ABSTRACT
Bacillus and Staphylococcus species utilize bacillithiol (BSH), while Actinomycetes, such as Streptomycetes, Mycobacterium, and Corynebacterium species produce mycothiol (MSH) as their major low-molecular-weight thiol. The identification of the genes for BSH biosynthesis allowed the construction of BSH-deficient mutant strains for phenotype analysis to elucidate the functions of BSH. BSH plays an important role in detoxification of reactive oxygen species, RES, NaOCl, metal homeostasis, and antibiotics resistance. BSH-deficient mutants are sensitive to various oxidants and electrophiles, such as hypochlorous acid, diamide, H2O2, monobromobimane, and methylglyoxal. All operons for BSH biosynthesis are induced under disulfide stress, such as diamide and NaOCl stress as well as by other thiol-reactive compounds in different Firmicutes, such as B. subtilis, B. anthracis, and S. aureus. In Firmicutes, three bacilliredoxins have been identified as glutaredoxin homologs that co-occur together with the BSH biosynthesis enzymes in BSH producing bacteria as revealed in the STRING search.
