Sawsan Wehbi

The paper investigates whether tryptophan was present in LUCA by analyzing the evolution of tryptophanyl-tRNA synthetase and finds that W usage originated in Bacteria with later horizontal transfer to Archaea.

The paper infers the order of amino acid recruitment into the genetic code by analyzing ancestral protein domain frequencies, finding smaller amino acids were added earlier and metal-binding/sulfur-containing amino acids earlier than previously thought.