Ala31-Aib32: identification of the key motif for high affinity and selectivity of neuropeptide Y at the Y5-receptor.
The turn-inducing sequence Ala-Aib introduced into positions 31 and 32 of neuropeptide Y (NPY) and its analogues has been identified as the key structure for Y(5)-receptor selectivity. Analogues of NPY and PP/NPY chimera containing the motif Ala-Aib were prepared; these peptides turned out to be selective for the Y(5)-receptor. The affinity of the NPY-based peptides was in the range of 6-150 nM, while the affinity of three (Ala-Aib)-containing PP/NPY chimera was in the range of 0.2-0.9 nM. The circular dichroism spectra of the Aib analogues in aqueous solution were all characteristic of an alpha helix; however, they had different intensities of the two negative bands at 220 and 208 nm. Affinity and selectivity for the Y(5)-receptor were correlated with the ratio of the ellipticity at 220 nm versus the one at 208 nm (R), which indicates the presence of a pronounced helix (R > 1) versus a less stabile one (R < 1). When R was in the range 0.74-0.96, the affinity at the Y(5)-receptor was in the range >5 nM, while there was complete loss of affinity at the Y(4)-receptor. R > 1.15 was associated with very high affinity at the Y(5)-receptor and weak affinity at the Y(4)-receptor. These results suggest that the selectivity of the Ala(31)-Aib(32) motif for the Y(5)-receptor derives from a specific conformation that must be correlated with the bioactive conformation of NPY at this subtype.
Cabrele
Chiara
C
Institute of Biochemistry, University of Leipzig, Talstrasse 33, 04103 Leipzig, Germany.
Wieland
Heike A
HA
Koglin
Norman
N
Stidsen
Carsten
C
Beck-Sickinger
Annette G
AG
D000409:Alanine / Q000378:metabolism*; D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution / Q000235:genetics; D000621:Aminoisobutyric Acids / Q000378:metabolism*; D000818:Animals; D001667:Binding, Competitive / Q000235:genetics; D002460:Cell Line; D002942:Circular Dichroism; D006224:Cricetinae; D008024:Ligands; D008969:Molecular Sequence Data; D009478:Neuropeptide Y / Q000138:chemical synthesis / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding / Q000235:genetics; D051381:Rats; D017476:Receptors, Neuropeptide Y / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000138:chemical synthesis / Q000378:metabolism; D013329:Structure-Activity Relationship
D000621:Aminoisobutyric Acids; D008024:Ligands; D009478:Neuropeptide Y; D017476:Receptors, Neuropeptide Y; D011993:Recombinant Fusion Proteins; C100568:neuropeptide Y5 receptor; D000409:Alanine