Study Offers Insight into the Origin of the Genetic Code

A study of enzymes that load amino acids onto transfer RNAs offers new insights into the evolutionary origins of the modern genetic code. Researchers from the University of Illinois (UI) focused on aminoacyl tRNA synthetases, enzymes that "read" the genetic information embedded in transfer RNA molecules and attach the appropriate amino acids to those tRNAs. When a tRNA is charged with its amino acid, it carries it to the ribosome, a cellular "workbench" on which proteins are assembled, one amino acid at a time.

The team determined the relative ages of different protein regions called domains and made the simple assumption that domains found in only a few organisms are likely younger, and those that appear in organisms from every branch of the tree of life are likely the most used and most ancient.

Gustavo Caetano-Anollés, UI professor of crop science and bioinformatics who led the team said, "The most ancient protein domains were enriched in dipeptides with amino acids encoded by the most ancient synthetases. And these ancient dipeptides were present in rigid regions of the proteins." He added that the domains that appeared after the emergence of the genetic code were enriched in dipeptides present in highly flexible regions, associating genetics with protein flexibility.

For more details about this study, read the news release at: http://news.illinois.edu/news/13/0826genetic_code_origins_GustavoCaetano-Anolles.html.