Structural features of predicted permissive stretches determined by structure prediction and crystal structures. Secondary structure (SS) and RSA were predicted from sequence using NetSurfP [45] and calculated from crystal structures using the DSSP algorithm [63]. A crystal structure for GpsA was not available. The RSA of a stretch is defined as the maximum RSA of its constituent sites. The correlations of RSA and SS between predictions and crystal structures at all residues were computed by distance correlation [65]. The crystal structure was not resolved in TpiA PSIV and AtpA PSI. See Methods for more precise definitions of these calculations. (DOCX 68 kb)