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Fig. 1.1
DnaK structure and folding cycle.
a
Model for the Hsp70 folding cycle. The DnaKﾷATP
complex has weak substrate affinity. ATP binding to the NBD (
blue
) stabilizes a compact domain
arrangement, which leaves the SBD (
yellow
and
green
) in an open conformation. This conforma-
tion exhibits dynamic interactions with the substrate (indicated in
brown
). ATP hydrolysis stimu-
lated by DnaJ (
1
) causes a conformational change in the NBD that triggers formation of the closed
SBD conformation, which has higher affinity for the substrate, resulting in a stable substrate com-
plex. The binding of the NEF GrpE (
2
) promotes a slight opening of the NBD, which results in the
release of ADP from DnaK. The cycle is reset (
3
) when a new ATP molecule binds to the NBD,
triggering the release of NEF and substrate.
b
Crystal structure of the DnaKﾷATP complex. The
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