Diverging beta-turn

Backbone angles and sequence pattern for the Diverging beta-turn (key)

Superposition of the top scoring 30 true-positives

Cartoon showing conserved polar (green) and non-polar (purple) sidechains, and glycines (red dots)

This motif contains a conserved Pro-Gly-Asx which forms a Type II beta-turn followed by a moderately conserved H-bond between the Asp, Glu or Gln and the backbone nitrogen 3 residues before it. It is interesting that the transposition of just two residues causes the change from a hairpin turn to an L-shaped, diverging beta-turn. The inwardly turned polar sidechain (Asx) leads to the diverging pair of beta-strands instead of a hairpin. The diverging turn is also stabilized by a hydrophobic contact between two sidechains 6 residues apart. Following the turn is predominantly amphipathic beta-strand. A synopsis of the sequence motif is NPPGPxN, where N is non-polar and P is polar, and G is the conserved glycine. There is experimental evidence for a structure resembling this motif in a short peptide whose sequence matches this pattern (Sieber & Moe, Biochemistry 35, 181-188 (1996)).