Figure 5.

Removal of the twin-arginine motif in the signal peptide blocks turnover of the NrfC M1/M2 mutants. The twin-arginine motifs in the pre-NrfC, M1 and M2 signal peptides were substituted by twin-lysine by site-specific mutagenesis, and the constructs were expressed and analysed exactly as shown in Figure 3, with time points shown after induction with arabinose. The M2 construct containing an intact signal peptide was also expressed for reference purposes (as shown in Figure 3). Total cell samples were analysed and the mobilities of the precursor proteins are shown.