The Central Role of Redox-Regulated Switch Proteins in Bacteria

Abstract

Bacteria possess the ability to adapt to changing environments. To enable this, cells use reversible post-translational modifications on key proteins to modulate their behavior, metabolism, defense mechanisms and adaptation of bacteria to stress. In this review, we focus on bacterial protein switches that are activated during exposure to oxidative stress. Such protein switches are triggered by either exogenous reactive oxygen species (ROS) or endogenous ROS generated as by-products of the aerobic lifestyle. Both thiol switches and metal centers have been shown to be the primary targets of ROS. Cells take advantage of such reactivity to use these reactive sites as redox sensors to detect and combat oxidative stress conditions. This in turn may induce expression of genes involved in antioxidant strategies and thus protect the proteome against stress conditions. We further describe the well-characterized mechanism of selected proteins that are regulated by redox switches. We highlight the diversity of mechanisms and functions (as well as common features) across different switches, while also presenting integrative methodologies used in discovering new members of this family. Finally, we point to future challenges in this field, both in uncovering new types of switches, as well as defining novel additional functions.

Rice receptor kinase FLR7 regulates rhizosphere oxygen levels and enriches the dominant Anaeromyxobacter that improves submergence tolerance in rice

“…Since FLR7 affects rhizosphere oxygen levels, we further analyzed genes related to aerobic and anaerobic respiration. The results indicated that the relative abundances of five representative aerobic respiration-related genes, cyc (expressing cytochrome c), ccmA (expressing heme exporter protein A), oxyR (expressing hydrogen peroxide-inducible gene activator), ahpC (expressing peroxiredoxin), and sod2 (expressing superoxide dismutase 2) [ 39 ], were significantly increased, while the relative abundances of two representative anaerobic respiration-related genes, nrfA (expressing nitrite reductase) and adh (expressing alcohol dehydrogenase) [ 40 ], were significantly decreased in the flr7 root microbiome compared to the Nip root microbiome ( Fig. 3B ; Table S4 ).…”

“…3C ). Aerobic respiration is accompanied by antioxidant reactions that exist in aerobic bacteria but not in anaerobic bacteria [ 39 ]. GO function analysis showed that the relative abundances of multiple antioxidant-related functions were significantly elevated in the mutant root microbiome ( Fig.…”

Streptococcus pyogenes Hijacks Host Glutathione for Growth and Innate Immune Evasion

“…In GAS, the quorum-sensing transcriptional regulator of the speB - prsA operon, RopB/Rgg, is unusually rich (a total of 10) in cysteine residues. Some of these cysteine residues are critical for RopB/Rgg activity and could thus serve as redox switches in oxidative stress sensing to regulate speB expression levels ( 66 – 69 ), providing a possible explanation for strongly repressed speB promoter activities in the HKU16Δ gshT mutant ( Fig. 3b ).…”

Reactive Oxygen Species Signaling Differentially Controls Wound Healing and Regeneration

“…Responses to ROS evolutionarily range from the activation of transcription factors in prokaryotes to promoting cellular responses (such as cell migration and proliferation) in humans 22,23 . Even cellular outcomes within the same organism can vary depending on ROS levels.…”