Nascent MSKIK peptide prevents or releases translation arrest in Escherichia coli

The insertion of the sequence encoding SKIK peptide adjacent to the M start codon of a difficult-to-express protein enhances protein production in Escherichia coli. In this report, we show that the increased production of the SKIK-tagged protein is not due to codon usage of the SKIK sequence. In addition, insertion of SKX, KKX, and AKX (X = G, L, H, Y, E, and F) at the N-terminus increased protein production. Furthermore, insertion of MSKIK just before the SecM arrest peptide (FSTPVWISQAQGIRAGP), which causes translational stalling on mRNA, greatly increased the production of the protein containing the SecM arrest peptide in the E. coli reconstituted cell-free protein synthesis system (PURE system). A similar phenomenon was observed for CmlA leader whose arrest is induced by chloramphenicol. These results suggest that the nascent MSKIK peptide prevents or releases translational stalling immediately following its generation during the translation process.