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Figure 1.
Figure 1. Structure of the Covalent Adaptor-Substrate
Complex(A) Aligned structures of the disulfide-linked
SspB-SBD^S-SssrA complex (pink/red) with the noncovalent
wild-type complex (cyan/blue; PDB code 1OU8) (Levchenko et al.,
2003). SspB is displayed in ribbon representation, and the main
chain atoms of the ssrA peptide are in stick representation. The
disulfide bond (yellow) is displayed in CPK representation.(B)
Simulated-annealing omit map of electron density for a portion
of the ssrA peptide and the disulfide crosslink to SspB. The
ssrA peptide and Cys44 of SspB were omitted during map
calculations. The 1.9 Å 2F[0] − F[C] map is contoured at
0.7σ.(C) Sequence of the ssrA tag showing sites of contact with
SspB or ClpX and the mutant cysteine used for crosslinking to
SspB.(D) Surface/stick representation of one subunit of the
covalent SspB-SBD^S-SssrA complex. Tag residues 9–11 (shown in
purple) were not visible in the crystal structure and were
modeled in an energetically favorable conformation for this
figure.
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