Solution structure of a new hypothalamic neuropeptide, human hypocretin-2/orexin-B.
Orexin-A and orexin-B (also called hypocretin-1 and hypocretin-2, respectively) are novel hypothalamic neuropeptides encoded by a single mRNA transcript; they stimulate food intake. We have determined the three-dimensional solution structure of human hypocretin-2/orexin-B using two-dimensional 1H-NMR data and dynamical simulated annealing calculations. On the basis of NOEs, 3JHNalpha coupling constants and hydrogen-deuterium exchange rates together with chemical shift indices, human hypocretin-2/orexin-B was deduced to consist of two alpha-helices connected with a short linker in both H2O and 30% trifluoroethanol solutions. The helical axis of helix I is oriented about 60-80 degrees relative to helix II. Hybrid distance geometry and simulated-annealing protocols were used to generate an ensemble of 30 structures with no constraint violations greater than 0.03 nm for distances and 3 degrees for angles. In addition, human hypocretin-2/orexin-B shares a similar secondary-structural motif with human neuropeptide Y. This result can form the basis for further study on ligand-receptor recognition of human orexin receptors.
Lee
J H
JH
Department of Biochemistry College of Science, Yonsei University, Seoul, Korea.
Bang
E
E
Chae
K J
KJ
Kim
J Y
JY
Lee
D W
DW
Lee
W
W
D000595:Amino Acid Sequence; D000818:Animals; D002942:Circular Dichroism; D006801:Humans; D007031:Hypothalamus / Q000737:chemistry*; D047908:Intracellular Signaling Peptides and Proteins; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009478:Neuropeptide Y / Q000737:chemistry; D009479:Neuropeptides / Q000737:chemistry* / Q000235:genetics; D018377:Neurotransmitter Agents / Q000737:chemistry* / Q000235:genetics; D009765:Obesity / Q000209:etiology / Q000378:metabolism; D000068797:Orexins; D017433:Protein Structure, Secondary; D017386:Sequence Homology, Amino Acid; D012996:Solutions
C000596229:HCRT protein, human; D047908:Intracellular Signaling Peptides and Proteins; D009478:Neuropeptide Y; D009479:Neuropeptides; D018377:Neurotransmitter Agents; D000068797:Orexins; D012996:Solutions