Department of Structural Biology

Prof. Dr. Werner Kühlbrandt, Director

Introduction and overview
The main aim of the Department is to understand the structure and function of membrane proteins and large membrane protein complexes, as determined by electron cryo-microscopy (cryoEM) and x-ray crystallography. CryoEM of macromolecular assemblies is undergoing a revolution at the moment (Kühlbrandt, Science 2014), largely due to the development of new direct electron detectors, to which the Department and the Max Planck Society have contributed.

Membrane proteins play crucial roles in virtually all biomedical processes. It is therefore essential to under-stand exactly how they work. This requires structures at atomic, or near-atomic resolution. To obtain these structures is challenging for several reasons: Many membrane proteins are fragile and tend to denature upon isolation; complexes can rarely be over-expressed or reconstituted, because they consist of many different membrane protein components; mem¬brane proteins, and especially membrane protein complexes, are difficult to crystallize.

CryoEM is ideal for investigating membrane protein complexes, because it does not depend on crystals. Samples are studied either in detergent (or amphipol) solution by single-particle cryoEM, or directly in the membrane by electron cryo-tomography (cryoET). Single-particle cryoEM has recently achieved resolutions that rival or even surpass x-ray crystallography.

The past three years have been a particularly stimulating and exciting time. We have considerably expanded the scope of membrane proteins and membrane systems we investigated during this period, not least in response to the numerous requests for promising collaborations from leading groups in membrane protein research well beyond Frankfurt and Germany. All in all, the past three years have been our most productive period to date. So far we have determined the structures of 18 different membrane protein assemblies by single-particle cryoEM at 4.2 to 9 Å, and of 15 by cryoET and sub-tomogram averaging at 18 to 30 Å resolution. The structures we determined have led to a plethora of fascinating and unexpected insights. In the next three to five years, we will make use of the outstanding cryoEM equipment that Max Planck funding has enabled us to build up, to take the currently investigated membrane proteins and protein complexes to higher, hopefully near-atomic resolution. This will provide us with a yet more detailed understanding of their molecular mechanisms.

Projects

cryoEM of multy-enzyme complexes

ATP synthases (Werner Kühlbrandt, Thomas Meier)

ATP synthases

Respiratory chain complexes (Werner Kühlbrandt)

Respiratory chain complexes

CryoET of mitochondria (Werner Kühlbrandt)

CryoET of mitochondria
Archaeal membrane protein complexes

Membrane transporters, channels and enzymes
(Özkan Yildiz, Werner Kühlbrandt)

Membrane transporters, channels and enzymes
Equipment

Contact:

Max Planck Institute of Biophysics

Prof. Dr. Werner Kühlbrandt, Managing Director
Department of Structural Biology
Secretary: Monika Hobrack

Phone: +49 (0) 69 6303-3001
Fax: +49 (0) 69 6303-3002
E-mail: monika.hobrack(at)biophys.mpg.de

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