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Alternate Binding Mode of C‐terminal Phenethylamine Analogs of G t α (340–350) to Photoactivated Rhodopsin
Author(s) -
Anderson Matthew A.,
Ogbay Benhur,
Kisselev Oleg G.,
Cistola David P.,
Marshall Garland R.
Publication year - 2006
Publication title -
chemical biology and drug design
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.59
H-Index - 77
eISSN - 1747-0285
pISSN - 1747-0277
DOI - 10.1111/j.1747-0285.2006.00460.x
Subject(s) - rhodopsin , phenethylamine , chemistry , stereochemistry , terminal (telecommunication) , biochemistry , computer science , retinal , telecommunications
The C‐terminus of the G α ‐subunit of transducin plays an important role in receptor recognition. Synthetic peptides corresponding to the last 11 residues of the subunit have been shown to stabilize the photoactivated form of rhodopsin, Rh*. The Rh*‐bound structure of the G t α (340–350) peptide has been determined using transferred nuclear overhauser effect NMR. In that structure, we observed two interactions between Lys341 and Phe350, a cation– π interaction between the ɛ ‐amine and the aromatic ring of Phe350 and a salt‐bridge between the ɛ ‐amine and the C‐terminal carboxylate. A series of C‐terminal phenethylamine analogs of the G t α (340–350) peptide were synthesized, lacking the C‐terminal carboxylate group, to investigate the forces that contribute to the stability of the Rh*‐bound conformation of the peptide. Rh*‐stabilization assay data suggest that the C‐terminal carboxylate is not necessary to maintain binding affinity. Transferred nuclear overhauser effect NMR experiments reveal that these C‐terminal phenethylamine peptides adopt an Rh*‐bound structure that is similar overall, but lacking some of the intramolecular interactions observed in the native Rh*‐bound G t α (340–350) structure. These studies suggest that the binding site for G t α (340–350) on Rh* is adaptable, and we propose that the charged carboxylate of Phe350 does not play a significant role in the interaction with Rh*, but helps stabilize the Rh*‐bound confirmation of the native peptide.