CHAMPAIGN, Ill. In two new studies, researchers provide the first detailed view of the elaborate chemical and mechanical interactions that allow the ribosome the cell's protein-building machinery to insert a growing protein into the cellular membrane.
The first study, in Nature Structural and Molecular Biology, gives an atom-by-atom snapshot of a pivotal stage in the insertion process: the moment just after the ribosome docks to a channel in the membrane and the newly forming protein winds its way into the membrane where it will reside.
A collaboration between computational theoretical scientists at the University of Illinois and experimental scientists at University of Munich made this work possible. Using cryo-electron microscopy to image one moment in the insertion process, the researchers in Munich were able to get a rough picture of how the many individual players the ribosome, membrane, membrane channel and newly forming protein come together to get the job done. Each of these structures had been analyzed individually, but no previous studies had succeeded in imaging all of their interactions at once.
"The computational methodology contributed by the Illinois group was crucial in interpreting the new cryo-EM reconstruction in terms of an atomic level structure, and testing the interpretation through simulation," said co-author Roland Beckmann at the University of Munich. "Our joint study is unique in so closely and successfully combining experimental and computational approaches."
To image the ribosome's interaction with the membrane, Beckmann's team used small disks of membrane held together with belts of engineered lipoproteins. University of Illinois biochemistry professor Stephen Sligar developed and pioneered the use of these "nanodiscs."
The Illinois team used the cryo-EM images as well as detailed structural information about the ribosome and other molecules to construct an atom-by-atom mod
|Contact: Diana Yates|
University of Illinois at Urbana-Champaign