Fig. 3: SAXS demonstrates that nucleotide binding defective TG2 mutants that constitutively adopt the open state dimerize in the presence of GTP.
a, b Titration of 0 mM to 5 mM GTP into TG2 R580K. a Kratky curves for the titration series are shown in shades of blue (dark blue, 0 mM to light blue, 5 mM). b The Guinier Rg decreases as the conformational ensemble of TG2 R580K is driven to adopt a saturated conformational state. The experimental molecular weight calculated from the Porod Volume is shown on the secondary Y-axis (red). c The open state dimer generated from the crystal packing of the open state crystal structure of TG2. Left, the open state dimer colored by monomer. Right, the open state dimer colored by domain. d Nucleotide bound TG2 R580K (light blue) can be described as an open state dimer in solution, as demonstrated by CRYSOL fit of the open state dimer (dark blue). Wildtype TG2 bound to GTP (light green) and the CRYSOL fit to the closed state monomer (dark green) are shown for comparison. The Guinier Rg and the model Χ2 are shown in the legend. e Left, the two monomers within the open state dimer (orange and yellow) form a highly similar GTP binding pocket to the closed state monomer (black). Right, proposed nucleotide binding sites within the open state dimer.
