On the Origin of New Genes in Biological Evolution

A gene is a complex molecular adaptation that requires multiple different signals on DNA, which ensure that the gene can be transcribed into RNA and translated into protein. Because of this complexity it has long been thought that new genes do not originate do novo (from scratch), but from the duplication of existing genes. However, research from the last 15 years has disproven this belief. New genes frequently originate de novo. Most pertinent work arrives at this conclusion by comparing the DNA of many closely related genomes. A complementary approach is experimental. It introduces random mutations into nongenic DNA and asks how often genes or their parts originate from such mutations. I discuss recent high throughput experiments from my lab that ask how often DNA mutations create new promoters, core elements of bacterial genes that are necessary to drive a gene’s transcription into RNA. Based on more than 600’000 DNA mutations, we show that 3 percent of random DNA mutations create new promoters in genomic DNA, and 9 percent do so in random, synthetic DNA. I will discuss the reasons why promoters are so likely to originate de novo, and especially so in random DNA. Our work suggests that evolution can create a central gene part so easily that its creation has to be suppressed in genomic DNA to avoid adverse consequences to an organism.