At the Origin of Life: How Did Folded Proteins Evolve?

Proteins are essential building blocks of living cells; indeed, life can be viewed as resulting substantially from the chemical activity of proteins. Because of their importance, it is hardly surprising that ancestors for most proteins observed today were already present at the time of the ‘last common ancestor’, a primordial organism from which all life on Earth is descended. Yet folded proteins are too complex to have arisen de novo. How then did they evolve? We are pursuing the hypothesis that folded proteins evolved by fusion and recombination from an ancestral set of peptides, which emerged in the context of RNA-dependent replication and catalysis (the “RNA world”). Systematic studies should allow a description of this ancient peptide set in the same way in which ancient vocabularies have been reconstructed from the comparative study of modern languages