Fig. 1.

Structure of CeGS in complex with CeGN³⁴. (A) Domain architecture of CeGS (GT-B fold) and CeGN (GT-A fold). (B) Interaction of CeGN³⁴ to CeGS determined by fluorescence polarization. K_d value ± SEM is the average of three independent experiments carried out in duplicate. (C) Structure of the CeGS tetramer bound to the CeGN³⁴ peptide. (D) Comparison of CeGS protomers (blue) and the budding yeast ScGS (PDB ID code 3NAZ, gray). The N-terminal extension of CeGS (green) and C-terminal extensions of CeGS (red) and ScGS (orange) are highlighted. Phosphoregulatory sites 2 (S12), 2a (T19), 3a (S654), 3b (S658), and 3c (S662) and the allosteric regulatory site (Arg cluster) on the CeGS protomer are shown as ball and stick models with violet-colored carbon atoms. (E) Peel away surface representations of the CeGS–CeGN complex with contact residues (CeGS, Upper; CeGN, Lower). (F) Detailed stereoview of the CeGS–CeGN³⁴ complex. CeGS is shown in blue and CeGN in green. Side chain residues that make direct contacts are shown as sticks with colored heteroatoms (oxygen, red; nitrogen, dark blue; sulfur, yellow). Glycine residues are depicted as blue spheres, and carbonyl oxygens are shown as red spheres. Hydrogen bonds are depicted as dotted lines.