4N0D

Crystal structure of the K345L variant of the Gi alpha1 subunit bound to GTPgammaS

Summary for 4N0D

• Entry DOI: 10.2210/pdb4n0d/pdb
• Related: 1AS2 1BH2 1GFI 1GIA 1GIL 1SVK 2ZJY 3D7M 4N0E
• Descriptor: Guanine nucleotide-binding protein G(i) subunit alpha-1, SULFITE ION, MAGNESIUM ION, ... (5 entities in total)
• Functional Keywords: rossmann fold, guanine nucleotide binding protein, gdp, gtp, magnesium binding, hydrolase
• Biological source: Rattus norvegicus (brown rat,rat,rats)
• Cellular location: Nucleus: P10824
• Total number of polymer chains: 1
• Total formula weight: 41170.75

Authors

Thaker, T.M.,Preininger, A.M.,Sarwar, M.,Hamm, H.E.,Iverson, T.M. (deposition date: 2013-10-01, release date: 2014-03-12, Last modification date: 2023-09-20)

Primary citation

Thaker, T.M.,Sarwar, M.,Preininger, A.M.,Hamm, H.E.,Iverson, T.M.
A Transient Interaction between the Phosphate Binding Loop and Switch I Contributes to the Allosteric Network between Receptor and Nucleotide in G alpha i1.
J.Biol.Chem., 289:11331-11341, 2014

PubMed Abstract: Receptor-mediated activation of the Gα subunit of heterotrimeric G proteins requires allosteric communication between the receptor binding site and the guanine nucleotide binding site, which are separated by >30 Å. Structural changes in the allosteric network connecting these sites are predicted to be transient in the wild-type Gα subunit, making studies of these connections challenging. In the current work, site-directed mutants that alter the energy barriers between the activation states are used as tools to better understand the transient features of allosteric signaling in the Gα subunit. The observed differences in relative receptor affinity for intact Gαi1 subunits versus C-terminal Gαi1 peptides harboring the K345L mutation are consistent with this mutation modulating the allosteric network in the protein subunit. Measurement of nucleotide exchange rates, affinity for metarhodopsin II, and thermostability suggest that the K345L Gαi1 variant has reduced stability in both the GDP-bound and nucleotide-free states as compared with wild type but similar stability in the GTPγS-bound state. High resolution x-ray crystal structures reveal conformational changes accompanying the destabilization of the GDP-bound state. Of these, the conformation for Switch I was stabilized by an ionic interaction with the phosphate binding loop. Further site-directed mutagenesis suggests that this interaction between Switch I and the phosphate binding loop is important for receptor-mediated nucleotide exchange in the wild-type Gαi1 subunit.

PubMed: 24596087
DOI: 10.1074/jbc.M113.539064

Experimental method

X-RAY DIFFRACTION (1.55 Å)