Fig. 3
Comparison of improvement efficiency of different mini-cistron cassettes. a Schematic representation of the different mini-cistrons cassettes. PmalA is the rhFGF21′s promoter in B. subtilis, RBS, ribosome binding site. b SDS-PAGE analysis of seven recombinant strains (CIS1 (pMATEFc1), CIS2 (pMATEFc2), CIS3 (pMATEFc3), CIS4 (pMATEFc4), CIS5 (pMATEFc5), CIS6 (pMATEFc6) and CIS7 (pMATEFc7)) and their TCP expression in B. subtilis following 24 h incubation. The molecular weight of mature rhFGF21 is about 27 kDa. Column M: molecular weight marker. The strains 1A751C and 1A751F1 served as negative and positive controls. c The scatter plot of the relationship between relative expression level and the folding free energy of rhFGF21. The relative expression level of rhFGF21 was predicted using Bio-Rad Image Lab Software 5.2.1. The relative expression of the seven recombinant strains was compared with that of the strain 1A751F1 (pMATEF). The folding free energy of rhFGF21 was predicted using the mfold Web Server. d Partial views of mRNA secondary structures of the full-length transcripts corresponding to the rhFGF21 protein, predicted using the mfold Web Server. The highlighted areas are the initiation codons and RBS sequences of different strains