| Summary: | 碩士 === 國立中興大學 === 化學工程學系所 === 98 === The secretion of recombinant protein into the periplasm is generally accomplished via the well-studied Sec pathway, charactering of its high translocation efficiency. Nevertheless, it can only transport proteins in an unfolded state. On the contrary, a novel system, twin-arginine translocation (Tat) pathway, is been discovered recently. There are enormous interests have been attracted by the new pathway because it can secrete cofactor-containing proteins in folded state into the periplasm of Gram-negative bacteria such as Escherichia coli. However, the translocation efficiency of the Tat pathway is much lower than that via the Sec pathway. In our previous study, we have shown that the co-expression of chaperone TorD and DmsD can improve the translocation via the Tat pathway. Moreover, the enhancements are also present in the cross activity between TorD and DmsD. In light of these findings, I will elucidate the effect of TorD and DmsD co-expression on the translocation of GFP with 28 putative signal peptides. In this study, it shows that the chaperones do not absolutely enhance the efficiency; it may depend on the intrinsic translocation signal peptide itself. Furthermore, the interaction between signal peptides and chaperones would be the decisive issue in the mechanism of Tat pathway.
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