Genome complexity: making new RNA genes (Introduction)

by David Turell , Sunday, December 10, 2023, 19:25 (139 days ago) @ David Turell

By mutations in copying:

https://phys.org/news/2023-12-genes.html

"The complexity of living organisms is encoded within their genes, but where do these genes come from? Researchers at the University of Helsinki resolved outstanding questions around the origin of small regulatory genes, and described a mechanism that creates their DNA palindromes. Under suitable circumstances, these palindromes evolve into microRNA genes.

"The human genome contains ca. 20,000 genes that are used for the construction of proteins. Actions of these classical genes are coordinated by thousands of regulatory genes, the smallest of which encode microRNA molecules that are 22 base pairs in length. While the number of genes remains relatively constant, occasionally, new genes emerge during evolution. Similar to the genesis of biological life, the origin of new genes has continued to fascinate scientists.

***

"In their project, the researchers studied errors in DNA replication. Ari Löytynoja, the project leader, compares DNA replication to typing of text.

"'DNA is copied one base at a time, and typically mutations are erroneous single bases, like mis-punches on a laptop keyboard. We studied a mechanism creating larger errors, like copy-pasting text from another context. We were especially interested in cases that copied the text backward so that it creates a palindrome."

"Researchers recognized that DNA replication errors could sometimes be beneficial. They described these findings to Mikko Frilander, an expert in RNA biology. He immediately saw the connection to the structure of RNA molecules.

""In an RNA molecule, the bases of adjacent palindromes can pair and form structures resembling a hairpin. Such structures are crucial for the function of the RNA molecules," he explains.

***

"By focusing on humans and other primates, researchers in Helsinki demonstrated that the newly found mechanism can explain at least a quarter of the novel microRNA genes. As similar cases were found in other evolutionary lineages, the origin mechanism appears universal.

"In principle, the rise of microRNA genes is so easy that novel genes could affect human health. Heli Mönttinen sees the significance of the work more broadly, for example, in understanding the basic principles of biological life.

"'The emergence of new genes from nothing has fascinated researchers. We now have an elegant model for the evolution of RNA genes," she highlights.

Comment: copying backwards is a mutation mechanism which has given beneficial RNA genes. Most mutations are bad so this finding is unusual. Perhaps God at work in a dabble programming.