Effects of Serine or Threonine in the Active Site of Typical 2-Cys Prx on Hyperoxidation Susceptibility and on Chaperone Activity.

Carlos A Tairum,Guilherme Toledo-Silva,Vitoria Isabela Montanhero Cabrera,Luis Eduardo Soares Netto,Melina Cardoso Santos,Carlos Alexandre Breyer,Marcos Antonio De Oliveira,Marcos Hikari Toyama,Ana Laura Pires De Oliveira,Gustavo Maruyama Mori

doi:10.3390/antiox10071032

Abstract

Typical 2-Cys peroxiredoxins (2-Cys Prx) are ubiquitous Cys-based peroxidases, which are stable as decamers in the reduced state, and may dissociate into dimers upon disulfide bond formation. A peroxidatic Cys (CP) takes part of a catalytic triad, together with a Thr/Ser and an Arg. Previously, we described that the presence of Ser (instead of Thr) in the active site stabilizes yeast 2-Cys Prx as decamers. Here, we compared the hyperoxidation susceptibilities of yeast 2-Cys Prx. Notably, 2-Cys Prx containing Ser (named here Ser-Prx) were more resistant to hyperoxidation than enzymes containing Thr (Thr-Prx). In silico analysis revealed that Thr-Prx are more frequent in all domains of life, while Ser-Prx are more abundant in bacteria. As yeast 2-Cys Prx, bacterial Ser-Prx are more stable as decamers than Thr-Prx. However, bacterial Ser-Prx were only slightly more resistant to hyperoxidation than Thr-Prx. Furthermore, in all cases, organic hydroperoxide inhibited more the peroxidase activities of 2-Cys Prx than hydrogen peroxide. Moreover, bacterial Ser-Prx displayed increased thermal resistance and chaperone activity, which may be related with its enhanced stability as decamers compared to Thr-Prx. Therefore, the single substitution of Thr by Ser in the catalytic triad results in profound biochemical and structural differences in 2-Cys Prx.

Highlights

Typical 2-Cys peroxiredoxins (2-Cys Prx) of the AhpC/Prx1 sub-family are peroxidases widely distributed in prokaryotes and eukaryotes that reduce hydroperoxides with high efficiency [1,2,3,4]
We show that yeast 2-Cys Prx (AhpC/Prx1 subfamily) with Ser in the catalytic triad are more resistant to hyperoxidation than those containing Thr
We investigated if the presence of Thr or Ser in the catalytic triad could affect the a small fraction of the enzyme was detected as dimers, independently of the redox state susceptibility of bacterial 2-Cys Prx to hyperoxidation

Summary

Introduction

Typical 2-Cys peroxiredoxins (2-Cys Prx) of the AhpC/Prx sub-family are peroxidases widely distributed in prokaryotes and eukaryotes that reduce hydroperoxides with high efficiency [1,2,3,4]. These enzymes are very abundant, representing 0.1–1.0% of all soluble proteins in the cells [5,6,7,8] and capable of decomposing distinct hydroperoxides [9,10]. CP is in close proximity to other two fully conserved residues (Thr/Ser and Arg), forming polar interactions that increase the electrophilicity of H2 O2 , and facilitate the nucleophilic attack by the thiolate on CP [20]

Methods

Results

Conclusion