Abstract: How did molecules on the early Earth assemble into storehouses of
information (RNA) and machinery (proteins) surrounded by a membrane? The
membrane is the most readily explained component because prebiotic fatty
acids (such as decanoic acid) self-assemble in water into vesicles.
However, bare fatty acid vesicles flocculate in the presence of salt
water. Major questions in the Origins of Life field have therefore
included how the four bases and the sugar in RNA were selected from a
mixture of prebiotic compounds and how fatty acid vesicles were stabilized
against flocculation. Our group recently provided plausible answers to
these questions with our discoveries that nucleobases (as well as some,
but not all, related bases) and ribose bind to decanoic acid aggregates
[Black et al. PNAS 110, 13272 (2013)] and that this binding inhibits
flocculation of decanoic acid vesicles by salt. Our more recent results
suggest that the building blocks of proteins (amino acids) also stabilize
fatty acid membranes against salt-induced flocculation. Our results are
consistent with a scenario in which aggregates of fatty acids
self-assembled with the building blocks of RNA and of peptides on the
early Earth, and in which interactions among these components led to
stable membranes and the formation of the two biopolymers.