Reconciling ligase ribozyme activity with Fatty Acid vesicle stability

The RNA world hypothesis suggests RNA molecules could have acted as both catalysts and genetic material before DNA and proteins evolved. The lipid world hypothesis proposes fatty acid vesicles could have formed primitive cell membranes. These two models face a challenge because RNA ligase activity and fatty acid vesicle stability require different concentrations of Mg2+. Prior research has shown that high Mg2+ is needed for ribozyme activity but weakens vesicle membranes. No prior work had resolved how these systems could coexist. This gap motivated researchers to test if a specific ribozyme could function alongside fatty acid vesicles under shared Mg2+ conditions. Existing studies suggest RNA is vulnerable to cleavage in high Mg2+ environments. That uncertainty drove experiments to measure RNA ligation rates and vesicle stability together. The study aimed to identify if a balance exists where both systems remain functional. Previous findings lacked direct evidence of coexistence. This paper addresses that limitation.

This study aimed to test the compatibility of a ligase ribozyme and fatty acid vesicles under shared Mg2+ conditions. The researchers focused on a short L1 ligase ribozyme and myristoleic acid (MA) vesicles. They wanted to determine if these two systems could coexist in the same environment. The problem arises because Mg2+ is essential for ribozyme activity but destabilizes fatty acid membranes. The motivation was to find a concentration of Mg2+ where both systems function. The study sought to measure ligation rates and vesicle stability simultaneously. The goal was to identify if a stable RNA-lipid system is possible. The researchers hypothesized that RNA might remain intact despite lower ligation rates. The findings could help reconcile the RNA and lipid world theories.

The researchers used a L1 ligase ribozyme and myristoleic acid (MA) vesicles. They tested the ribozyme activity at different Mg2+ concentrations. RNA ligation assays were conducted alongside vesicle stability measurements. The experiments involved measuring ligation rates and RNA integrity over time. They varied Mg2+ concentrations from low to high levels. The team used 5 mM MA amphiphile to form vesicles. They monitored RNA strand cleavage and ligation outcomes. The study combined biochemical assays with membrane stability analysis.

The ligation rate of the L1 ribozyme was significantly lower at low Mg2+ concentrations. However, RNA integrity was higher under those conditions. At approximately 2 mM Mg2+, both ligation and vesicle stability were maintained. MA vesicles made of 5 mM amphiphile remained stable in this Mg2+ range. The ribozyme activity was not impaired by the presence of vesicles. RNA cleavage was reduced at lower Mg2+ levels. The study found that RNA could remain intact despite reduced ligation rates. These results suggest a possible coexistence of RNA and fatty acid membranes.

The authors suggest that RNA and fatty acid vesicles can coexist under specific Mg2+ conditions. They propose that RNA stability may offset reduced ligation rates. The findings support a scenario where both systems function together. The study does not claim RNA and membranes are essential to each other. The results do not suggest fatty acids are necessary for ribozyme activity. The authors state that Mg2+ levels can balance both systems. The study does not generalize to all ribozymes or membranes. The findings align with the possibility of a shared prebiotic environment.