Cyanobacterial peroxiredoxins and their role in cyanobacterial stress biology

Abstract

Peroxiredoxins (Prxs), a type of enzymatic antioxidants, are central elements of the defense system. It is a dithiol–disulfide redox regulatory network for all living life-forms. Prxs utilize a thiol-based catalytic mechanism to detoxify the ROS (reactive oxygen species), RNS (reactive nitrogen species), and RSS (reactive sulfur species) such as hydrogen peroxide, alkyl hydroperoxides, and peroxynitrite. In blue-green algae (cyanobacteria), Prxs exist in 2-Cys Prx, 1-Cys Prx, PrxQ, and type II Prx forms. The catalytic cycle of peroxiredoxin consists of three steps: (1) peroxidative reduction, (2) resolving step, and (3) reduction by using various electron donors such as ascorbic acid, thioredoxins, cyclophilins, glutathione, and glutaredoxins depending upon the organisms and types of Prxs. Prx proteins of cyanobacterium undergo conformational changes independent of their redox state. Prxs not only alter cellular ROS and RNS-dependent signaling, but depending on the Prx type, they also sense the redox state and transmit redox information to binding partners, and function as a chaperone. They serve in the context of photosynthesis and respiration, but also in metabolism and development. This chapter surveys the current literature and attempts a mostly comprehensive coverage of present-day knowledge as well as concepts on the mechanism, regulation, and function of Prx and thus on the whole Prx systems in cyanobacteria. © 2020 Elsevier Inc. All rights reserved.