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Fig. 7 | Microbial Cell Factories

Fig. 7

From: Engineering the flagellar type III secretion system: improving capacity for secretion of recombinant protein

Fig. 7

Comparison of expression and secretion in secretion signal variants. a, b The ‘prototype’ E. coli ΔfliC ΔflgKL (ΔCKL) harbouring either pJex-fliC47-empty or the secretion signal variants SC0–SC9 (see Fig. 6), along with ΔflhDC and ΔfliC ΔflgKL ΔclpX (ΔCKL-X or ‘Mark II strain’) expressing SC0 were grown and harvested as in Fig. 3. a Intracellular fractions were prepared for immunoblotting (plus densitometry analysis: representative image shown), and b secreted fractions for MUB secretion assay, as described in Fig. 4a and c respectively. Three biological repeats, normalised to ΔCKL-SC0, ± SE and individual data points shown. One-way ANOVA (for SC0–SC9 expressing strains only) p < 0.001 and Tukey’s multiple comparison test (to ΔCKL-SC0): ****p < 0.001, ***p < 0.005. c The absence of the 47 residue FliC signal, with the presence of the fliC 5′UTR was investigated in ΔCKL, ΔCKL-X and ΔflhDC compared to SC1. Procedure as described for Fig. 7b. Two biological replicates, ± SE and individual data points shown

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