Protein Engineering via Over-Expression in Plant Plastids
My laboratory has a long-standing interest in the mechanism of protein targeting and assembly in the plastids (chloroplasts) of plants. A number of soluble proteins have been successfully expressed in chloroplasts (e.g. IgG and insulin) and are currently being commercially produced (Grevich and Daniell, 2005). Our particular interest is to take advantage of the chloroplast system for the production of foreign membrane proteins. To this end, we are investigating the mechanism by which chloroplast membrane proteins are targeted into the organelle and inserted into the chloroplast inner envelope membrane. We have defined the pathway for this targeting and insertion process using model membrane proteins (Li and Schnell, 2006) and are currently using our knowledge of the signals that direct membrane protein targeting to engineer foreign accumulation in chloroplasts. The production of recombinant membrane proteins of biomedical relevance is of major interest to the biotechnology community. For example, the membrane receptor protein kinases (e.g. EGF-, PDGF-,NGF-, CFS-, IGF-1 and insulin receptor) play central roles in signal transduction pathways that control cell proliferation, differentiation, metabolism and apoptosis. The ability to produce chemical quantities of these proteins would greatly aid in the study, diagnosis and treatment of numerous diseases associated with these cell signaling mediators. |
