Represses the expression of most of the genes involved in oxidative stress response, such as rbr3A-rbr3B, dfx, rd, nror, fprA1 and fprA2, coding for reverse rubrerythrins, desulfoferrodoxin, rubredoxin, NADH-rubredoxin oxidoreductase (NROR), and oxygen-reducing flavoproteins, respectively. Thus, by controlling primarily oxygen and reactive oxygen species (ROS) scavenging, PerR plays an important role in the oxidative stress defense system in C.acetobutylicum, an obligate anaerobic bacterium. Probably acts as a peroxide sensor. Cells lacking this gene exhibit almost complete aerotolerance and increased H(2)O(2) resistance. Deletion of perR does not affect the intracellular level of iron but increases two-fold that of zinc. Belongs to the Fur family.