Tellurite-exposed Escherichia Coli Exhibits Increased Intracellular Α-ketogluta‐ Rate Tellurite-exposed Escherichia Coli Exhibits Increased Intracellular Α- Ketoglutarate 2 3

22 23 The tellurium oxyanion tellurite is toxic to most organisms because of its 24 ability to generate oxidative stress. However, the detailed mechanism(s) how this 25 toxicant interferes with cellular processes have yet to be fully understood. As part 26 of our effort to decipher the molecular interactions of tellurite with living systems, 27 we have evaluated the global metabolism of α-ketoglutarate a known anti-oxidant 28 in Escherichia coli. Tellurite-exposed cells displayed reduced activity of the KG 29 dehydrogenase complex (KGDHc), resulting in increased intracellular KG content. 30 This complex’s reduced activity seems to be due to decreased transcription in the 31 stressed cells of sucA, a gene that encodes the E1 component of KGDHc. 32 Furthermore, it was demonstrated that the increase in total reactive oxygen 33 species and superoxide observed upon tellurite exposure was more evident in wild 34 type cells than in E. coli with impaired KGDHc activity. These results indicate that 35 KG may be playing a pivotal role in combating tellurite-mediated oxidative damage. 36 37 38 39 40