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Figure 5.
Fig. 5. Hexameric model of ClpA. Electrostatic potential
surface of the modeled planar ClpA hexagon as rendered in GRASP,
with negative potential in red, positive in blue, and neutral in
white. a, the hexagonal ring is viewed along the 6-fold axis
with the D1 domains facing out. The hexagon has a crenated edge
and maximum diameter of 170 Å. The larger crenations are
made by the six N-domains, which are attached to the outer edge
of the D1 domains; the smaller crenations are formed by
extensions of the D2-small domains. b, the D2 side is facing
out, showing the wide opening of the central cavity (red) and
residues forming part of the ClpP loop (yellow). c, side view of
the modeled ClpA hexagonal ring. The height is about 87 Å.
The six subunits are shown in different colors. D1 and D2 from
the same ClpA subunit are tilted with respect to the ring axis
and make little contact with each other. Each domain makes
extensive contacts with both D1 and D2 of a neighboring subunit.
d, cross section through the center and parallel to the 6-fold
axis of the modeled ClpA hexagonal ring. The surface of the
central cavity is colored to show the three negatively charged
belts (red) and the hydrophobic surfaces surrounding the
channels (gray). The borders of the cavity are outlined in
black. The two constrictions and the two compartments are as
labeled. The positions for the three remaining ClpP loop are
indicated in yellow.
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