Nonenzymatic, prebiotic aminoacylation couples chirality of RNA and protein

Abstract

Life as we know it depends on the homochirality of nucleic acids and proteins. However, there is no widely accepted explanation for why life uses only D-sugars for nucleic acids and L-amino acids for proteins. Here we demonstrate a prebiotically plausible method of nonenzymatic aminoacylation in a water ice-eutectic phase. These reactions produce high yields of aminoacyl-tRNAs, which are active in translation. Surprisingly, we discovered these nonenzymatic aminoacylation conditions were stereoselective, favoring coupling of amino acids and RNA of “opposite” L- and D- configurations. D-RNA shows greater aminoacylation yields for L-amino acids. The opposite was true for L-RNA, which had greater yields with D-amino acids. Nucleic acid backbone chirality influencing stereoselectivity of aminoacylation presents the missing link in the origin of modern biochemistry. This phenomenon provides insight into the chirality of the RNA world, and helps to explain the “opposite” stereochemistry of modern biomolecules.