Appl Biochem Biotechnol 2016 Feb 30;178(4):710-24. Epub 2015 Oct 30.
Bioresources Technology Unit, National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency, Pathum Thani, 12120, Thailand.
The thermotolerant methylotrophic yeast Ogataea thermomethanolica is a host for heterologous protein expression via secretion to the culture medium. Efficient secretion is a major bottleneck for heterologous protein production in this strain. To improve protein secretion, we explored whether the use of a native signal peptide sequence for directing heterologous protein secretion and overexpression of native ER-resident chaperone genes could improve heterologous protein secretion in O. thermomethanolica. We cloned and characterized genes encoding α-mating factor (Otα-MF) and ER-resident chaperones OtBiP, OtCNE1, and OtPDI. The pre and pre-pro sequences of Otα-MF were shown to promote higher secretion of heterologous endoxylanase comparing with the classical pre-pro sequence of Saccharomyces cerevisiae. However, in the case of heterologous glycosylated phytase, only the Otα-MF pre-pro sequence significantly enhanced protein secretion. The effect of chaperone overexpression on heterologous protein secretion was tested in cotransformant cells of O. thermomethanolica. Overexpression of ER-resident chaperones improved protein secretion depending on heterologous protein. Overexpression of OtBiP, OtCNE1, and OtPDI significantly increased unglycosylated endoxylanase secretion at both 30 and 37 °C while only OtBiP overexpression enhanced glycosylated phytase secretion at 30 °C. These observations suggested the possibility to improve heterologous protein secretion in O. thermomethanolica.