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Figure 4.
Docking of AcrA and AcrB directed by the cross-linking data.
(A) AcrA and AcrB interaction hotspots predocking. Cross-linking
hotspots on the AcrA and AcrB surfaces predocking, colored on a
gradient reflecting all cross-linking data: from dark blue near
negative Cys-substituted residues (no cross-link), through green
near residues with a bias to the L linker, to yellow/orange/red
with increasing proximity to positives linked by both S and L
linker. The TolC interface of the adaptor hairpin (23) is in
magenta. The arrow indicates rotation from side to front view.
(B) Docked complex of AcrA on an AcrB subunit. The 4 AcrA
adaptor domains are shown in green shades, with 2 helical turns
of the MP concave surface in yellow, β-turn Gly residues in
white and the N-terminal residue in blue. The transporter
periplasmic subdomain colors are as in Fig. 3B. Cross-sections
at 2 levels of the complex (indicated by the brackets) are boxed
on the right and illustrate the domain–domain contacts of the
adaptor MP domain (i) and β-barrel and lipoyl domains (ii).
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