What is the recipe of life? No one knows for sure how, or exactly when, (or even where, if here on Earth or elsewhere in the vast universe) a series of chemical reactions gave rise to the first forms of life. But now, joint research by the University of North Carolina and the University of Auckland has developed a new hypothesis, laying out in detail how life was cooked.
According to the article published in the journal Molecular Biology and Evolution, life and n it originated perfect symbiosis between nucleic acid (genetic instructions for all organisms) and proteins called peptides (binding of several amino acids) RNA.
And why is this conclusion groundbreaking? It contradicts the most widely accepted hypothesis by scientists; however, it is supported by robust laboratory evidence.
Until this time, most scientists agreed that life originated from nucleic acids, and that it later evolved to include proteins, which is called the RNA world hypothesis. Instead, the new hypothesis states that this ‘little protein’ (RNA peptide) was already part of the primordial broth that gave rise to life, which has been called the RNA peptide hypothesis.
“Until now, experiments were thought to be impossible to penetrate the origins of genetics,” according to one of the study’s lead authors, Dr. Charles Carter, professor of biochemistry and biophysics. “But now we have shown that the experimental results combine very well with the RNA peptide hypothesis. These experiments provide quite convincing answers to what happened at the beginning of life on Earth.”
According to the researchers, these ‘superfamilies’ of enzymes, the peptides, possess special attributes; These attributes allow them to establish a feedback system with the first genes, which would have promoted early biology and the first forms of life , until giving rise to the diversity and complexity that multicellular organisms make possible.
As Professor Carter’s laboratory tests showed, the ancestors of these peptide families would be encoded by complementary strands. An arrangement that is quite simple, with an initial code of only two amino acids. This simplicity suggests that this structure must have occurred at a very early stage in biology, at the dawn of it.
“These interdependent peptides and the nucleic acids that encode them could have mutually aided molecular self-organization despite the constant random disruptions that affect all molecular processes,” Carter explains. “We believe this is what spawned an RNA peptide world early in the history of life on Earth.”
The shortcomings of the RNA world hypothesis
The RNA world hypothesis, the most commonly accepted on biogenesis in the scientific community, brings with it certain shortcomings and unsolvable problems, which the new RNA peptide hypothesis would sweep away with a stroke of the pen. Moreover, for Professor Wills, another of the lead authors of the study, his is “a much simpler and more probable theory of the origin of life.”
The main shortcoming of the widely accepted world theory of RNA is that it remains a mystery how the building blocks of amino acids (proteins) were first assembled. It is postulated that RNA, the molecule that currently plays roles in gene coding, regulation, and expression, arose from this primordial broth of amino acids and cosmic chemicals, eventually giving rise to first short proteins called peptides, then single-celled organisms. .
But Carter and Wills argue that RNA cannot drive this process on its own , since it lacks a property they call “reflexivity.” RNA needed peptides to form the reflective feedback loop necessary to ultimately drive life forms.
Therefore, according to them, at the beginning, there were peptides …
Peter R. Wills; Charles W. Carter. ‘Insuperable problems of the genetic code initially emerging in an RNA world’. Molecular Biology and Evolution. Doi.org/10.1016/j.biosystems.2017.09.006 given
