%0 Journal Article %A Calderón, Iván L. %A Elías, Alex O. %A Fuentes, Eugenia L. %A Pradenas, Gonzalo A. %A Castro, Miguel E. %A Arenas, Felipe A. %A Pérez, José M. %A Vásquez, Claudio C. %T Tellurite-mediated disabling of [4Fe–4S] clusters of Escherichia coli dehydratases %D 2009 %J Microbiology, %V 155 %N 6 %P 1840-1846 %@ 1465-2080 %R https://doi.org/10.1099/mic.0.026260-0 %K ROS, reactive oxygen species %K ITRS, in vitro tellurite-reducing system %K TBAR, thiobarbituric acid-reactive substance %K MV, methyl viologen %K SOD, superoxide dismutase %I Microbiology Society, %X The tellurium oxyanion tellurite is toxic for most organisms and it seems to alter a number of intracellular targets. In this work the toxic effects of tellurite upon Escherichia coli [4Fe–4S] cluster-containing dehydratases was studied. Reactive oxygen species (ROS)-sensitive fumarase A (FumA) and aconitase B (AcnB) as well as ROS-resistant fumarase C (FumC) and aconitase A (AcnA) were assayed in cell-free extracts from tellurite-exposed cells in both the presence and absence of oxygen. While over 90 % of FumA and AcnB activities were lost in the presence of oxygen, no enzyme inactivation was observed in anaerobiosis. This result was not dependent upon protein biosynthesis, as determined using translation-arrested cells. Enzyme activity of purified FumA and AcnB was inhibited when exposed to an in vitro superoxide-generating, tellurite-reducing system (ITRS). No inhibitory effect was observed when tellurite was omitted from the ITRS. In vivo and in vitro reconstitution experiments with tellurite-damaged FumA and AcnB suggested that tellurite effects involve [Fe–S] cluster disabling. In fact, after exposing FumA to ITRS, released ferrous ion from the enzyme was demonstrated by spectroscopic analysis using the specific Fe2+ chelator 2,2′-bipyridyl. Subsequent spectroscopic paramagnetic resonance analysis of FumA exposed to ITRS showed the characteristic signal of an oxidatively inactivated [3Fe–4S]+ cluster. These results suggest that tellurite inactivates enzymes of this kind via a superoxide-dependent disabling of their [4Fe–4S] catalytic clusters. %U https://www.microbiologyresearch.org/content/journal/micro/10.1099/mic.0.026260-0