Jx. Mou et al., HIGH-RESOLUTION SURFACE-STRUCTURE OF ESCHERICHIA-COLI GROES OLIGOMER BY ATOMIC-FORCE MICROSCOPY, FEBS letters, 381(1-2), 1996, pp. 161-164
Using atomic force microscopy (AFM) in aqueous solution, we show that
the surface structure of the oligomeric GroES can be obtained up to 10
Angstrom resolution, The seven subunits of the heptamer were web reso
lved without image averaging. The overall dimension of the GroES hepta
mer was 8.4+/-0.4 nm in diameter and 3.0+/-0.3 nm high, However, the A
FM 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 di
splays a profound seven-fold symmetry, It was found that GroEL could n
ot bind to the adsorbed GroES in the presence of AMP-PNP and Mg2+, sug
gesting that the side of GroES with the central protrusion faces away
from the GroEL lumen, because only one side of GroES was observed unde
r these conditions. Based on the results from both electron and atomic
force microscopy, a surface model for the GroES is proposed.