Three-dimensional Structure of 50 S Escherichia Coli Ribosomal Subunits Depleted of Proteins L7/L12.

A structural study of Escherichia coli 50 S ribosomal subunits depleted selectively of proteins L7/L12 and visualized by low-dose electron microscopy has been carried out by multivariate statistical analysis, classification schemes and the new reconstruction technique from single-exposure, random-conical tilt series. This approach has allowed us to solve the three-dimensional structure of the depleted 50 S subunits at a resolution of 3 nm−. In addition, two distinct morphological populations of subunits (cores) have been identified in the electron micrographs analyzed and have been separately studied in three dimensions.