Russian biologists have discovered that the DNA-RNA-protein triad, the cornerstone of the current understanding of the work of cells, interacts differently than scientists believed the last 50 years, according to an article published in the journal Scientific Reports.
“When scientists found that eukaryotic genes could be subjected to alternative splicing, it was suggested that the gene could encode a huge number of different proteins through this process, in part this is true: in any organism, there are genes that code for a variety of different protein isoforms, That on the whole this is not so, “says Igor Fesenko from the Institute of Bioorganic Chemistry of the Russian Academy of Sciences in Moscow.
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, the discoverer of DNA, in 1970 to describe the direction in which genetic information can move within living organisms.
According to Crick’s ideas, the transfer 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 can not change the structure of RNA and DNA, and RNA can control the shape of proteins, but not DNA. There are small exceptions associated with viruses, but viruses are not formally living organisms, and therefore dogma is not fulfilled for them.
Subsequently, scientists found that dogma works somewhat more difficult for human cells and other multicellular creatures – our genes can contain “instructions” for the synthesis of not one but several protein molecules. When the nucleus of a cell reads DNA and forms an RNA molecule, the latter can be “edited” by the cell in several ways, and various “unnecessary” parts can be thrown out of it. This will radically change how the protein molecule it encodes will work.
Fesenko and his colleagues studied how this process, which scientists call alternative splicing, occurs in the cells of one of the most primitive and ancient multicellular living organisms – the mosses Physcomitrella patens.
As the scientist tells, initially his team tried to understand what functions alternative versions of proteins can perform, the instructions for assembling which are in the moss genes. To do this, they exposed it to various stressful 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 had almost no effect on the latter’s work.
As noted by Fesenko, the reviewers of the article and the editors of the magazine first assumed that Russian researchers could make a mistake in conducting mass spectrometric analysis. The discovery was believed only after Fesenko and his colleagues 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.
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.