Unraveling the active conformation of urotensin II

J Med Chem. 2004 Mar 25;47(7):1652-61. doi: 10.1021/jm0309912.


Urotensin II (U-II) is a disulfide-bridged undecapeptide recently identified as the ligand of an orphan G-protein-coupled receptor. Human U-II (H-Glu-Thr-Pro-Asp-cyclo[Cys-Phe-Trp-Lys-Tyr-Cys]-Val-OH) has been described as the most potent vasoconstrictor compound identified to date. With the aim of elucidating the active conformation of hU-II, we have performed a spectroscopic analysis of hU-II minimal active fragment hU-II(4-11) in different environmental conditions. The analysis indicated that hU-II(4-11) was highly structured in the anisotropic membrane mimetic SDS solution, showing a type II' beta-turn structure, which is almost unprecedented for L-amino acid peptides. Micelle bound structure of hU-II(4-11) was then compared with those of four synthetic analogues recently synthesized in our lab, bearing modified Cys residues at position 5 and/or position 10 and characterized by different levels of agonist activity. The structures of the active compounds were found to be very similar to that of hU-II(4-11), while a barely active compound does not show any propensity to beta-turn formation. Furthermore, distances among putative pharmacophoric points in the structures of the active compounds obtained in SDS solution are in good agreement with those found in a recently described non-peptide agonist of the hU-II receptor. A type II' beta-turn structure was already found for the somatostatin analogue octreotide. On the basis of the similarity of the primary and 3D structures of U-II and somatostatin analogues and on the basis of the sequence homology between the GPR14/UT-II receptor and members of the somatostatin receptor family, a common evolutionary pathway for the signal transmission system activated by these peptide can be hypothesized.

MeSH terms

  • Chromans / chemistry
  • Circular Dichroism
  • Humans
  • Magnetic Resonance Spectroscopy
  • Micelles
  • Models, Molecular
  • Peptide Fragments / chemistry
  • Peptides, Cyclic / chemistry
  • Protein Conformation
  • Receptors, G-Protein-Coupled / agonists
  • Receptors, G-Protein-Coupled / chemistry
  • Sodium Dodecyl Sulfate
  • Solutions
  • Stereoisomerism
  • Urotensins / chemistry*


  • 3-(4-chlorophenyl)-3-(2-(dimethylamino)ethyl)isochroman-1-one
  • Chromans
  • Micelles
  • Peptide Fragments
  • Peptides, Cyclic
  • Receptors, G-Protein-Coupled
  • Solutions
  • UTS2R protein, human
  • Urotensins
  • aspartyl-cyclo(penicillamyl-phenylalanyl-tryptophyl-lysyl-tyrosyl-cysteinyl)valine
  • Sodium Dodecyl Sulfate
  • urotensin II