The origin of genetic code: Study finds textbook version needs revision

[sfmatheson (Stephen Matheson)]

I posted the actual paper last month.

Order of amino acid recruitment into the genetic code resolved by LUCA's protein domains

Very interesting new paper from the Masel lab at the University of Arizona*. Below are some excerpts that I found important. From the Intro: Previous analyses focused on the age of orthologous gene families (20–22); ours infers which protein domains date back to LUCA. Protein domains are the basic units of proteins, that can fold, function, and evolve independently (23). Proteins often contain multiple protein domains, each of which might have a different age (Fig. 1). For the purpose of inferring ancient amino acid usage, what matters is the age of the protein domain, not that of the whole protein that it is part of. Beginning of the Discussion: The evolution of the current genetic code proceeded via stepwise incorporation of amino acids, driven in part by changes in early life’s environment and requirements. Contemporary proteins retain information about which amino acids were part of the code at the time of their birth, allowing us to infer the order of recruitment on the bas…