A detailed map that pinpoints the location of every atom in a 450-million-yeard-old resurrected protein reveals the precise evolutionary steps needed to create the molecules modern version, according to researchers from the University of North Carolina at Chapel Hill and the University of Oregon.
Until now, scientists trying to unravel the evolution of the proteins and other molecules necessary for life have worked backwards, making educated guesses based on modern human body chemistry. By moving forward from an ancient protein, the team laid out the step-by-step progression required to reach its current form and function.
The study appears in the Aug. 17, 2007, issue of the journal Science.
We were able to see exactly how mutations in the ancient structure led to the modern receptor, said lead author Eric Ortlund, who carried out the research as a UNC-Chapel Hill postdoctoral fellow. Ortlund is now an assistant professor of biochemistry in the Emory University School of Medicine.
In the current study, Ortlund and Matt Redinbo, a professor of chemistry, biochemistry and biophysics at UNC-Chapel Hill, generated a three-dimensional picture of the ancient receptor with an imaging technique called X-ray crystallography. The nanoscale image revealed the receptors structure, down to the placement of every atom. With the structure in place, Ortlund and his colleagues retraced evolutions path.
The researchers examined the precursor to a modern protein known as a glucocorticoid receptor. In humans, the receptor plays a crucial role, responding to the hormone cortisol and regulating the bodys stress response. The two receptor and hormone fit together as precisely as a lock and key. The precursor preferred a different hormone, so several mutations were necessary before the lock could fit the cortisol key.
The University of Oregon team, which included postdoctoral scientist Jamie Bridgham, resurrected the ancient pr
|Contact: Becky Oskin|
University of North Carolina at Chapel Hill