Inactivation of DNA repair genes leads to the induction of vitamin B1 biosynthesis.

Extracellular oxidative stress and intracellular redox metabolism generate ROS, which can attack DNA to yield oxidatively damaged DNA. (A) In the wild-type strain, oxidatively damaged DNA is repaired by DNA repair enzymes including MutS, MutL, and MutS2. (B) In the ΔmutS, ΔmutL, and ΔmutS2 strains, the genes for vitamin B1 biosynthesis are activated to prevent the accumulation of oxidative damage in DNA via an unknown mechanism.