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Lab site: Rubinstein Lab

Brief Biography

John Rubinstein obtained his BSc from the University of Guelph in 1998. He received his PhD from Cambridge University (2002) where he worked in Medical Research Council laboratories under the supervision of Sir John E. Walker and Dr. Richard Henderson. Dr. Rubinstein was a Postdoctoral Research Associate at the MRC Laboratory of Molecular Biology before returning to Canada for a National Cancer Institute of Canada (NCIC) postdoctoral fellowship at the Banting and Best Department of Medical Research. He joined the Research Institute of The Hospital for Sick Children in 2006. Dr. Rubinstein is a CIHR New Investigator.

Mailing Address
Molecular Structure and Function Program , Rm. 3330
The Hospital for Sick Children
555 University Avenue
Toronto, Ontario
Canada
M5G 1X8

Research Interests

Structural biology and electron cryomicroscopy
Structure and function of macromolecular assemblies
Membrane protein complexes
Bioenergetics

Research Activities

Summary

Electron cryomicroscopy (cryo-EM) of macromolecular assemblies has become an important technique in structural biology. The method allows biologists to bridge the resolution gap between images of cells from light microscopy and conventional electron microscopy and the high-resolution information available from X-ray crystallography and NMR spectroscopy.

ATP synthase

ATP synthase is the central enzyme in biological energy metabolism. Our work aims to combine cryo-EM and structures derived from X–ray crystallography to build an empirical model of intact ATP synthase. Aspects of this project involve a close collaboration with the research group Sir John Walker (MRC Dunn Human Nutrition Unit, Cambridge, UK). The ATP synthase is of medical interest because it presents a target for the generation of specific inhibitors that may serve as therapeutic agents for the treatment of bacterial infections, ischemia-reperfusion injury and angiogenesis in cancer.

 

Figure 1;
A 3-D model of the ATP synthase from cryo-EM with an atomic model of the F1-c10 subcomplex docked into it.

Figure 2
Class averages of cryo-EM images of the ATP synthase arranged into a movie reveal its 3-D structure.

Download figure 2 [ .mov format ] (Available in QuickTime)

TonB dependant nutrient transport

Gram-negative bacteria couple the import of nutrients such as iron and vitamin B12 across their outer membrane to the proton motive force across their cytoplasmic membrane. This process depends on the soluble TonB protein and membrane bound ExbB-ExbD protein complex. Through a collaboration with Prof. Mirek Cygler (NRC-BRI, Montréal) we are using EM to study the structure of the membrane bound ExbB-ExbD complex. Understanding nutrient import in Gram-negative bacteria, which include E. coli and the P. aeruginosa (a major opportunistic pathogen for people with burns or cystic fibrosis), is essential for developing therapies against infection by these organisms.

Method development

Cryo-EM is an evolving method with great unexplored potential for high-resolution structure determination and the investigation of conformational changes and dynamic complexes. New techniques that will be developed, in part in this laboratory, will expand the potential of cryo-EM to address questions about macromolecular assemblies that currently frustrate crystallographic and spectroscopic approaches. The understanding of molecular processes in biology has often been tightly coupled to the development of new methods. In this tradition, our research program is a composite of the investigation of systems of fundamental biological importance with the development of electron cryomicroscopy methods. Through this combination, we intend to solve problems of importance to biology and medicine and expand our potential to address new questions in structural biology.

External Funding

Research in the laboratory is funded by start-up grants from The Hospital for Sick Children and operating grants from the Canadian Institutes of Health Research. A state-of-the-art cryo-EM facility was recently established at The Hospital for Sick Children with a Leaders Opportunity Fund award to Dr. Rubinstein from the Canadian Foundation for Innovation.

Publications

A listing of Dr. Rubinstein's articles is available on Pubmed. »»