The production of membrane-associated lipase from Rhizopus chinensis (RCL), which has a high ester synthesis activity and important potential applications, is difficult in heterologous expression system such as Escherichia coli and often leads to the formation of inclusion bodies. Here, we describe the soluble expression of mature RCL (mRCL) using maltose-binding protein (MBP) as a solubility-enhancing tag in the E. coli system. Although the MBP-mRCL fusion protein was soluble, mRCL was insoluble after removal of the MBP tag in E. coli BL21 (DE3). Using E. coli BL21 trxB (DE3) as an expression host, soluble mRCL was obtained and expression conditions were optimized. Furthermore, the ester synthesis activity of soluble mRCL was increased by detergent treatment and was found to be 3.5 and 1.5 times higher than those of the untreated enzyme and naturally occurring enzyme, respectively. Overall, this study provides a potential approach for producing active and soluble forms of eukaryotic lipases in a heterologous E. coli expression system.
Keywords: Ester synthesis activity; Maltose-binding protein fusion tag; Membrane-associated lipase; Soluble expression.
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