© Ari LöytynojaResearchers studied an error mechanism in DNA replication, and noticed that some errors create palindromes that can fold into hairpin structures.
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.
All RNA molecules require palindromic runs of bases that lock the molecule into its functional conformation.
Importantly, the chances of random base mutations gradually forming such palindromic runs are extremely small, even for the simple microRNA genes.Hence, the origin of these palindromic sequences has puzzled researchers. Experts at the Institute of Biotechnology, University of Helsinki, Finland, resolved this mystery, describing
a mechanism that can instantaneously generate complete DNA palindromes and thus create new microRNA genes from previously noncoding DNA sequences.
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