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Scientists have discovered how our DNA can use a fast-replicating button to make new genes for rapid adaptation to our changing environment.
During a study on DNA errors, researchers from Finland’s University of Helsinki discovered that some single changes produce palindromes, which read the same backwards and forwards. Under the right conditions, it can be internalized microRNA (miRNA) genes.
These small, simple genes play an important role in the regulation of other genes. Many miRNA genes have existed for a long time in the history of evolution, but scientists discovered that in some groups of animals, such as primates, new miRNA genes suddenly appear.
“The emergence of new genes from nothing has excited researchers,” said bioinformatician Heli Mönttinen, first author of the new study.
“We now have a beautiful model for RNA gene editing.”
The errors that allow this highly efficient method of genetic engineering are called mutation models (TSMs). The TSM process of miRNA generation is faster than the generation of new functional proteins.
“DNA is copied one base at a time, and usually the changes are single base mistakes, like typing mistakes on a computer keyboard,” said project leader and bioinformatician Ari Löytynoja.
“We investigated a mechanism that makes serious mistakes, such as copy-pasting text from another source. We are particularly interested in cases where the text is copied backwards to create a palindrome.”
All RNA molecules require repeating sets of bases to lock the molecule into its functional form. The team decided to focus on microRNA genes, which are very short, including 22 base pairs.
But even with simple microRNA genes, the chance of random base changes generating these types of palindromic genes is extremely low.
Scientists are confused about where these palindromic sequences came from. It appears that TSM can rapidly generate entire DNA palindromes, creating new microRNA genes from previously uncharacterized DNA sequences.
“Within an RNA molecule, the bases of nearby palindromes can stack and form hairpin-like structures. said biotechnologist Mikko Frilander.
The entire genomes of many primates and mammals have been sequenced. By comparing these genomes using a common computer algorithm, the researchers were able to find out which species have the microRNA palindrome pair.
“With a detailed analysis of history, we can see that entire palindromes are created through single mutations,” Mönttinen. explained.
The picture below shows the process well. As the DNA sequence begins with each partner in its list of recipes, it stops when it encounters a mutation or a faulty partner.
Replication then jumps to the nearest pattern and starts repeating those instructions but backwards.
When the sequence is returned to the original pattern it creates a small palindrome that can be combined with it in a nested structure. in hair.
Model changes during DNA replication allow the creation of the optimal DNA sequence for a novel miRNA gene. This is better than the slow and gradual changes that can happen Individual building blocks.
In the first genealogy of the family, more than 6,000 of these structures were found, which was able to generate at least 18 new miRNA genes in humans. 26 percent of all miRNAs are thought to have evolved since they first appeared.
Findings such as these, which span evolutionary lines, point to a general miRNA gene regulation mechanism, and the team thinks it may also to apply the results to other RNA genes and molecules.
It seems very easy for new microRNA genes to appear that may affect human health. Some of the miRNAs associated with TSM have already been shown to have important functions, such as hsa-mir-576 which affects the antiviral response in primates.
“Many variants of TSM can be miRNA genes isolated in the human population,” the author book“this shows that TSM is working and organizing our genomes now.”
The study is published in Proceedings of the National Academy of Sciences.