New evidence for the origin of life

New research shows that the physical properties of amino acids, the close relationship between genetic code and protein folding may be the key factors in the evolution from building materials to organisms in the earth's native soup Image source: Gerald PRINS
At first, there were only simple chemicals They produce amino acids and eventually become the proteins necessary to create a single cell These single cells become plants and animals Recent studies have revealed how native soups produce amino acids as building materials, and there is a broad scientific consensus on the evolution from primary cells to plants and animals However, it is still a secret how these materials are initially assembled into proteins that form all cell structures Dr Richard Wolfenden and Dr Charles Carter explained the transformation from constituent materials to life about 4 billion years ago   According to Carter, Professor of Biochemistry and Biophysics, our work shows that the close relationship between the physical properties of amino acids, genetic code and protein folding may have played an important role long before the initial, large and complex molecules appeared This close interaction may be a key factor in the evolution of materials into organisms   In the corresponding papers published in proceedings of the National Academy of Sciences, their findings come to the questionable RNA world theory The theory assumes that RNA, the molecule currently playing a role in encoding, mediating and gene expression, takes itself out of the original soup of amino acids and cosmic chemicals to produce a short protein called polypeptide, which then forms a single cell organism   Wolfenden and Carter proposed that RNA does not work alone; in fact, it is more likely that RNA catalyzes the formation of polypeptides than that of polypeptides   The discovery adds a new dimension to the theory of how life evolved billions of years ago   It's called Luca
According to the scientific community, there was the last universal common ancestor (Luca) of all life on earth 3.6 billion years ago It could be a single celled organism with hundreds of genes It has a complete blueprint for DNA replication, protein synthesis and RNA translation It has all the basic components of modern organisms, such as lipids Before Luca, it was relatively easy to understand the way people thought life evolved   However, 3.6 billion years ago, there was no conclusive evidence of how Lucas formed from the boiling pot of chemicals that formed on earth, after the earth formed about 4.6 billion years ago Those chemicals react with each other to form amino acids, which are still the building blocks of proteins in human cells   We know a lot about Luca and start to understand the chemical process of producing constituent materials like amino acids, but there is still a knowledge gap between the two, which needs us to dig and fill in, Carter said We don't even know how to explore it   The research of the University of North Carolina leads the development of this field   Dr Wolfenden established the physical properties of 20 amino acids, and we found a link between these properties and the genetic code, Carter said This connection suggests that we have a second, earlier code that makes it possible to initiate a peptide RNA interaction that we can imagine is necessary to create the selection process for the first life on earth   So RNA doesn't have to create itself from native soup, Carter says On the contrary, even before the cells appear, there is more likely to be interaction between amino acids and nucleotides and lead to the co creation of proteins and RNA   From simple complexity
Proteins must fold in a specific way to function properly The first PNAs paper led by Wolfenden shows that the polarity (how they are distributed in water and oil) and size of 20 amino acids can help explain the complex process of protein folding, that is, the chain connected with amino acids arranges itself into a three-dimensional structure with specific biological functions   Wolfenden said: 'our experiments show how the polarity of amino acids changes over a wide temperature range in a way that does not disrupt the basic relationship between genetic code and protein folding This is very important for survival, because when life begins to come to earth, the temperature is very high, maybe much hotter than it is now or when plants and animals begin to appear   A series of biochemical experiments with amino acids in Wolfenden's laboratory have shown that the two properties, size and polarity of amino acids are necessary to explain the behavior of amino acids in protein folding, which also existed in the earth with higher temperature 4 billion years ago   The second PNAs paper, led by Carter, delves into how an enzyme called aminoacyl tRNA syntheses recognizes the transport of RNA or tRNA These enzymes translate the genetic code   Think of tRNA as an adapter, Carter said One end of the adapter carries a specific amino acid; the other end reads the genetic map of the amino acid in a messenger RNA Each synthetase cooperates with one of the 20 amino acids with its own adapter, so that the genetic map in messenger RNA can faithfully generate the correct protein each time   Carter's analysis shows that different ends of l-trna molecules contain independent codes or rules, which specifies which amino acid to choose One end of tRNA carrying amino acids is specially classified according to its size   The other end of the L-shaped tRNA molecule is called the anti codon It reads out codons, which are sequences of three RNA nucleotides in amino acid genetic information selected according to polarity   Wolfenden and Carter's discovery means that the physical properties of tRNA and amino acids, the relationship between their size and polarity are very important in the primitive period of the earth According to Carter's previous work on the tRNA synthetase, called urzymes, which has a very small active core, it now appears that the choice of size takes precedence over the choice based on polarity This sequential selection means that the earliest proteins do not have to fold into unique shapes, and their unique structures evolved later   Carter said: the translation of genetic code is the connection point between pre life chemistry and biology   He and Wolfenden believe that the intermediate stages of genetic coding can help solve two paradoxes: how complexity can be generated in simplicity, and how life can be divided between two very different polymers (proteins and nucleic acids)   Wolfenden points out that genetic coding develops in two successive stages, the first of which is relatively simple, which may be one of the reasons why life can rise when the earth is still very young   Early coding, which allows the earliest encoded polypeptide to bind to RNA, may provide a decisive selection advantage This primitive system then went through a natural selection process, thus starting a new and more biological evolution   Carter added: collaboration between RNA and peptides may be necessary for the spontaneous emergence of complexity In our view, this is a peptide RNA world, rather than a RNA only world (home of science, translated by Y sun)