Protein pairs feel the heat
Computer simulations have shown that pairs of proteins bound to each other undergo a profound change in their relative motion as they heat up, a phenomenon that could provide clues to how proteins interact to govern living cells.
Simulations predict the effects of temperature on protein motion.
The molecular dynamics simulations, the product of an international collaboration led by ORNL researcher Jeremy Smith, are currently being pursued on the Cray XT4 Jaguar supercomputer. The simulations set the stage for neutron scattering experiments to test the theory by measuring protein motion.
Jeremy, who leads the ORNL Center for Molecular Biophysics and also holds a University of Tennessee-ORNL Governor’s Chair, collaborated with researchers from the University of Heidelberg in Germany. Their study has been accepted for publication in Physical Review Letters.
“The living cell is a network of proteins that talk to each other by interacting, sometimes transiently, sometimes for long periods of time. These interactions are important at every stage of cell function. Understanding the physical nature of these associations will help us to comprehend why they form and when,” Jeremy says.
The simulations performed by his team followed how a pair of interacting proteins move relative to each other as temperature increases.
Internal motions in proteins and many other materials undergo a rapid softening at a certain temperature, in a phenomenon called the “glass-to-liquid” or simply “glass” transition. The new simulations show that there is also a glass transition in the way the proteins in a pair, or ‘complex,’ move relative to each other.
At very low temperatures, around -200ºC, protein complexes are frozen stiff in a glassy state. But at around -40ºC, they suddenly free themselves up and behave like molecules in a liquid, diffusing randomly relative to each other, all while still remaining in touch, Jeremy says.
“The motion may in the future become measurable using specialized spectrometers at the Spallation Neutron Source, as neutron scattering has historically been a major technique for examining glass transition behavior,” Jeremy says. “Moreover, our team is wasting no time pushing forward with our calculations with a massive, 3.5-million-atom simulation of a thousand interacting proteins running on the ORNL Jaguar Cray XT4 supercomputer, even as the PRL article goes to press.”—B.C.
Article retrieved from ORNL Reporter
