Fig. 1: Overview of engineered nodes in the S6, GA, and GB networks.
From: Design and characterization of a protein fold switching network
S6 is the origin sequence in the engineering process. SI and S’I are separate nodes and are loop-size variants of the S-fold, both having protease inhibitor functions. The SI branch of the mutational path leads to a node with the A-fold and HSA binding function. The S’I branch of the path leads to a node with the B-fold and IgG binding function. The S/A node (blue and red circles) includes proteins Sa1, Sa2, A1, and A2. The S/B node (blue and green circle) includes proteins Sb3, Sb4, Sb5, B3, and B4. The A and B paths themselves intersect at an A/B node (green and red circles) at which A- and B-folds are nearly iso-energetic and bifunctional. The S and S’ branches continue and connect with many other natural sequences in the α/β plait super-fold family.
