A. Robetta generated model of the Gifsy-1 Xis residues 1 to 72. Red ribbons indicate α-helices. Yellow ribbons indicate β-sheets. The numbers next to the model delimit predicted resolved motifs and are colored according to the corresponding ribbon structure: Helix 1 = C18 to L20; Helix 2 = S24 to K32; β-sheet structure = S46 to S68. Proline residues involved in the "Proline loop" are indicated by ball and stick models (P39, P41, P43) and are indicated by grey numbers. B-D. Robetta 3-dimensional Structure prediction of Gifsy-1 Xis compared to empirical structure determinations. B. Tn916 Xis NMR structure ; C. Gifsy-1 Xis de novo Robetta prediction; D. lambda Xis . Red arrows indicate "wing" structures. Blue arrows indicate positioning loops. Proline loop motifs are indicated by rendered ball-and-stick atom structures.