Overall Protocell Design

The design principle behind our protocell is simple (Rasmussen et al., 2003): Minimize the number and complexity of the physicochemical structures for the required cooperative functionalities and make sure that all structures mutually support each other. The minimal
protocell we seek to implement consists of a particular coupling between the three central components: the genetic material (information), a metabolic system (energy transduction), and a container. Because simplicity is our main goal, we are not restricted to contemporary cellular structures or building blocks. Two ideas have been important to the design:

(1) We have simplified the notion of a container by allowing the metabolic and genetic complexes to operate at the external interface of a (fatty acid) lipid or (oil) droplet aggregate, our within reverse micelles. The information incorporate amphiphilic genes, currently modified DNA with hydrocarbon tails (previously backbone modified peptide nucleic acid (PNA)). the metabolic molecules are hydrophobic photo-sensitizers, organo-metallic (Ru-bpy) structures with hydrocarbon tails (previously also organic dyes (stilbene)). All of these protocell components are designed to self-assemble in water.

(2) We have simplified the cooperativity between genetics, metabolics, and container by integrating genes as a functional component of a charge transfer process (electron donor) of the metabolism, which means that the informational molecule directly catalyze the metabolic process. The metabolism produces the container components (as well as the other building blocks), which in turn self-assemble into an aggregate, which in turn contains the metabolism and the genes as well as catalyze the gene self-replication and the metabolic processes.

 

Accepting the above design concepts allow us to explore protocells which are functionally much simpler than modern biological cells and containers as small as a few nanometers in diameter and thus orders of magnitude smaller than contemporary cells.

Reference

DeClue, M., et al., JACS 131 (2009) 931

Fellermann, H., et al., Artificial Life 13 (2007) 319

Maurer, S., et al., (2011) Chem Phys Chem 12 (2011) 828

Rasmussen, S., et al., Artificial Life 9 (2003) 269

Rasmussen, S., et al., in "Protocells: Bridging nonliving and living matter", p 125-155, Rasmussen, S., et al., eds, Cambridge MIT Press 2009

Rouchelau, T., et al., Phil. Trans. R. Soc B 362 (2007) 1841