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About SickKids

January 12, 2012

SickKids scientists develop cutting-edge 3D structural model detailing cell’s molecular motors

Researchers from The Hospital for Sick Children (SickKids) have determined the structure of an essential type of protein, called a rotary ATPase, found in all cells. Rotary ATPases are referred to as molecular motors because rotation of part of the protein causes it to pump protons across cell membranes. Until now, there were no structural models available of an intact rotary ATPase with the necessary resolution to understand how rotation of the rotary part of the protein can lead to protons being pumped across cell membranes. The study is published in the January 12 edition of Nature.

“Our research provides a new level of understanding of the mechanism of these motors, which has implications in diverse areas,” says Dr. John Rubinstein, Scientist in the Molecular Structure and Function Program at SickKids and Assistant Professor in the Departments of Biochemistry and Medical Biophysics at the University of Toronto, who conducted the study with SickKids PhD student Wilson Lau.

In this study, the scientists developed new techniques for electron cryomicroscopy (cryo-EM) – a form of electron microscopy where samples are studied at very low temperatures – to determine the 3D map of the rotary ATPase from the bacterium T. thermophilus at a subnanometer (better than one millionth of a millimeter) resolution. These techniques included developing methods to optimize images and creating new computer algorithms used to calculate the complete 3D structure from the images they obtained.

“The findings help us understand how cells manage their energy supply, how certain bacteria, viruses and toxins enter human cells and even how certain types of tumours acidify and invade the tissue that surrounds them,” says Rubinstein.

The research was supported by the Canadian Institutes of Health Research, an Ontario Graduate Scholarship, the Ministry of Research and Innovation and SickKids Foundation.