Figure 6
(a) Citrate-bound and citrate-free structure of the CitAP-PAS domain, as used for model-building. The citrate-bound structure (PDB ID: 2J80) is shown in grey, with the closed lid, containing the minor loop (residues 99–104), colored in red. Citrate is depicted as yellow van der Waals (vdW) surface. The corresponding citrate-free structure was obtained from a 100 ns MD simulation of the citrate-bound structure. For clarity, only the opened lid is shown (colored in blue). (b) Best model obtained from MD simulations. The BsLA and CitAP-PAS domains of the dimer are colored as in Fig. 5c. The catalytic triad of the lipase is shown in yellow. (c) Schematic illustration of a potential mechanism for the regulation of BsLA activity. The citrate-induced rearrangement of the CitAP-PAS and BsLA domains relative to each other results in the exposure of additional hydrophobic surface patches (marked by asterisks) which allows for increased binding of Triton-X100 to BsLA, which acts as an inhibitor of BsLA.
