Collective Dynamics Differentiates Functional Divergence in Protein Evolution
Figure 2
Plot and ribbon diagram of the dynamics of the three ancestral proteins characterized by slowest collective mode.
(A) The first two principal components of AncCR, AncGR1 and AncGR2 plotted against each other. The principal components were found via a Singular Value Decomposition of the G matrix (See Methods). Higher order modes are mostly orthogonal or mixed and therefore not represented here. (B) 3D structures of AncCR, AncGR1 and AncGR2 colored by residue fluctuation. The critical mutations in AncCR and AncGR1 have greater flexibility and thus, higher binding promiscuity. AncGR2 has much lower flexibility in general amongst these residues and therefore more selective binding. The S212Δ mutation also rigidifies the lower loop at the bottom end of h10 by shortening the loop and removing degrees of freedom. This also alters the packing of h10 (the frontmost helix) and decreases flexibility.