Is it possible to discern the evolutionary history of an organism by looking at its protein composition?
The study, in the journal Structure, reveals that after eons of gradual evolution, proteins suddenly experienced a "big bang" of innovation. The active regions of many proteins, called domains, combined with each other or split apart to produce a host of structures that had never been seen before. This explosion of new forms coincided with the rapidly increasing diversity of the three super-kingdoms of life (bacteria; the microbes known as archaea; and eucarya, the group that includes animals, plants, fungi and many other organisms).
Lead author Gustavo Caetano-Anollés, a professor of bioinformatics in the department of crop sciences at the University of Illinois and an affiliate of the Institute for Genomic Biology, has spent years studying protein structures - he calls them "architectures" - which he suggests offer a reliable record of evolutionary events.
Dr. Cartano-Anollés spoke with the Scientist Live Audio Mailbag and answered the questions sent in by the readers. Enjoy the podcast.
Studying the history of protein functions is very interesting. Can you describe how a scientist can look at a set of modern proteins and deduce its evolutionary history? (Paul S., Reading, England)
You refer to the Big Bang of protein development in which the domains of proteins increased in function. Do you have any hunches what might have caused the big bang? (Adina M., Belgrade, Serbia)
Are you saying that protein structure undergoes the same evolutionary pressures as animals? If so can you give specific examples how the environment can select for and against a particular domain? (Mario K., Munich, Germany)
All biology students learn that proteins tend to take four basic forms: primary, secondary, tertiary, and quarternary. Did these forms evolve in the same way? (Ludivine P., Tolouse, France)
How far back (on a molecular scale) can you extend the notion of evolution? For example, your theory suggests that active domains were subject to natural selection. Can the same be said about the addition of amino and carboxyl groups to long carbon chains? (Stefano G., London, England)
In physics, the Big Bang is still occurring. The universe is still expanding. Eventually, it will stop and possibly contract. Is the protein Big Bang still occurring? Any chance for a contraction? (Heinrich S., Vienna, Austria)
You say: "The history of the protein repertoire should match the history of the entire organism because the organism is made up of all those pieces." From that, one can infer from that that any given protein's repertoire should match that same protein's history. However, proteins function in similar fashions in various different organisms. Can you explain how and why this happens and how it is explained within your theory? (Patrick E. New York, USA)
