Relative deuterium uptake profiles for native and hyperphosphorylated tau at 1.52 s of D₂O exposure.

<p>The native HDX profile (black bars) is shown directly below the tau domain structure and NMR-derived secondary structure map[<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0120416#pone.0120416.ref018" target="_blank">18</a>]. On the secondary structure map, yellow arrows indicate β-sheet propensity, green cylinders represent residual polypropylene helices and red cylinders denote regions with significant (> 18%) α-helical propensity. The hexapeptide regions are boxed in red. The hyperphosphorylated HDX profile (green and blue bars) is shown below the native profile. Blue bars indicate the presence of at least one phosphate on the segment indicated.</p

Histograms showing the distribution of agreement with the HDX data (Pearson coefficient) within the FRODAN ensembles.

<p>Each ensemble consists of 30,000 candidate structures, initialized based on pdb coordinates provided by the Zweckstetter group [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0120416#pone.0120416.ref018" target="_blank">18</a>], and optimized using the FRODAN algorithm. Examples of structures associated with various R-value ‘bins’ are shown above, with the ‘most representative’ structures at the far right. <b>A</b>. The native ensemble. <b>B</b>. The hyperphosphorylated ensemble.</p

Workflow from raw data to deuterium uptake kinetics for typical peptides from the native and hyperphosphorylated protein.

<p><b>A</b>. Raw data for four peptides (columns) each with fits to the isotopic distribution to determine deuterium uptake (filled circles) at three different timepoints (rows). <b>B</b>. The resulting kinetic profile for each peptide, with single exponential fit (solid line) to extract <i>k</i>_obs. The calculated ‘random coil’ profile (dotted line, filled triangles) is shown for comparison.</p

Most representative structures from the native and hyperphosphorylated ensembles, colored by PF.

<p><b>A</b>. Most representative structure for the native ensemble (<i>R</i> = 0.30), which exhibits a global ‘S’-shaped fold with sequestration of the hexapeptides. <b>B</b>. Most representative structure for the hyperphosphosphorylated ensemble (<i>R</i> = 0.29) showing release of the N- and C-termini, full exposure of H2 and a few regions of residual structure, including around H1.</p