Oxidative stress, protein damage and repair in bacteria

Key Points Bacterial proteins can be damaged by oxidants that are present in the environment. Cys and Met residues are easily oxidized. Bacterial cells have a range of proteins that repair oxidized proteins. Thioredoxins (Trxs) and glutaredoxins (Grxs) repair oxidized cysteine residues. Methionine sulfoxide reductases (Msrs) repair oxidized methionine residues. Antioxidant defences are present in the bacterial cytoplasm and in extracytoplasmic compartments. Oxidative damage can have a devastating effect on the structure and activity of proteins, leading to cell death. This Review discusses how bacteria repair oxidized proteins and highlights the importance of these repair systems in physiology and virulence. Oxidative damage can have a devastating effect on the structure and activity of proteins, and may even lead to cell death. The sulfur-containing amino acids cysteine and methionine are particularly susceptible to reactive oxygen species (ROS) and reactive chlorine species (RCS), which can damage proteins. In this Review, we discuss our current understanding of the reducing systems that enable bacteria to repair oxidatively damaged cysteine and methionine residues in the cytoplasm and in the bacterial cell envelope. We highlight the importance of these repair systems in bacterial physiology and virulence, and we discuss several examples of proteins that become activated by oxidation and help bacteria to respond to oxidative stress.