Protein Secondary Structure Determination by Constrained Single-Particle Cryo-Electron Tomography
Alberto Bartesaghi, Federico Lecumberry, Guillermo Sapiro, Sriram Subramanian
Structure, Volume 20, Number 12, page 2003--2013 - Dec. 2012
Research Group(s): Tratamiento de Imagenes (gti)
Department(s): Procesamiento de Señales
Download the publication : BLSS12.pdf [2.1Mo]  

Abstract

Cryo-electron microscopy (cryo-EM) is a powerful technique for 3D structure determination of protein complexes by averaging information from individual molecular images. The resolutions that can be achieved with single-particle cryo-EM are frequently limited by inaccuracies in assigning molecular orientations based solely on 2D projection images. Tomographic data collection schemes, however, provide powerful constraints that can be used to more accurately determine molecular orientations necessary for 3D reconstruction. Here, we propose ‘‘constrained single-particle tomography’’ as a general strategy for 3D structure determination in cryo-EM. A key component of our approach is the effective use of images recorded in tilt series to extract high-resolution information and correct for the contrast transfer function. By incorporating geometric constraints into the refinement to improve orientational accuracy of images, we reduce model bias and overrefinement artifacts and demonstrate that protein structures can be determined at resolutions of 8 A˚ starting from low-dose tomographic tilt series.

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» Alberto Bartesaghi
» Federico Lecumberry
» Guillermo Sapiro
» Sriram Subramanian