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The bacterial SecY/E translocation complex forms channel-like structures similar to those of the eukaryotic Sec61p
T H Meyer1, J F Ménétret, R Breitling
1Howard Hughes Medical Institute and Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, MA, 02115, USA.
Abstract:
The SecYEG complex is a major component of the protein translocation apparatus in the cytoplasmic membrane of bacteria. We have purified a translocationally active complex of the two subunits, SecY and SecE, from Bacillus subtilis. As demonstrated by electron microscopy, SecY/E forms ring structures in detergent solution and in intact lipid bilayers, often with a quasi-pentagonal appearance in projection. The particles represent oligomeric assemblies of the SecY/E complex and are similar to those formed by the eukaryotic Sec61p complex. We propose that these SecY/E rings represent protein-conducting channels and that the two essential membrane components SecY and SecE are sufficient for their formation.