TRP120-1TR selectively binds to GC-rich DNA.

<p>(A-B) HSQC spectra of ¹⁵N-labeled TRP120-1TR with GC-rich DNA at pH 7.0 or pH 5.5. TRP120-1TR (68 μM) alone (black) and with a 10-fold molar equivalent of unlabeled DNA (red, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0194891#pone.0194891.t001" target="_blank">Table 1</a>) in 20 mM Tris pH 7.0 containing 100 mM NaCl or in 10 mM phosphate pH 5.5 containing 100 mM NaCl are shown. The lines highlight Asn or Gln side chain NH₂ peaks that show distinctly different chemical shifts in the bound form. (C-D) HSQC spectra of ¹⁵N-labeled TRP120-1TR with AT-rich DNA probe at pH 7.0 or pH 5.5. TRP120-1TR (30 μM) alone (black) and with a 10-fold molar equivalent of unlabeled DNA (blue, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0194891#pone.0194891.t001" target="_blank">Table 1</a>) in 20 mM Tris pH 7.0 containing 100 mM NaCl or in 10 mM phosphate pH 5.5 containing 100 mM NaCl are shown.</p

Far-UV CD spectra of TRP120-1TR and TRP120-2TR.

<p>The CD spectrum of TRP120-1TR was measured in Tris pH 7.0 containing 300 mM NaCl (blue). The CD spectra of TRP120-2TR were measured at three different pHs—phosphate pH 7.0 (green), phosphate pH 6.0 (red), and citrate pH 4.5 (gray) containing 100 mM NaCl. Secondary structure content of TRP120 constructs was estimated by BestSel analysis (bottom).</p

DNA probes used in NMR titrations.

<p>DNA probes used in NMR titrations.</p

NMR spectra of TRP120-1TR at different pHs.

<p>HSQC spectra of ¹⁵N-labeled TRP120-1TR were collected at four different pHs—Tris pH 7.0 (black), phosphate pH 6.5 (red), phosphate pH 6.0 (green), and phosphate pH 5.5 (blue) containing 100 mM NaCl.</p

Sedimentation velocity profiles of TRP120-1TR and TRP120-2TR proteins.

<p>The molecular weights of TRP120-1TR and -2TR proteins were determined by sedimentation velocity experiments. Sedimentation coefficient distribution <i>c(s)</i> profile for TRP120-1TR and TRP120-2TR show one major species, which corresponds to the molecular weight of 12.3 or 22.2 kDa, respectively. The observed molecular weights indicate that both TRP120 constructs are monomers in solution.</p

TR units of TRP120.

<p>(A) Domain organization of TRP120 and sequences of each TR unit. The primary sequences of TR units are shown with residues that differ between TR units highlighted in yellow (top). The sequence was analyzed by secondary structure (middle) and disorder (bottom) predictions. Predicted α-helical and β-strand regions are indicated by H and E, respectively. (B) SDS-PAGE of purified TRP120-1TR and TRP120-2TR proteins. Molecular weights for TRP120-1TR and -2TR proteins are 11.5 and 20.3 kDa, respectively, but the proteins migrate at twice their expected size.</p