Enhanced soluble expression of glutathione S-transferase Mu from Rutilus kutum by co-expression with Hsp70 and introducing a novel inhibitor for its activity

Abstract

One of the most critical challenges in recombinant protein production is the increment of protein solubility. The overexpression of glutathione S-transferases (GSTs) in cancers leads to the fast detoxification of drug substrates that is subsequently followed by increased drug resistance. In this study, the co-expression of Rutilus kutum Hsp70 (RkHsp70) with the mu-class GST (RkGST-μ) from the same source was analyzed to increase the solubility of aggregate-prone RkGST-μ. Based on the results, the co-expressed RkGST-μ cells showed substantially higher solubility and specific activity compared to control. The kinetic properties of the enzyme were measured and its optimum pH and temperature were observed at pH 8 and 35 °C. Furthermore, this study introduces ZM-093, a sulfamethoxazole-based azo with IC50 values of 24.45 μM (p < 0.0001), as a novel RkGST-μ inhibitor. Overall, the present study provides clear findings in support of using molecular chaperones to enhance the solubility of recombinant proteins.