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. 2024 Jun 25;25(13):6957. doi: 10.3390/ijms25136957

Figure 1.

Figure 1

Schematic representation of strategies to overcome the main bottlenecks limiting the efficient expression of a secreted protein in Bacillus subtilis. (A) At the transcriptional level, maximum expression of the gene of interest (GOI) is achieved by using strong promoters, optimized signal peptides (SPs), and gene amplification. (B) In the cytoplasm, intracellular GroE and DnaK chaperones prevent protein aggregation. (C) Membrane modification strategies to enhance protein secretion include (C.1) exploiting the Tat pathway; (C.2) overexpressing the SecYEG translocon; (C.3–C.5) optimizing signal peptide processing of signal peptidases SipT and SipS and signal peptide peptidases SppA and RasP; and (C6) cell surface engineering by constructing PssA and ClsA mutants. Lastly, (D) overexpression of extracytoplasmic PrsA aids in proper protein folding and prevents degradation. Created with BioRender.com (accessed on 2 May 2024).