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Probing the molecular mechanism of heterotrimeric G‐protein signaling using high‐resolution NMR
Author(s) -
Abdulaev Najmoutin G,
Ramon Eva,
Ngo Tony,
Brabazon Danielle M,
Marino John P,
Ridge Kevin D
Publication year - 2007
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.21.6.a982-d
Subject(s) - heterotrimeric g protein , g protein , g protein coupled receptor , chemistry , transducin , g beta gamma complex , gtp' , biophysics , rhodopsin , gs alpha subunit , stereochemistry , signal transduction , crystallography , biochemistry , biology , enzyme , retinal
The structural basis for activation of heterotrimeric (α β γ) G‐proteins by G‐protein coupled receptors (GPCRs) is not well understood. Using the rhodopsin/transducin system, conformational changes in Gα accompanying heterotrimer formation and activated GPCR (R∗) catalyzed GDP/GTP exchange are being tracked by high‐resolution NMR. We have shown that an 15 N‐labeled Gα chimera (ChiT) that displays relatively well‐dispersed 2D spectra and uniform line widths undergoes aluminum fluoride induced perturbations in switch II and at the C‐terminus; some anticipated R∗‐ and GTP‐induced perturbations in these same regions are already evident upon heterotrimer formation, likely providing kinetic advantages in R∗/G‐protein coupling; R∗‐ and Gβ γ‐released exchanged ChiT displays further C‐terminal perturbation and increased conformational flexibility of switch II, which may be important for Gα/effector interactions and GTP hydrolysis; the GDP‐released, R∗‐bound state of ChiT shows severe line broadening suggestive of a dynamic intermediate that results from changes in the R∗‐interacting N‐ and C‐termini; and N‐ and C‐terminal mutations can have long‐range consequences on ChiT conformation, particularly in switch II. These results provide new insights into the mechanism of signal propagation from R∗ to the G‐protein. Support by NIH, Robert A. Welch Foundation, and Spanish Ministry of Science.