Allosteric mechanisms underlie GPCR signaling to SH3-domain proteins through arrestin

Abstract

Signals from 800 G-protein-coupled receptors (GPCRs) to many SH3 domain-containing proteins (SH3-CPs) regulate important physiological functions. These GPCRs may share a common pathway by signaling to SH3-CPs via agonist-dependent arrestin recruitment rather than through direct interactions. In the present study, F-NMR and cellular studies revealed that downstream of GPCR activation engagement of the receptor-phospho-tail with arrestin allosterically regulates the specific conformational states and functional outcomes of remote β-arrestin 1 proline regions (PRs). The observed NMR chemical shifts of arrestin PRs were consistent with the intrinsic efficacy and specificity of SH3 domain recruitment, which was controlled by defined propagation pathways. Moreover, in vitro reconstitution experiments and biophysical results showed that the receptor-arrestin complex promoted SRC kinase activity through an allosteric mechanism. Thus, allosteric regulation of the conformational states of β-arrestin 1 PRs by GPCRs and the allosteric activation of downstream effectors by arrestin are two important mechanisms underlying GPCR-to-SH3-CP signaling.

Pyridoxine induces glutathione synthesis via PKM2-mediated Nrf2 transactivation and confers neuroprotection

“…DRD2 activation triggers β-arrestin2 to bind with and dimerize PKM2. DRD2 activation stimulates both the classical G protein pathway and β-arrestin-biased signaling, resulting in distinct downstream events [41][42][43] . The Gα i protein inhibitor pertussis toxin (PTX) did not affect DRD2 activation-induced PKM2 dimerization, suggesting that PKM2 dimerization is independent of the classical G protein pathway (Fig.…”

DeSiphering receptor core-induced and ligand-dependent conformational changes in arrestin via genetic encoded trimethylsilyl 1H-NMR probe

“…DeSipher β-arr1 activation by 1 H-NMR. We then incorporated TMSiPhe into functionally relevant structural motifs of β-arr1, the key signal transducer downstream of almost all 800 GPCRs encoded in the human genome, which functions not only by desensitizing membrane receptors but also by mediating independent downstream signaling after receptor activation 12,13,[15][16][17][18][19][20][21]24,25 (Fig. 3a, b).…”

“…DeSipher ligands induced polar core conformational change. Arrestin is known to be activated via both receptor-phosphorylation and active seven transmembrane 7TM core 12,13,[16][17][18]29,[41][42][43][44][45] ( Fig. 4a).…”

“…However, the application of these methods, especially the assignment of complicated multidimensional spectrum is expensive and technically challenging for most biochemistry laboratories. It has recently emerged that one-dimensional 19 F nuclear magnetic resonance (1D 19 F-NMR) is a powerful and convenient method for studying dynamic conformation changes and post-translational modification of proteins [8][9][10][11][12][13] . The advantage of this method is that, through site-specific labeling, typically only one peak is present in the 1D NMR spectra.…”

“…We show that TMSiPhe is genetically incoporated into the protein selectively by the UAG codon and that the UAG codon only encode TMSiPhe 14 . Owing to the high efficiency and fidelity of TMSiPheRS, we then applied this method to investigate the activation mechanism of arrestin, an important signal transducer downstream of most G-protein-coupled receptors (GPCRs) 12,13,[15][16][17][18][19][20][21][22][23] . In addition to desensitize the receptor, arrestins are active signaling hubs of GPCRs by scaffolding receptor signaling complexes, which recruit multiple downstream effectors, such as kinases, phosphatases, ion channels etc 12,13,[15][16][17][18][19][20][21]24,25 .…”