Construction of New Ligation-Independent Cloning Vectors for the Expression and Purification of Recombinant Proteins in Silkworms Using BmNPV Bacmid System

A ligation independent cloning (LIC) system has been developed to facilitate the rapid and high-efficiency cloning of genes in a Bombyx mori expression system. This system was confirmed by the expression of human microsomal triglyceride transfer protein (hMTP) fused with EGFP in silkworm larvae and pupae. Moreover, hMTP and human protein disulfide isomerase (hPDI) genes were inserted into two LIC vectors harboring gcLINK sequences and were combined by using the LIC through gcLINK sequences. The constructed vector was incorporated into the Bombyx mori nucleopolyhedrovirus (BmNPV) bacmid, and injected into silkworm larvae. The expressed hMTP-hPDI complex was purified from the fat bodies of silkworm larvae. This LIC vector system was applied to express the E1, E2, and E3 subunits of human α-ketoglutarate dehydrogenase (KGDH) in silkworm larvae. The expressed proteins were purified easily from fat bodies using three different affinity chromatography steps. The LIC vectors constructed as described in this report allow for the rapid expression and purification of recombinant proteins or their complexes by using the BmNPV bacmid system.