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Mechanical Network in Titin Immunoglobulin from Force Distribution Analysis

Figure 4

Overlap of the mechanical and coevolutionary network.

(A) Heatmap of the clustered, symmetric coupling matrix containing ΔΔE values for each pair of residues, interaction interface residues were excluded. The cluster containing residues important for mechanical stability is marked in blue (augmented plot). Heatmap colors range from blue for ΔΔE = 0 to yellow for high ΔΔE values. (B) Comparison of evolutionary and mechanical couplings. Inter-side chain forces and evolutionary couplings ΔΔE are shown as barplots and sorted in descending order; interface residues were excluded. The six residues forming a highly connected cluster via evolutionary couplings, colored blue, are found to be among the highest values. The average error in the (dimensionless) values is <5 as estimated from equilibrium data (Figure 1B). (C) Structural overlap of the evolutionary with the mechanical network. The six clustered residues shown in blue in (B) mapped as spheres/sticks onto the 1WAA structure. Sticks are colored with and spheres with ΔΔE. SCA identifies the six residues as highly coevolved, edges show couplings between these residues with ΔΔE>0.7. The secondary structure was colored with to give an overview of the overall force distribution.

doi: https://doi.org/10.1371/journal.pcbi.1000306.g004