Ros reactive oxygen11/16/2023 ![]() Yeast H 2O 2 homeostatic pathways use redox relays that comprise a thiol peroxidase as the H 2O 2 receptor that oxidizes a transcription factor: Yap1 in Saccharomyces cerevisiae and Pap1 in Schizosaccharomyces pombe. Inactivation by overoxidation and reactivation by sulphiredoxin regulate peroxiredoxin antioxidant functions, H 2O 2 receptor functions and redox transduction functions. Thiol-based peroxiredoxins and GPX-like peroxidases carry H 2O 2 receptors and have redox transducing functions. Their sensitivity is much lower than that of the ROS receptors. The Hsp33 chaperone and RsrA anti-sigma factor use a Cys–zinc redox centre to respond to a combination of H 2O 2 and heat (Hsp33) and to diamide (RsrA). The subcellular colocalization of ROS and their targets contributes to mammalian ROS signalling specificity.Īmong prokaryotic -cluster-based sensors, SoxR is O 2 −-specific both FNR (which senses oxygen) and IscR (which senses -cluster biosynthesis status) also respond to H 2O 2 and O 2 −.Īmong prokaryotic peroxide sensors, OxyR and OhrR use a reactive Cys residue that oxidizes to a disulphide bond, and PerR uses a non-haem iron centre, the two coordinating His residues of which oxidize to 2-oxo-His. is indiscriminate the superoxide anion O 2 − is active towards iron–sulphur () clusters and hydrogen peroxide (H 2O 2) targets reactive Cys residues.ROS chemistry dictates reactivity towards selective atomic targets in proteins. Because of the high sensitivity of these pathways, sensors can be equated to receptors and ROS signals can be equated to agonists. They use redox sensors that 'measure' ROS concentration and proportionally set the expression of ROS scavengers. Reactive oxygen species (ROS) homeostatic pathways in microbes operate instant and feedback-regulated adjustments of intracellular ROS concentration. ![]()
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