Abstract
An RNA-lipid origin of life scenario provides a plausible route for compartmentalized replication of an informational polymer and subsequent division of the container. However, a full narrative to form such RNA protocells implies that catalytic RNA molecules, called ribozymes, can operate in the presence of self-assembled vesicles composed of prebiotically relevant constituents, such as fatty acids. Hereby, we subjected a newly engineered truncated variant of the L1 ligase ribozyme, named tL1, to various environmental conditions that may have prevailed on the early Earth with the objective to find a set of control parameters enabling both tL1-catalyzed ligation and formation of stable myristoleic acid (MA) vesicles. The separate and concurrent effects of temperature, concentrations of Mg2+, MA, polyethylene glycol and various solutes were investigated. The most favorable condition tested consists of 100 mM NaCl, 1 mM Mg2+, 5 mM MA, and 4 °C temperature, whereas the addition of Mg2+-chelating solutes, such as citrate, tRNAs, aspartic acid, and nucleoside triphosphates severely inhibits the reaction. These results further solidify the RNA-lipid world hypothesis and stress the importance of using a systems chemistry approach whereby a wide range of prebiotic factors interfacing with ribozymes are considered.
Highlights
It has been postulated that catalytic RNA molecules, called ribozymes, have served essential functions at an earlier stage [1,2], before the transition to modern biology whereby DNA is the main informational polymer and protein enzymes are the catalysts
We show that there exists a complex interplay between temperature, fatty acid concentration, and polyethylene glycol (PEG)-induced crowding, with enhancing or inhibiting effects depending on the precise conditions
(Figure 4c), which may cause RNA misfolding or hindered accessibility of the ligand binding site. These results reveal the complex interplay between the effects of temperature and Together, these results reveal the complex interplay between the effects of temperature and fatty fatty acid concentration, which leads to nonmonotonic activity profiles whose optimum is shifted to acid concentration, which leads to nonmonotonic activity profiles whose optimum is shifted to higher higher concentrations when temperature increases
Summary
It has been postulated that catalytic RNA molecules, called ribozymes, have served essential functions at an earlier stage [1,2], before the transition to modern biology whereby DNA is the main informational polymer and protein enzymes are the catalysts Even in this RNA-centric hypothesis of the origins of life, it is clear that a myriad of other compounds and factors have influenced the folding, reactivity, selection, and evolution of ribozymes [3]. Our experiments do not capture the full molecular complexity and environmental conditions on the early Earth, our findings on a new variant of the L1 RNA ligase emphasize that recapitulating in the laboratory the path from prebiotic chemistry to a ribozyme-based protocell asks for a global approach, in which RNA catalytic properties are investigated with a background of relevant compounds under various temperatures
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