Reducing the Endogenous Protein Background of Aspergillus niger Cell Factory by RNA Interference Technology
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Abstract:
RNA interference (RNAi) technology was used to modify Aspergillus niger cell factory by reducing the expression level of its endogenous proteins. The effect of the specificity of reverse complementary sequence on RNA interference was investigated. Simultaneous interference of glucoamylase gene glaA, amylase gene amyA and protease regulator gene prtT was conducted in A. niger SH-2, and heterologous lipase tll was expressed in the RNAi-modified A. niger SH-2 host. Results illustrated that the reverse complementary sequence of different lengths exhibited RNA interference effect in different extent. RNAi vector pAMDS-RNAi-glaA388 with short reverse complementary sequence owned better interference effect (94.40%) than RNAi vector pAMDS-RNAi-glaA784 with long reverse complementary sequence (70.60%). Simultaneous interference of the three genes by pAMDS-multi-RNAi resulted in reduced expression of glaA (5.30%), amyA (17.10%) and prtT (34.60%) in A. niger SH-2. The expression of lipase tll in such RNAi-modified A. niger SH-2 reached the highest lipase activity of 97.27 U/ml, which was improved by 33.16% compared to tll expression in wild A. niger SH-2 (73.05 U/mL). Thus, RNAi technology could effectively reduce the expression background of endogenous proteins in A. niger SH-2, and could improve the expression level and stability of heterologous genes in A. niger cell factory.
