Ribocell Modeling

Extended Abstract A minimal living cell, or protocell, is a minimal supra molecular self-bounded structure that can exhibit self-maintenance, selfreproduction and evolvability (Luisi 2003). Some years ago, Szostak and colleagues proposed a minimal cell prototype called Ribocell: ribozymes based cell (Szostak et al. 2001) that, in principle, can exhibit all these three properties. This model cell consists in a self-replicating minimum genome coupled with a self-reproducing lipid vesicular container. The genome is composed by two hypothetical ribozymes: RLip able to catalyze the conversion of molecular precursors into membrane lipids and RPol able to duplicate RNA strands. Therefore, in an environment rich of both lipid precursors and activated nucleotides the Ribocell can self-reproduce if both processes: the genome self-replication and the membrane reproduction (growth and division), are somehow synchronized. In a recent work (Mavelli et al in press) we have presented and discussed a detailed and as realistic as possible kinetic mechanism for the Ribocell based on a previously published in silico model of self-replicating vesicles (Mavelli and Ruiz-Mirazo 2007):