Development of a Hyper-Protein Secretion System via a Tat-Dependent Signal Peptide Using Streptomyces lividans

摘要

The secretion of valuable proteins is an effective way to avoid complex purification procedures, including protein refolding and extraction from cells. In this study, we focused on Streptomyces lividans as a host strain to secrete useful proteins, and screened for signal peptides from the biomass-degradation enzymes derived from Thermobifida fusca YX and S. lividans. Three candidate signal peptides were isolated and evaluated for their protein secretion ability using beta-glucosidase derived from T. fusca YX, which is a non-secreted protein, as a model protein. Using S. lividans xylanase C signal peptide, the amount of produced the beta-glucosidase reached 10 times as much as that when using Streptomyces cinnamoneus phospholipase D signal peptide, which was identified as a versatile signal peptide in our previous report. In addition, the introduction of the beta-glucosidase fused to xylanase C signal peptide using two kinds of plasmid, pUC702 and pTYM18, led to further protein secretion, and the maximal level of produced the beta-glucosidase increased up to 17 times (1.1 g/l) compared to using only pUC702 carrying the beta-glucosidase fused to S. cinnamoneus phospholipase D signal peptide. The hyper-secretion system developed here can be used to produce many types of useful proteins.