Zinc Center as Redox Switch—New Function for an Old Motif

Oxidative stress affects a wide variety of different cellular processes. Now, an increasing number of proteins have been identified that use the presence of reactive oxygen species or alterations in the cellular thiol–disulfide state as regulators of their protein function. This review focuses on two members of this growing group of redox-regulated proteins that utilize a cysteine-containing zinc center as the redox switch: Hsp33, the first molecular chaperone, whose ability to protect cells against stress-induced protein unfolding depends on the presence of reactive oxygen species and RsrA, the first anti-sigma factor that uses a cysteine-containing zinc center to sense and respond to cellular disulfide stress.