Structural host-microbiota interaction networks
(a) A, B, C, D are host proteins and P is pathogenic protein. Protein A has two interfaces: through blue interface it binds to B and through grey interface it binds to C and D. C and D proteins employ similar interfaces to bind to A. So, endogenous interfaces mimic each other. Pathogenic protein P has similar interface as B and competes to bind to the blue interface on A. In this case, an exogenous interface mimics an endogenous interface. (b) The F1L protein of variola virus interacts with human BID protein (5ajj:AB.pdb) and inhibits apoptosis in the host cell by hijacking the interface between human BID-BCLXL (4qve:AB.pdb): an exogenous interface mimicking an endogenous one. Human MCL1 protein binds to human BID (5c3f:AB.pdb) in a very similar fashion that BCLXL does: endogenous interfaces mimicking each other.