Enhanced Extracellular Production of Heterologous Proteins in Bacillus subtilis by Deleting the C-terminal Region of the SecA Secretory Machinery

In this study, we examined the effects of modifying the C-terminal region of the SecA protein on the production of heterologous proteins in Bacillus subtilis. SecA was selected as a candidate among the components of the Sec system due to its ability to interact directly with both the precursors and membrane translocases. A phylogenetic comparison demonstrated that the C-terminal region is not well conserved among eubacterial SecA proteins. The deletion of the 61 amino acids at the C-terminal region led to an 83% increase in extracellular alkaliphilic Bacillus sp. thermostable alkaline cellulase (Egl-237) activity. Moreover, the productivity of human interferon alpha (hIFN-alpha 2b) was increased by 2.2-fold compared to the wild-type SecA, by deletion of these 61 amino acids. We indicated that the deletion of the C-terminal domain (CTD) of SecA enhanced the secretion of two different heterologous protein, Egl-237 and hIFN-alpha 2b. This study provides a useful method to enhance the extracellular production of heterologous proteins in B. subtilis.