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. 2021 Mar 29;12:1936. doi: 10.1038/s41467-021-21953-3

Fig. 4. The C-terminal domain (CTD) is disordered, engages in transient interaction with the dimerization domain, and contains a putative helical-binding motif.

Fig. 4

A Histogram of the transfer efficiency distribution measured across the labeling positions 363 and 419 in the context of the full-length protein, under aqueous buffer conditions. B Donor–acceptor cross-correlation measured by ns-FCS (see SI). The flat correlation indicates a lack of dynamics in the studied timescale or the coexistence of two populations in equilibrium whose correlations (one correlated and the other anticorrelated) compensate each other. C Interdye distance as extracted from single-molecule FRET experiments across different denaturant concentrations. The full line represents a fit to the model in Eq. (S6), which accounts for denaturant binding. Error bars are the propagation of ±0.03 systematic error in measured transfer efficiencies (see SI). D Inter-residue distance distributions calculated from simulations (histogram) show good agreement with distances inferred from single-molecule FRET measurements (purple bar). E Scaling maps describe the average inter-residue distance between each pair of residues, normalized by the distance expected if the CTD behaved as a self-avoiding random coil. H6 engages in extensive intra-CTD interactions and also interacts with the dimerization domain. We observe repulsion between the dimerization domain and the N-terminal region of the CTD. F Two transient helices (H5 and H6) are observed in the CTD (residues 383–396 and 402–415). Both show a reduction in population in the presence of the dimerization domain at least in part because the same sets of residues engage in transient interactions with the dimerization domain. Error bars are standard error of the mean calculated from forty independent simulations. G The normalized distances are projected onto the surface to map CTD-dimerization interaction. The helical region drives intramolecular interaction, predominantly with the N-terminal side of the dimerization domain. H Helix H6 is an amphipathic helix with a polar/charged surface (left) and a hydrophobic surface (right).