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Figure 4.
Figure 4. Reversible Activation of DegS(A) The present
structural data allow the description of three different states
I, II, and III, which are defined by the conformation of the
activation domain (Act: loops L1/L2/LD) and of loop L3. The
molecular surfaces of the respective trimers are represented
using a specific color code for the defining structural elements
(red: peptide-free, green: peptide-bound conformation). The
corresponding protomers are shown in a ribbon presentation.
Structure III represents a hybrid structure with the activation
domain in its active and loop L3 in its inactive
conformation.(B) Stereo plot showing the active state of the
activation domain with the newly formed interactions between
loops L3/L2 of one subunit (green) and L1*/LD* of the molecular
neighbor (light green). The model is shown together with the
final 2Fo-Fc electron density map calculated at 2.4 Å
resolution and contoured at 1.2 σ.(C) The ribbon plot shows the
protease domain of DegS with mapped thermal motion factors
(blue: rigid parts, red: flexible parts). The relevant active
site loops are labeled. Note that only loops comprising the
activation domain (L1, L2, LD) become more rigid, whereas loop
L3 is still flexible. The average B values for the protease
domain, LD, L1, L2, L3 are 41.2, 87.3, 70.9, n.d., 69.3 for the
uncomplexed and 71.3, 61.0, 58.6, 110.5, 128.1 for the active
form, respectively.
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