Structure of ribosomes from Thermomyces lanuginosus by electron microscopy and image processing.

Multivariate statistical analysis and hierarchical ascendant classification techniques have been used to sort electron images of ribosomes from the thermophilic fungus Thermomyces lanuginosus into their characteristic views. Three predominant views were elucidated, called here overlap, non-overlap and top, showing reproducible detail approaching 1.8 nm resolution. The overlap and non-overlap forms of the fungal ribosomes appeared to be similar to those from the eubacterium Escherichia coli, despite differences in rRNA composition. The non-overlap projection predominated for the fungal complexes, suggesting different adsorption properties for ribosomes from the two species. Additionally, the top view has not been previously described for eubacteria. No major morphological differences could be detected between the fungal and eubacterial ribosomes at the resolution achieved in this study, suggesting a strong conservation of tertiary structure of this macromolecular complex despite the evolutionary gap between these two organisms.