Chiral-Selective Aminoacylation of an RNA Minihelix

Abstract

Amino acids in natural proteins have a chiral, asymmetric center at the α carbon that is of the L -configuration. The sugar backbone of natural RNAs are also homochiral, but of the D -configuration. Because protein synthesis requires the aminoacylation of RNA, it is this step that could have provided chiral selectivity. Here we show that an RNA minihelix was aminoacylated by an aminoacyl-phosphate- D -oligonucleotide with a clear preference for L - as opposed to D -amino acids. A mirror-image RNA system showed the opposite selectivity. These results suggest the possibility that the selection of L -amino acids for proteins was determined by the stereochemistry of RNA.