Science reports:

Life today depends on proteins, cellular workhorses that do everything from flex muscles to ferry oxygen. And proteins, in turn, depend on RNA, which carries the recipes for making them and also helps with their assembly. In modern cells, large protein-based enzymes help connect RNA snippets to amino acids, the building blocks of proteins. Then, the RNA- and protein-based cellular machine called the ribosome stitches the amino acids together into a protein chain, reading the correct sequence from a longer strand of messenger RNA. But billions of years ago, before the evolution of the enzymes and the ribosome, how could life’s first proteins have been constructed?

Researchers say they’ve now come up with a plausible route by which RNA and amino acids could have paired up to assemble small proteins called peptides, without the help of complex enzymes or the ribosome. The work, published today in Nature, offers a glimpse of how RNA might have helped form the first simple proteins, an event that could have set the stage for evolution.

“This is the first step to allowing life’s information molecules to encode peptides,” says Matthew Powner, a chemist at University College London (UCL) who led the study. Thomas Carell, a chemist at the Ludwig Maximilian University of Munich, says the study “gives wonderful insights” into “one of the big riddles in prebiotic chemistry.” [Continue reading…]