Functional expression of LZ-8, a fungal immunomodulatory protein from Ganoderma lucidium in Pichia pastoris.

LZ-8, a fungal immunomodulatory protein found in Ganoderma lucidium, has been proposed to have therapeutic effects on cancer and autoimmune diseases. To develop an efficient and facile expression system supplying of rLZ-8 of high purity and stable activity for further study and applications, a full-length cDNA of lz8 gene was cloned into the pPIC9K to construct a yeast expression vector pPIC9K-lz8, then transformed to Pichia pastoris strain GS115. The molecular weight of the rLZ-8 was about 17 kDa. The yield of rLZ-8 reached up to 270 mg L(-1) at optimal culture conditions. In vitro, the rLZ-8 was capable of hemagglutinating mouse red blood cells, but no such activity was observed toward human red blood cells, which were similar to the native LZ-8. The mouse splenocyte proliferation activity of rLZ-8 expressed in P. pastoris was much higher than the rLZ-8 expressed in E. coli. All these results suggested that the active rLZ-8 protein can be expressed efficiently in the P. pastoris expression system. This report may supply a new economic and convenient way for the application of LZ-8 protein.