title: High resolution surface structure of E. coli GroES oligomer by atomic force microscopy.
abstract: Using atomic force microscopy (AFM) in aqueous solution, we show that the surface structure of the oligomeric GroES can be obtained up to 10 angstroms resolution. The seven subunits of the heptamer were well resolved without image averaging. The overall dimension of the GroES heptamer was 8.4 +/- 0.4 nm in diameter and 3.0 +/- 0.3 nm high. However, the AFM images further suggest that there is a central protrusion of 0.8 +/- 0.2 nm high and 4.5 +/- 0.4 nm in diameter on one side of GroES which displays a profound seven-fold symmetry. It was found that GroEL could not bind to the adsorbed GroES in the presence of AMP-PNP and Mg2+, suggesting that the side of GroES with the central protrusion faces away from the GroEL lumen, because only one side of GroES was observed under these conditions. Based on the results from both electron and atomic force microscopy, a surface model for the GroES is proposed.
authors.affiliation: Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville 22908, USA.
authors.forename: J
authors.initials: J
authors.lastname: Mou
authors.forename: D M
authors.initials: DM
authors.lastname: Czajkowsky
authors.forename: S J
authors.initials: SJ
authors.lastname: Sheng
authors.forename: R
authors.initials: R
authors.lastname: Ho
authors.forename: Z
authors.initials: Z
authors.lastname: Shao
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism / Q000648:ultrastructure; D018835:Chaperonin 10 / Q000378:metabolism / Q000648:ultrastructure*; D018833:Chaperonins; D004926:Escherichia coli / Q000378:metabolism*; D029968:Escherichia coli Proteins; D006360:Heat-Shock Proteins / Q000378:metabolism / Q000648:ultrastructure; D046911:Macromolecular Substances; D018625:Microscopy, Atomic Force / Q000379:methods; D008961:Models, Structural; D011485:Protein Binding
chemical_list: D001426:Bacterial Proteins; D018835:Chaperonin 10; D029968:Escherichia coli Proteins; C028715:GroE protein, E coli; D006360:Heat-Shock Proteins; D046911:Macromolecular Substances; D018833:Chaperonins