Coupling information and metabolism

Two approaches to this coupling exist in theory: 1) the information molecules are the metabolic catalysts as envisioned by the RNA world and 2) the information molecule serves as an actuator for the metabolic species. Thus, it effectively controls the metabolism. This function of the information must be obtained while preserving its capacity to be replicated. This restriction drastically limits the number of candidate molecules to polymers and more specifically nucleic acid derivatives.

As stated in the information section, using nucleic acids as encoding species is precluded by the complexity of the apparatus required for their replication. A ribozyme selection for the metabolism could be possible depending on the metabolism envisioned. It might however be rather difficult depending on the envisioned metabolism.

The question then is whether a direct link between information and metabolism can be achieved directly. The additional properties of nucleic acids are known such as the possibility of shuffling of electrons and holes (lack of an electron). Thus, the control of an electron transfer reaction by nucleic acid polymers seems plausible and this approach was chosen (see metabolism). The propensity of shuttling electron will depend on the sequence of the double stranded nucleic acid. Thus, the sequence of the information polymer will determine the reaction rates or the absence of reaction.

Ruthenium complexes are presently used as “light harvesting” components of the basic FLinT-protocell metabolism. To develop their reduction potential, a compatible electron donor (oxo-Guanine) needs to be present. An oxo-G-Ru-bipyridinium conjugate might increase the efficiency of this process due to the possibility of an innermolecular electron transfer. This conjugate is also a model compound for a “gene-photosesitizer conjugate”. The synthetic steps to build up larger DNA-Ru-complex conjugates to study the sequence dependency of the redox potential are very similar. At the time Kent A. Nielsen and Mark Dörr are establishing their synthesis and other FLinT-protocell building blocks, which were developed in Los Alamos by James Bonzella, Liaohai Chen, Pierre-Alain Monnard and Mike DeClue. The following components of the envisioned FLinT-protocell scheme have been synthesized:

A Ru(bipy)-oxoG species with an aliphatic anchor chain is synthesized by Kent Nielsen. In parallel a second species without the C10- anchor is synthesized by Mark Dörr. These synthesis need nine to ten steps to come to the desired product. Completing the synthesis will open the field for many derivatives that enable the fine-tuning and study of sequence dependency and other questions related to the FlinT-protocell metabolism.