Protein expression in liposomes

Compartmentalization is one of the key steps in the evolution of cellular s tructures and, so far, only few attempts have been made to model this kind of "compartmentalized chemistry" using liposomes. The present work shows th at even such complex reactions as the ribosomal synthesis of polypeptides c an be carried out in liposomes. A method is described for incorporating int o 1-palmitoyl-2-oleoyl-sn-3-phosphocholine (POPC) liposomes the ribosomal c omplex together with the other components necessary for protein expression. Synthesis of poly(Phe) in the liposomes is monitored by trichloroacetic ac id of the C-14-labelled products. Control experiments carried out in the ab sence of one of the ribosomal subunits show by contrast no significant poly peptide expression. This methodology opens up the possibility of using lipo somes as minimal cell bioreactors with growing degree of synthetic complexi ty, which may be relevant for the field of origin of life as well as for bi otechnological applications. (C) 1999 Academic Press.