As a group, the bacteria lost fewer folds, although those that were parasites or obligate parasites retained only a minimalist repertoire of folds. Their strategy was to take advantage of the protein machinery available in their hosts.
The multicellular Eukarya, a group that includes humans, retained the largest repertoire of fold architectures.
We are the keepers of everything. We have the largest repertoire that there is, Caetano-Anolls said. The eukaryotes evolution into large, multicellular bodies that could live in diverse environments relied on an extensive library of protein architectures, he said.
The new study divides the evolution of protein architectures into three phases. First, there was a common world, with a large collection of protein folds available to all. The researchers call this a period of architectural diversification.
Next came a period, called superkingdom specification, during which the three superkingdoms emerged. The third phase, organismal diversification, saw an explosion of inventiveness in protein architectures, particularly among the Eukarya.
Caetano-Anolls stressed that any attempt to build an evolutionary tree of life is limited by the type of data used to populate the tree. He compared the task to that of writing a history of building architecture by analyzing the changes over time that occurred in a single building component, such as the window.
The window is a good element for studying the history of buildings, he said. But it can be misleading because windows may have their own pace of historical change.
Caetano-Anolls said he believes his teams tree of protein architectures is robust because it is rooted in two axiomatic statements that seem to yield consistent and r
|Contact: Diana Yates|
University of Illinois at Urbana-Champaign