6 research outputs found

    Internal backbone dynamics of PCNA in solution measured by <sup>15</sup>N relaxation.

    No full text
    <p>The order parameter S<sup>2</sup> for backbone HN bonds are plotted for those residues whose <sup>15</sup>N T<sub>1</sub>, T<sub>2</sub>, and <sup>15</sup>N{<sup>1</sup>H} NOE values could be measured and analyzed. The location of the secondary structure elements along the PCNA sequence is indicated by red and blue boxes for α-helices and β-strands, respectively. The last five residues at the C-terminal end are not seen in the crystal structure and therefore an order parameter was not calculated, but these residues have the smallest heteronuclear NOEs and the largest T<sub>2</sub> times, indicating that they are the most flexible residues in the protein (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0048390#pone.0048390.s001" target="_blank">Figure S1</a>). The regions of the graph corresponding to the IDCL (residues 117–134), the βD2−βE2 loop (184–195), and the C-terminus (252–261) are shaded in yellow. Inset: Representation of the PCNA backbone structure as a coil whose thickness is proportional to the order parameter S<sup>2</sup> of the backbone NH bond of the corresponding residue. For simplicity only one of the protomers is shown, but the data correspond to measurements done on the homotrimer. For the residues whose order parameter could not be calculated the thickness was interpolated based on the solid line joining the available values plotted in the graph. Helices and strands are colored in red and blue, and the three most flexible regions are colored in yellow (as in the graph). The loops with high relative disorder are labeled using the same nomenclature as in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0048390#pone-0048390-g001" target="_blank">Figure 1</a>.</p

    Chemical shift perturbations of PCNA backbone amide resonances caused by PIP-box peptides.

    No full text
    <p>The top and middle panels show the CSP values for each PCNA residue in the presence of a 1.2 or 1.6 excess (on a monomer basis) of p21<sup>20</sup> or p21<sup>12</sup> peptides, respectively. Under the experimental conditions used PCNA is saturated with the peptides (we calculate that 99.9 and 99.8% of the PCNA molecules are bound to the p21<sup>20</sup> or the p21<sup>12</sup> peptide, respectively). The bottom panel represents the CSP values in the presence of a 7.8 excess of the ING1<sup>22</sup> peptide. The inset shows the CSP experienced by PCNA residue H44 at increasing concentrations of the peptide with error bars spanning twice the estimated uncertainty in the CSP values (±0.005 ppm), which is the average CSP value. The line is the best fit to a model of one set of identical binding sites.</p
    corecore