Genes are the building blocks of life, and the genetic code provides the instructions for the complex processes that make organisms function. But how and why did it come to be the way it is? A recent study from the University of Illinois Urbana-Champaign sheds new light on the origin and evolution of the genetic code, providing valuable insights for genetic engineering and bioinformatics.
“We find the origin of the genetic code mysteriously linked to the dipeptide composition of a proteome, the collective of proteins in an organism,” said corresponding author Gustavo Caetano-Anollés, professor in the Department of Crop Sciences, the Carl R. Woese Institute for Genomic Biology, and Biomedical and Translation Sciences of Carle Illinois College of Medicine at U. of I.
Caetano-Anollés’ work focuses on phylogenomics, which is the study of evolutionary relationships between the genomes of organisms. His research team previously built phylogenetic trees mapping the evolutionary timelines of protein domains (structural units in proteins) and transfer RNA (tRNA), an RNA molecule that delivers amino acids to the ribosome during protein synthesis. In this study, they explored the evolution of dipeptide sequences (basic modules of two amino acids linked by a peptide bond), finding the histories of domains, tRNA, and dipeptides all match.
Life on Earth began 3.8 billion years ago, but genes and the genetic code did not emerge until 800,000 million years later, and there are competing theories about how it happened.
Some scientists believe RNA-based enzymatic activity came first, while others suggest proteins first started working together. The research of Caetano-Anollés and his colleagues over the past decades supports the latter view, showing that ribosomal proteins and tRNA interactions appeared later in the evolutionary timeline.