Researchers at the University of Helsinki have discovered a mechanism to generate energy instantly. DNA Palindromes can lead to the creation of new microRNA genes from non-coding DNA sequences. This discovery was made while studying DNA replication errors and their effects. RNA Molecular structure provides new insights into the origins of genes.
The complexity of living things is encoded in our genes, but where do those genes come from? Researchers at the University of Helsinki have solved an open question about the origins of small regulatory genes and discovered that their DNA We explained the mechanism that creates palindromes. Under the right circumstances, these palindromes evolve into microRNA genes.
Genes and proteins: the building blocks of life
The human genome contains approximately one genome. 20,000 genes used to build proteins. The actions of these classical genes are coordinated by thousands of regulatory genes, the smallest of which encodes microRNA molecules that are 22 base pairs long. Although the number of genes is relatively constant, new genes may appear during the process of evolution. Similar to the origin of biological life, the origin of new genes continues to fascinate scientists.
solve palindrome puzzles
All RNA molecules require palindromic bases that lock the molecule into a functional conformation. Importantly, even in simple microRNA genes, it is extremely unlikely that random base mutations would gradually form such palindromic sequences. Therefore, the origin of these palindromic sequences has puzzled researchers. Experts from the Institute of Biotechnology at the University of Helsinki in Finland have described a mechanism that allows them to instantly generate complete DNA palindromes, thereby creating new microRNA genes from previously non-coding DNA sequences, and this The mystery has been solved.
Insights into DNA replication
In a project funded by the Academy of Finland, researchers studied errors in DNA replication. Project leader Ari Löytynoja likens DNA replication to inputting text.
“DNA is copied one base at a time, and mutations are usually single base errors, like typos on a laptop keyboard. We copy and paste text from another context. We were particularly interested in the case of copying text backwards to create palindromes.”
RNA structure and DNA errors
Researchers recognized that DNA replication errors can be beneficial. They explained these findings to Mikko Frilander, an expert in RNA biology. He quickly understood his connection to the structure of RNA molecules.
“In RNA molecules, adjacent palindromic bases can pair up to form hairpin-like structures. Such structures are critical to the function of RNA molecules,” he explains.
The researchers decided to focus on microRNA genes because of their simple structure. Genes are very short (only a few dozen bases) and must be folded into hairpin structures to function properly.
The central insight was to model genetic history using custom computer algorithms. Postdoctoral researcher Heli Montinen says this allows for the most rigorous investigation of the origins of genes to date.
“The complete genomes of dozens of primates and mammals are known. Comparing their genomes reveals which seed Those with microRNA palindrome pairs and those without. “When we modeled the history in detail, we found that the entire palindrome was created by a single mutational event,” says Montinen.
Implications and universality
Focusing on humans and other primates, the Helsinki researchers demonstrated that the newly discovered mechanism can explain at least a quarter of novel microRNA genes. Similar cases have been found in other evolutionary lineages, so the mechanism of origin is likely to be universal.
In principle, the emergence of microRNA genes could be so simple that new genes could impact human health. Heri Montinen sees the importance of this research more broadly, for example in understanding the fundamental principles of biological life.
“The phenomenon of new genes emerging out of thin air has fascinated researchers. We now have a sophisticated model for the evolution of RNA genes,” she emphasizes. do.
Although the results are based on small regulatory genes, the researchers believe their findings can be applied to other RNA genes and molecules. For example, by using raw materials produced by newly discovered mechanisms, natural selection could produce more complex RNA structures and functions.
This study PNAS.
Reference: “Generation of de novo miRNAs by template switching during DNA replication” Heli AM Mönttinen, Mikko J. Frilander, Ari Löytynoja, November 29, 2023. Proceedings of the National Academy of Sciences.
DOI: 10.1073/pnas.2310752120