Three-dimensional (3D) Reconstruction of Single particles from Electron Micrographs

The research of our laboratory focuses on the three-dimensional structure determination of macromolecular assemblies using electron microscopy combined with image processing.

Early reconstruction of complex I from Yarrowia lipolytica



Currently we are investigating enzyme complexes of the respiratory chain and macromolecules with related functions. We are studying the structure and subunit arrangement of Complex I from different species and the arrangement and interaction of respiratory chain molecules within the mitochondrial membrane. The importance of understanding the function and relationships between enzymes in the respiratory chain is highlighted by the fact that many mitochondrial diseases can be traced back to defects in the genes encoding complex I. Examples are LHON-disease (Lebers hereditary optic neuropathy), Lighs disease and Kearns-Sayre syndrome.

A strong component of out research is the development of new image processing algorithms and techniques. Our current research is geared towards the development of better image alignment and classification methods and the analysis and development of reliability criteria for three-dimensional reconstruction.

Previous work includes the reconstruction of the large ribosomal subunit from E.coli, and the development of the Random Conical Reconstruction technique. Development of further image analysis techniques for single particles include work on the determination and correction of the electron microscope transfer function, the development of a number of new reconstruction algorithms (weighted back-projection techniques for conical geometry and later for arbitrary geometry, Radon transform inversion algorithms with non-tomographic noise filtration), alignment methods for two- and three-dimensional projection alignment and pattern analysis methods (nonlinear mapping, Gibbs sampling algorithm for the classification of images).

Through many collaborations we have been involved in the structure determination of the V1-ATPase, of the calcium release channel and ribosome/channel complexes.

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