Biochemical, molecular and in silico characterization of arsenate reductase from pH, salt and arsenic tolerant Bacillus thuringiensis KPWP1

Abstract

The objective of the present study was to characterize aresenate reductase of pH, salt and arsenate tolerant Bacillus thuringiensis KPWP1, isolated from contaminated surface water. Interestingly, it was found that the arsC, arsB and arsR genes involved in arsenate tolerance are distributed in the genome of KPWP1. The inducible arsC gene was cloned, expressed and the purified ArsC protein showed profound enzyme activity with the KM and Kcat values as 25 µM and 0.00119 s− 1, respectively. In silico studies of KPWP1 ArsC revealed that in spite of 19–26% differences in gene sequences, the ArsC proteins of Bacillus thuringiensis, Bacillus subtilis and Bacillus cereus are structurally conserved and KPWP1 ArsC structure is close to nature. Docking and analysis of binding site showed that arsenate ion interacts with three cysteine residues of ArsC of KPWP1and predicts that the ArsC from B. thuringiensis reduces arsenate by using the triple Cys redox relay mechanism.