A mistake in the basis of modern molecular biology found?


Scientists have found that the triad of "DNA — RNA — protein", the cornerstone of modern ideas about cells, interacts not in a way, which scientists believed for the last 50 years. Employees of the Institute of Biochemistry of the Russian Academy of Sciences and the FNSC of Physical and Chemical Medicine of the FMBA of Russia found that alternative splicing of matrix RNAs makes significantly smaller contribution to the variety of proteins within the cell.

The basis of modern ideas about how cells function is the so-called main dogma of molecular biology. It is a set of principles formulated by Francis Crick in 1970, the discoverer of DNA. He described the direction in which genetic information can move within living organisms. According to Crick's ideas, the transmission of information in biological systems is universal and one-sided: the DNA of all living organisms controls the shape of proteins and RNA, but not vice versa, and proteins cannot change the structure of RNA and DNA, and RNA can control the shape of proteins, but not DNA. There are small exceptions related to viruses, but viruses are not formally living organisms, and therefore the theory does not apply to them.

Later, scientists discovered that dogma works in a more complicated way in human cells and other multicellular creatures - our genes can contain "instructions" for the synthesis of not one but several protein molecules. Nuclear (eukaryotic) RNA molecules can undergo alternative splicing - the formation of several matrix RNAs from one that can be translated into different proteins - isoforms. Thus, it was previously assumed that one gene (a section of DNA), due to splicing, produces several RNAs that form a variety of proteins.

According to the authors, initially the team tried to understand what functions alternative versions of proteins can perform, the assembly instructions for which are in the moss genes. To do this, they exposed it to various stress factors - lack of water, light and nutrients. Soon it became clear that alternative splicing influenced the behavior of cells not as much as in theory, and the protein content of the cell depended on changes in the structure of RNA weaker than scientists expected. Accordingly, it can be said that the chain "DNA-RNA-protein" was broken: changes in the structure of its first two links did not affect the work of the latter.

In order to support their discovery scientists built a computer model of the experiment and proved that the cells had to contain dozens of times more "versions" of proteins if the alternative splicing worked. A large variety of RNA leads to very small changes in proteins, therefore, according to the authors of the study, the canonical scheme of molecular biology "from DNA to protein" is violated.

Now molecular biologists have to understand what kind of biological function is performed by alternative splicing, what is the role of interactions between RNA molecules in this process and how all this affects the appearance of new protein molecules in the cell.


Last Modified: 2017/08/11