Classification of cryo-electron sub-tomograms using constrained correlation

摘要: Cryo-electron tomography (CET) is currently the only three-dimensional imaging technique capable of visualizing macromolecules in their cellular context at close-to-native conditions with a resolution nanometer range. An important component for analysis data classification, which should discriminate among various macromolecules, conformational changes and interaction partners. Missing structure factors, typically wedge-shaped region Fourier space if single-axis tilting performed, hamper classification cryo-electron tomographic data. Here, we describe method (3D) sub-tomograms extracted from tomograms, takes missing wedge into account provides reliable results. The similarity individually aligned scored by constrained correlation. Subsequently, they are clustered based on pairwise correlation values. In order to demonstrate feasibility this approach, apply proposed simulated chaperone thermosome different conformations. By comparison principal components resulting matrix show that metric significantly less prone orientation compared unconstrained Moreover, our an experimental dataset GroEL without GroES, where achieve distinct discrimination between putative GroEL/GroES complexes.