disulfide-linked dimers, with the hyperoxidized inactive state (-SO2H) favoring the multimeric structure of the reduced enzyme. Here, we present a study on the structural requirements for the repair of hyperoxidized 2-Cys Prxs by human sulfiredoxin (Srx) and the relative efficacy of physiological reductants hydrogen sulfide (H2S) and glutathione (GSH) in this reaction. The crystal structure of the toroidal Prx1-Srx complex shows an extended active site interface. The loss of this interface within engineered Prx2 and Prx3 dimers yielded variants more resistant to hyperoxidation and repair by Srx. Finally, we reveal for the first time Prx isoform-dependent use of and potential cooperation between GSH and H2S in supporting Srx activity.

Selenocysteine Machinery Primarily Supports TXNRD1 and GPX4 Functions and Together They Are Functionally Linked with SCD and PRDX6

“…Interestingly, no detectable enzymatic activity for the reduction of phospholipid hydroperoxides was observed in the lungs, suggesting that the lungs of these mice did not contain GPX4 [ 25 ]. First, PRDX6 may support GPX4 function through heterodimerization (both proteins are thioredoxin-fold proteins, and dimerization, tetramerization, and dodecamerization are often observed among such proteins [ 47 , 48 , 49 , 50 , 51 , 52 ]). GPX4 is known as a monomeric glutathione peroxidase, whereas most other glutathione peroxidases are tetramers.…”

Beyond Antioxidant Activity: Redox Properties of Catechins May Affect Changes in the DNA Methylation Profile—The Example of SRXN1 Gene

“…Although GSH was reported to be involved in the regulation of several epigenetic mechanisms, it hardly influenced the DNA methylation level of any of the analyzed regions, which is in line with earlier studies reviewed by García-Giménez et al [ 41 ]. Moreover, recently endogenous reducing thiols, including GSH, have even been shown to support SRXN1-driven reactivation of PRDXs [ 42 ], which may explain why this thiol antioxidant should not be expected to downregulate SRXN1 expression.…”

Probing the mechanism of the peroxiredoxin decamer interaction with its reductase sulfiredoxin from the single molecule to the solution scale

“…1). 18,19 The specificity and completeness of the reaction between Tsa1 C P and Srx were ensured by using mutants that only retain the catalytic Cys residues, C P in Tsa1 and C84 in Srx. Reaction of Tsa1 C171A C P pre-activated by 2,2 0 -dipyridyl disulfide (2PDS) with Srx C48A C106V yielded the Tsa1 C171A -SS-Srx C48A C106V complex, referred to as Tsa1-SS-Srx, as investigated by non-reducing SDS-PAGE (Fig.…”

“…18 A similar structure was reported recently at the level of the decamer in the crystal state. 19 The Prx/Srx complex formation thus implies unfolding of the Prx C-terminal region that could also destabilize the decamer A interface, thus raising the questions whether Srx binding dissociates the decameric assembly and how the Prx C-terminal subunit flexibility impacts complex formation. However, presently, the interaction mechanism and dynamics in the solution of the Prx decamer with its partner proteins like Srx are unknown.…”