Fig. 2: Conserved Phe residues within the NTD are critical to sHSP assembly, stability and chaperone function.
From: Mechanism of small heat shock protein client sequestration and induced polydispersity
a Cα root-mean-square deviation (r.m.s.d.) comparison between contracted and expanded states of apo-37, highlighting variability in the NTD (colored). b and c Distance measurements between neighboring NTD chains within a dimer (NTA and NTB) for contracted and expanded states of apo-37 (b) and apo-75 (c) showing Cα distances between Lys16 sites and intrachain Phe11–Ala20. d Comparison of α1 helices from apo-37 (contracted: red; expanded: blue) and apo-75 (yellow). e Sequence alignment of ‘aromatic’ and ‘conserved’ NTD regions across sHSPs, with mutated Phe residues in mjHSP16.5 highlighted (top). Pseudo-atomic model of complete NTDs (NTA and NTB) with labeled Phe residues (bottom). f Hydrodynamic radii of mjHSP16.5 wildtype (mj-wt) and variants (mj-1x and mj-3x) in the apo-state and lysozyme-bound states (12:1 and 2:1 chaperone:client monomeric ratios) after 75 °C incubation. Independent experiments for each reaction were n = 3 for mj-wt, mj-1x, and mj-3x apo and 2:1 reactions, n = 4 for mj-1x and mj-3×12:1 reaction, and n = 5 for mj-wt 12:1 reaction. g Hydrodynamic radius (n = 3) and representative NS-EM micrographs of mj-6x variant at 25 °C in the apo-state (scale bar = 50 nm). h and i NS-EM micrographs (scale bar = 50 nm) and Feret diameter distributions (raincloud plots) for mj-wt, mj-1x, and mj-3x variants in the apo-state and lysozyme-bound states after 75 °C incubation. Box and whisker plots in panels f, g, and i describe the interquartile distribution (25th, 50th, and 75th percentile) with the central line in the box representing the median and the whiskers representing 1.5 times the interquartile distance from the nearest hinge. Data points residing outside of the whiskers in panel i represent outliers in the quartile analysis. White circles in panels f and g represents the mean of each distribution. Micrographs in panels g and h are representative of at least five independent observations. Source data for panels f–i are provided as a Source Data file.
