3-DIMENSIONAL RECONSTRUCTION OF THE SEVENFOLDED FORM OF BACILLUS-SUBTILIS GRO EL CHAPERONIN

Bacillus subtilis grown at 42°C produces a major form of Gro EL-like chaperonin that has been analyzed by electron microscopy. Most of the views show a clear sevenfold symmetry when studied by rotational analysis. The particles were classified into defined families by multivariate analysis and supervised fuzzy-set classification methods, and those belonging to a sevenfold family were averaged to produce a two-dimensional representative projection. These selected particles were then used, when tilted by 55° in the microscope goniometer stage, as the starting projections for a three-dimensional reconstruction protocol based on the random conical tilt series method. The resulting reconstruction shows the Gro EL-like chaperonin from B. subtilis as a cylindrical body with seven well defined lobules arranged almost parallel to the longitudinal axis of the particle. There is a channel that is placed along this axis and appears fully open in both sides. The geometry of the channel is polar and presents differences in both faces of the particle. © 1990.