ABSTRACT
All cells have to maintain their reduced state of the cytoplasm to ensure proper protein functions and cellular survival. To maintain the redox balance, eukaryotic and prokaryotic organisms utilize low-molecular-weight (LMW) thiols. LMW thiols are small thiol-containing compounds that function in the defense against reactive oxygen, chlorine, and electrophilic species (ROS, RCS, RES), antibiotics, heavy metals and other redox-active compounds (Masip et al., 2006; Van Laer et al., 2013; Chandrangsu et al., 2018). The best-studied LMW thiol is the tripeptide glutathione (GSH), which is produced in eukaryotic organisms, most Gram-negative bacteria and in some Gram-positive bacteria, including Streptococcus agalactiae, Listeria monocytogenes, and Clostridium acetobutylicum (Fahey, 2013; Loi et al., 2015). However, Gram-positive bacteria do not produce GSH and instead, utilize alternative LMW thiols. Bacillus and Staphylococcus species utilize bacillithiol (BSH), while Actinomycetes, such as Streptomycetes, Mycobacterium, and Corynebacterium species produce mycothiol (MSH) as their major LMW thiol (Newton et al., 2008; Newton et al., 2009) (Figure 20.1; see also Chapter 19).
