Did Early Functional Proteins Use Metal Ions to Bind ATP?

Abstract

In early life forms, the first proteins were likely composed of a limited set of amino acid building blocks. Previous work in the Seelig lab has produced random libraries of 85 amino acid-long proteins with ATP binding affinity, made from varying subsets of the 20 modern amino acids. By characterizing these proteins’ binding mechanisms and properties, we hope to gain insight into the nature of early functional proteins. Here, we took initial steps to analyze the metal ion affinity of one such protein composed of five types of amino acids. Further analysis will confirm the dependence of ATP binding on metal ions and extend these investigations to other selected protein variants.