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|2v4z, resolution 2.80Å ()|
THE CRYSTAL STRUCTURE OF THE HUMAN G-PROTEIN SUBUNIT ALPHA (GNAI3) IN COMPLEX WITH AN ENGINEERED REGULATOR OF G-PROTEIN SIGNALING TYPE 2 DOMAIN (RGS2)
"Regulator of G-protein signaling" (RGS) proteins facilitate the termination of G protein-coupled receptor (GPCR) signaling via their ability to increase the intrinsic GTP hydrolysis rate of Galpha subunits (known as GTPase-accelerating protein or "GAP" activity). RGS2 is unique in its in vitro potency and selectivity as a GAP for Galpha(q) subunits. As many vasoconstrictive hormones signal via G(q) heterotrimer-coupled receptors, it is perhaps not surprising that RGS2-deficient mice exhibit constitutive hypertension. However, to date the particular structural features within RGS2 determining its selectivity for Galpha(q) over Galpha(i/o) substrates have not been completely characterized. Here, we examine a trio of point mutations to RGS2 that elicits Galpha(i)-directed binding and GAP activities without perturbing its association with Galpha(q). Using x-ray crystallography, we determined a model of the triple mutant RGS2 in complex with a transition state mimetic form of Galpha(i) at 2.8-A resolution. Structural comparison with unliganded, wild type RGS2 and of other RGS domain/Galpha complexes highlighted the roles of these residues in wild type RGS2 that weaken Galpha(i) subunit association. Moreover, these three amino acids are seen to be evolutionarily conserved among organisms with modern cardiovascular systems, suggesting that RGS2 arose from the R4-subfamily of RGS proteins to have specialized activity as a potent and selective Galpha(q) GAP that modulates cardiovascular function.
Structural determinants of G-protein alpha subunit selectivity by regulator of G-protein signaling 2 (RGS2)., Kimple AJ, Soundararajan M, Hutsell SQ, Roos AK, Urban DJ, Setola V, Temple BR, Roth BL, Knapp S, Willard FS, Siderovski DP, J Biol Chem. 2009 Jul 17;284(29):19402-11. Epub 2009 May 28. PMID:19478087
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
[RGS2_HUMAN] Inhibits signal transduction by increasing the GTPase activity of G protein alpha subunits thereby driving them into their inactive GDP-bound form. May play a role in leukemogenesis. Plays a role in negative feedback control pathway for adenylyl cyclase signaling. Binds EIF2B5 and blocks its activity, thereby inhibiting the translation of mRNA into protein.
About this Structure
- Kimple AJ, Soundararajan M, Hutsell SQ, Roos AK, Urban DJ, Setola V, Temple BR, Roth BL, Knapp S, Willard FS, Siderovski DP. Structural determinants of G-protein alpha subunit selectivity by regulator of G-protein signaling 2 (RGS2). J Biol Chem. 2009 Jul 17;284(29):19402-11. Epub 2009 May 28. PMID:19478087 doi:10.1074/jbc.M109.024711
- ↑ Heximer SP, Lim H, Bernard JL, Blumer KJ. Mechanisms governing subcellular localization and function of human RGS2. J Biol Chem. 2001 Apr 27;276(17):14195-203. Epub 2001 Jan 30. PMID:11278586 doi:10.1074/jbc.M009942200
- ↑ Gu S, Anton A, Salim S, Blumer KJ, Dessauer CW, Heximer SP. Alternative translation initiation of human regulators of G-protein signaling-2 yields a set of functionally distinct proteins. Mol Pharmacol. 2008 Jan;73(1):1-11. Epub 2007 Sep 27. PMID:17901199 doi:10.1124/mol.107.036285
- ↑ Wu HK, Heng HH, Shi XM, Forsdyke DR, Tsui LC, Mak TW, Minden MD, Siderovski DP. Differential expression of a basic helix-loop-helix phosphoprotein gene, G0S8, in acute leukemia and localization to human chromosome 1q31. Leukemia. 1995 Aug;9(8):1291-8. PMID:7643615
- ↑ Nguyen CH, Ming H, Zhao P, Hugendubler L, Gros R, Kimball SR, Chidiac P. Translational control by RGS2. J Cell Biol. 2009 Sep 7;186(5):755-65. PMID:19736320 doi:jcb.200811058