title: Exploration of parameters in cryo-EM leading to an improved density map of the E. coli ribosome.
abstract: A number of image processing parameters in the 3D reconstruction of a ribosome complex from a cryo-EM data set were varied to test their effects on the final resolution. The parameters examined were pixel size, window size, and mode of Fourier amplitude enhancement at high spatial frequencies. In addition, the strategy of switching from large to small pixel size during angular refinement was explored. The relationship between resolution (in Fourier space) and the number of particles was observed to follow a lin-log dependence, a relationship that appears to hold for other data, as well. By optimizing the above parameters, and using a lin-log extrapolation to the full data set in the estimation of resolution from half-sets, we obtained a 3D map from 131,599 ribosome particles at 6.7A resolution (FSC=0.5).
authors.affiliation: Wadsworth Center, Empire State Plaza, Albany, NY 12201-0509, USA.
authors.forename: Jamie
authors.initials: J
authors.lastname: LeBarron
authors.forename: Robert A
authors.initials: RA
authors.lastname: Grassucci
authors.forename: Tanvir R
authors.initials: TR
authors.lastname: Shaikh
authors.forename: William T
authors.initials: WT
authors.lastname: Baxter
authors.forename: Jayati
authors.initials: J
authors.lastname: Sengupta
authors.forename: Joachim
authors.initials: J
authors.lastname: Frank
mesh_terms: D020285:Cryoelectron Microscopy / Q000379:methods* / Q000592:standards; D004926:Escherichia coli / Q000648:ultrastructure*; D007089:Image Enhancement / Q000379:methods; D007091:Image Processing, Computer-Assisted / Q000379:methods; D012270:Ribosomes / Q000737:chemistry / Q000648:ultrastructure*