An unexpected role for ergothioneine

Ever since the appearance of atmospheric oxygen, organisms have needed ways to protect themselves from damage caused by oxidative stress. Glutathione (GSH, Fig. 1A) is the dominant organothiol in eukarya to detoxify products formed from oxidative stress. In bacteria, several different small molecule thiols have evolved including GSH, mycothiol (MSH, Fig. 1A), a cysteinyl pseudodisaccharide found in actinomycetes, bacillithiol discovered first in bacilli and since then found in specific bacterial genera, and ergothioneine (EGT, Fig. 1A) produced by fungi and actinobacteria