© Photo: Gerald Prins
MOSCOW, June 1 – RIA Novosti . The first living cell on Earth contain not only the RNA and proteins that could exist in the hot water of the primary ocean planet, and without which the assembly of these complex molecules would be impossible, it said in an article published in the journal Proceedings of the National Academy of Sciences .
“The cooperation between RNA and peptides are likely needed for the spontaneous development of the variety of chemical complexity, which is typical for modern living world. We believe that life on the early Earth was a world of proteins and RNA, and not just the RNA world “, – said Charles Carter (Charles Carter) from the University of North Carolina at Raleigh (USA).
According to the generally accepted theory today” RNA world “, the role of proteins and DNA in the first living organisms on Earth played an RNA molecule. As a consequence of cellular processes steel control proteins, and as a repository of genetic information taken DNA. Today, scientists are experimenting with short RNA molecules, trying to reproduce the process of the origin of life in the laboratory.
The two groups of biologists from the University of North Carolina under the direction of Carter and his colleagues Volfendena Richard (Richard Wolfenden) conducted experiments in his lab, trying to understand as was made the transition from the RNA world to the “tandem” of DNA and proteins.
As the researchers explain, the problem is that the protein molecules are stable only in a very narrow range of basic chemical parameters. If at least one of them is violated, the three-dimensional protein molecules usually breaks or deforms.
This property of proteins is one of the main reasons why scientists had to come up with “RNA world” – the primary Earth’s oceans could be too warm to protein molecules therein can exist normally. Carter and Volfenden check whether it is studying the behavior of amino acids in unusual temperatures.
These experiments have led to unexpected results. It was found that the difference in the physical properties of the amino acids and the way they interact with the nucleotides and were similar at 25 degrees Celsius, the optimum temperature for life, even at 100 degrees.
This protein will ” fold “in a three-dimensional molecule by the same rules as in the warm water and in boiling water, suggesting the possibility of their existence in the hot primary ocean Earth.
Confirm that scientists have found in the transport of RNA molecules amino acids which grip and carry them to the center of the assembly of proteins in the cell. As it turned out, tRNA contain two amino acid recognition systems, one of which focuses on the size of the molecules, and the second – how well they repel water.
The first is at the “tail” tRNA for which It clings amino acid and consists of four genetic “letters”, the combination of which allows you to encode just 24 different molecular size. The second is located at the top of the tRNA, the so-called anticodon of three nucleotides, which clings to the decodable chain of genetic information.
The existence of such a double system of selection of amino acids, according to the authors, it suggests that the evolution of proteins was in two phases during the origin of life.
The first of these, they said, was completed before the advent of DNA, and while protein molecules are arranged simply – in single lines and simple two-dimensional structure. To build such structures was enough to know the dimensions of amino acids, which appear to be encoded in the RNA molecules of the body time “RNA world”. These proteins appear to have played a supporting role and help stabilize cell RNA molecules.
The emergence of a new “information carrier” – the DNA – and the related possibility to distinguish amino acids and their degree of hydrophobicity allowed to make quality of life step forward and begin to use complex three-dimensional structure of the protein, resulting in life acquired the appearance that it has today, the scientists conclude.
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