Identification of a TeO32- reductase/mycothione reductase from Rhodococcus erythropolis PR4.

Zachary J Butz, Alexander Hendricks, Kanda Borgognoni, Christopher J Ackerson

FEMS microbiology ecology 2020 Dec 29

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A Rhodococcus erythropolis bacterium that tolerates normally lethal concentrations of Fe(II), Cu(II), AsO32-, SeO32-, TeO32-, Cd(II) and Zn(II) was identified from an environmental isolate. In characterizing the molecular basis for metal tolerance, a mycothione reductase (Mtr) with remarkable selectivity for TeO32- reduction over SeO32- was identified. In equimolar concentrations of TeO32- and SeO32-, the enzymatic product contains a 7-fold excess of Te. This selectivity is remarkable because the standard reduction potential of SeO32- is 0.20 V more favorable for reduction than TeO32. Selectivity of the enzyme for TeO32- decreases with increasing assay pH. Homology modeling of the enzyme identifies four aromatic residues near the active site, including two histidine residues, that are not present in a related SeO32- preferring reductase. On the basis of more favorable π-interactions for Te than for Se and the pH dependence of the selectivity, the Te-selectivity is attributed in part to these aromatic residues. The resulting Te0 enzymatic product resembles Te nanowires. © The Author(s) 2020. Published by Oxford University Press on behalf of FEMS.

Citation

Zachary J Butz, Alexander Hendricks, Kanda Borgognoni, Christopher J Ackerson. Identification of a TeO32- reductase/mycothione reductase from Rhodococcus erythropolis PR4. FEMS microbiology ecology. 2020 Dec 29;97(1)