Molecular insights into historical constraints on evolution

Our living world is the result of a complex history spanning billions of years. Scientists have access to artifacts of this history, namely the fossil record and the genomes of many different living organisms. But there are surprisingly limited means with which to infer the exact evolutionary history that resulted in modern biota. It is difficult to reconcile fossil morphology on the one hand, and genetic composition and diversification over time on the other, when so little about the biological behavior of ancestral organisms can be reconstructed to link these data. This limitation makes it difficult to approach intriguing questions of whether the evolutionary paths that produced modern organisms were highly deterministic (i.e., life as a factory) or inherently dominated by chance (i.e., life as a casino parlor). Did life in the past function or evolve similarly to life today? Did the biology of ancestral organisms, the functions of their proteins or other factors inherently limit their ability to evolve into modern forms? To attempt to overcome these historical limitations, we will resurrect 1.3 to 3.6 billion year old genes inside modern E. coli microbes. These ancient genes will produce revenant or ‘Lazarus’ proteins that are thought to more closely resemble the proteins that composed ancestral organisms. By engineering revenant proteins inside modern organisms, we can characterize their biological function and observe the holistic effects that they have on the cell’s behavior. This will produce an experimental system consisting of viable modern-ancient hybrid E. coli amenable to biological, biochemical and genetic characterization, at least three scholarly manuscript that will describe the adaptation of ancient genes in the modern cell, and at least five presentations of results at scientific and public fora. The impact of this project will be to establish a new paleogenetic approach that will permit experimental study of historical aspects of evolution.