The evolution of a genetically encoded amino acid alphabet

RiboEvo Special Seminar

Life on our planet has evolved to construct itself from two distinct types of polymer - nucleic acid and protein - linked by an interface known as the genetic code. By ~3 billion years ago, evolution had standardized each biopolymer to comprise a specific repertoire, or alphabet, of monomeric building blocks: 4 nucleotides and 20 amino acids. Even the interface had arrived at a standard genetic code specifying exactly which amino acid is "meant" (encoded) by each possible 3-nucleotide genetic code-word (codon). Here I will present three aspects of research to understand how and why this fundamental evolutionary outcome emerged, with an emphasis on the amino acid alphabet.

I will begin by summarizing previous work that reveals the standard genetic code as decidedly non-random in terms of the pattern by which amino acids are assigned to codons. Through a brief discussion of possible interpretations for this finding, I will turn to current research that seeks to make sense of evolution's "choice" of amino acids from a larger pool of chemical possibilities. I will then finish by describing a new project that seeks to reconcile different lines of evidence for the origin and growth of the amino acid alphabet - including a potential future collaboration with GA Tech's research into the origin of ribosomal peptide synthesis.

For more information contact Prof. Loren Williams (404-894-9752).