Protocellular energy transduction, information and fitness.

An integrated protocellular system is presented and studied in simulation. In this system, co-factor molecules serve both as part of an electron relay for an energy transduction mechanism and as combinatorial molecules that can replicate. Thus, the co-factor acts as a primitive inheritable information store. This work is done to elucidate critical experimental design issues connecting energy transduction and inheritable information. Simulations are used to study how the co-factor sequence determines the protocellular 'fitness' as reflected by the calculated charge transfer and replication rates, and we compare these rates with experimentally observed production and degradation rates from similar systems. Replication and charge transport processes turn out to have different and often opposing co-factor requirements, and it turns out that we can estimate the combined fitness of the two processes. Finally, we probe the feasibility of randomly picking co-factor molecules from a limited population, where a good co-factor can enhance both metabolic biomass production and its own replication rate.This article is part of the theme issue 'Origins of life: the possible and the actual'.