Scientists Film Ribosomes Building Proteins

Investigators at UC Berkeley have used an X-ray crystallography technique to record short movies of ribosomes motion, which is quite a feat considering these organelles are only 21 nanometers wide. It is hoped that by observing ribosome interaction with mRNA, we could learn how these enigmatic structures turn genetic information into proteins that serve the body.

“Scientists used to think that the ribosome made a simple two-stage ratcheting motion by rotating back and forth as it interacts with mRNA and tRNA,” said Cate [Jamie Cate, UC Berkeley associate professor in chemistry and molecular and cell biology, and a faculty scientist at Lawrence Berkeley National Laboratory. –ed.], who is also a member of the California Institute for Quantitative Biomedical Research (QB3) at UC Berkeley. “What we captured were images of the ribosome in intermediate stages between the rotations, showing that there are at least four steps in this ratcheting mechanism.”
“We suspect that the ribosome changes its conformation in so many steps to allow it to interact with relatively big tRNAs while keeping the two segments of the ribosome from flying apart,” said Cate. “It’s much more complicated than the simple ratcheting mechanism in a socket wrench.”
Cate said that while this study marked a major accomplishment in cracking open the “black box” of ribosomal function, there are far more details yet to be revealed. Advances in imaging techniques over the next decade should allow researchers to go beyond the snapshots taken in this study to high-resolution movies of a ribosome’s movements, he said.

UC Berkeley announcement: New images capture cell’s ribosomes at work, could aid in molecular war against disease …
Images: Top: Above is an entire ribosome with its changes in position color-coded — ranging from blue, indicating no movement, to red, indicating large movements. Bottom: The stages of a ribosome subunit as it moves. At the top right is its starting position; below it are pairs of images, showing three subsequent positions (still images at left, movement vectors at right). The arrows indicate the direction of movement, and the blurred lines convey motion, much like an action shot in photography.
Abstract in Science: Structures of the Ribosome in Intermediate States of Ratcheting