Proteins erylysin B (EryB) from king oyster mushroom (Pleurotus eryngii) and pleurotolysin B (PlyB) from oyster mushroom (P. ostreatus) are 59 kDa proteins belonging to MACPF protein superfamily. The combination of these proteins and an appropriate aegerolysin protein partner forms bi-component multimeric transmembrane pore in membranes with specific lipid receptors. Erylysin B and PlyB can be expressed recombinantly in bacteria Escherichia coli, but they do not fold properly and are found in inclusion bodies. Therefore, the inclusion bodies need to be isolated and the proteins refolded to gain active proteins. The goal of our research was to express soluble EryB and PlyB in the yeast Pichia pastoris in higher concentrations. We monitored the expression of recombinant proteins EryB and PlyB with several tests, including gel electrophoresis and Western blot. Erylysin B and PlyB are lytic in the presence of aegerolysin protein partner ostreolysin A6, therefore the presence of proteins in the media was tested by monitoring the hemolysis.The lysis of erythrocytes did not occur, so we concluded that the yeast P. pastoris in the combination with pGAPZαA expression vector is not a suitable expression system for the production of recombinant EryB and PlyB.
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