Asparaginyl-tRNA Synthetase (AsnRS) Is a Novel Vanadate Reductase from a Marine Bacterium

Increasing environmental releases of vanadium (V) by industrial plants pose significant risks of soil, water, and ecosystem contamination. Microbes reduce this toxic compound by producing a vanadate reductase enzyme that converts V 5+ to a less toxic compound, V 4+ . This study describes the cloning, expression, and characterization of an asparaginyl-tRNA synthetase (AsnRS) from the marine bacterium Shewanella sp. HU-ET00281. The Shewanella- AsnRS ( Sh- AsnRS) recombinant protein reduced V 5+ to V 4+ under ambient conditions. The K m and V max values were 8.70 mM and 4.45 mol-V 4+ /min/mol-protein respectively. Activity was enhanced by up to 75% on addition of Zn 2+ and Cu 2+ . Sh- AsnRS is a novel dual-function enzyme with AsnRS and V 5+ reductase activities that will aid bioremediation and environmental detoxification.