The present can tell you a lot about the past, but you need to know where to look. A new study appearing this month in Genome Research reveals that protein architectures the three-dimensional structures of specific regions within proteins provide an extraordinary window on the history of life.
In the study, researchers at the University of Illinois describe contemporary protein architectures as molecular fossils or historical imprints that mark important milestones in evolutionary history. The research team compiled a global census of protein architectures, and used these relics to plot the emergence, diversification and refinement of each of the three superkingdoms of life: Archaea, Bacteria and Eukarya.
All proteins are composed of architectural elements, called domains, which can be identified by their structural and functional similarities to one another. Protein domains are the gears, belts, springs and motors that allow the larger protein machinery to function as it should. Every protein contains one or more of them, and proteins that perform very different tasks can contain identical domains.
Protein domains are grouped into what are called fold families and fold superfamilies. Members of a fold superfamily may differ in their underlying amino acid sequences, but retain structural and functional similarities and are evolutionarily related. Fold superfamilies are grouped together into broad categories, called folds.
The new study tracks the evolution of folds and fold superfamilies from the ancient world to the present.
Protein folds turn out to be reliable markers of evolutionary events because they are quite stable over time, said Gustavo Caetano-Anolls, a professor of crop sciences and a principal investigator on the study. Even mutations in the genes that code for them rarely change their three-dimensional structures.
Structures are highly conserved because they were important discoveries in
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University of Illinois at Urbana-Champaign