Fig. 2

An example of protein-protein interactions with some of the interface residues forming simultaneous inter and intra protein interactions. This example corresponds to a bacterial lipase in complex with cognate foldase. Complex form (PDB code: 2es4) (a, b) and unbound form of lipase (PDB code: 1cvl) (c, d). (a) An interface residue Arg 308 (shown in red colour) of lipase (backbone shown in green) is engaged in bifurcated interactions within and across proteins. B chain corresponds to cognate foldase and is shown in pink colour. (b) Zoom-up of this interface region. Side chains of interacting residues across chain are shown in pink colour. Side chains of interacting residues within lipase are shown in green colour and from foldase in pink colour. Interactions are marked in pink and green dashes, respectively. Interacting residue names and numbers are marked. (c) Uncomplexed form of lipase. Side chains of residue, Arg 308, and residues within interacting distance within lipase are shown, as in (a), in red and green colour, respectively. (d) Zoom-up of the same as in (b) but for the uncomplexed form. Interactions within lipase are remarkably well-preserved between the uncomplexed and complexed forms of lipase. This interaction is augmented by two charged-residue interactions (Glu 87 and Asp 90) which are with the foldase. This figure and Fig. 3 were generated using PyMOL [16]