Possible Emergence of Sequence Specific RNA Aminoacylation via Peptide Intermediary to Initiate Darwinian Evolution and Code through Origin of Life

Abstract

One of the most intriguing questions in biological science is how life originated on Earth. A large number of hypotheses have been proposed to explain it, each putting an emphasis on different events leading to functional translation and self-sustained system. Here, we propose a set of interactions that could have taken place in the prebiotic environment. According to our hypothesis, hybridization-induced proximity of short aminoacylated RNAs led to the synthesis of peptides of random sequence. We postulate that among these emerged a type of peptide(s) capable of stimulating the interaction between specific RNAs and specific amino acids, which we call “bridge peptide” (BP). We conclude that translation should have emerged at the same time when the standard genetic code begun to evolve due to the stabilizing effect on RNA-peptide complexes with the help of BPs. Ribosomes, ribozymes, and the enzyme-directed RNA replication could co-evolve within the same period, as logical outcome of RNA-peptide world without the need of RNA only self-sustained step.

Origin of Life: The Point of No Return

“…Since [11,13,30,46,[81][82][83][84][85][86][87][88][89][90]. In the RNA-peptide scenarios, the information is carried by RNA (or RNA-like) polymer, but the structure comes initially from peptides and later from evolved proteins.…”

“…In addition to RNA-peptide interactions, it seems that some amino acids can facilitate protocell formation due to the stabilization of fatty membranes [91]. If we accept the very first steps in the formation of Darwinian evolution in an RNA-peptide world, the translation, replication, selection of natural ribozymes, and the formation of the genetic code would necessarily follow [46,84]. In that case, the RNA-peptide world postulate that the components of Darwinian evolution-an information carrier, the rule (genetic code), and a function carrier emerged in the same set of physicochemical events as discussed above.…”

“…Usually, the main criticism of the RNA-peptide world is the lack of replication, which is indeed critical to maintaining any newly formed Darwinian complex. Without a doubt, replication is vital for life, but according to the RNA-peptide world hypothesis, self-replication is not critical [46,84]. In the RNA-peptide world, however, self-replication of RNA is not required due to the ability of a short peptide to perform primitive replication [31,84].…”

“…Without a doubt, replication is vital for life, but according to the RNA-peptide world hypothesis, self-replication is not critical [46,84]. In the RNA-peptide world, however, self-replication of RNA is not required due to the ability of a short peptide to perform primitive replication [31,84]. In fact, the issue with replication is easily solved in the RNA-peptide world, which offers the possibility for the emergence of a simple peptide capable of holding two Mg 2+ (or any suitable two-valence metal ions) at a specific distance and facilitates the beginning of enzymatic replication with a catalytic center specific for all modern DNA and RNA polymerases.…”

“…The entity that carried out the very first primitive translation event is, in fact, the first life form and we can name it "Terra Darwinia", which is the beginning of the Darwinian evolution. It would have contained few simple short RNAs sequences, with one or two meaningful nucleotides and the resulting peptide chain could have been comprised of just one or two meaningful amino acids [46,84]. RNA sequences longer than a few nucleotides and peptide chains longer than a few amino acids are not expected to emerge purely by chance, without the support of Darwinian selection.…”