scholarly journals Structural basis for adhesion G protein-coupled receptor Gpr126 function

2019 ◽  
Author(s):  
Katherine Leon ◽  
Rebecca L. Cunningham ◽  
Joshua A. Riback ◽  
Ezra Feldman ◽  
Jingxian Li ◽  
...  
Keyword(s):  
Binding Site ◽  
G Protein ◽  
Heart Development ◽  
Calcium Binding ◽  
Structural Basis ◽  
Calcium Binding Site ◽  
Surface Receptors ◽  
Alternatively Spliced ◽  
G Protein Coupled

AbstractMany drugs target the extracellular regions (ECRs) of cell-surface receptors. The large and alternatively-spliced ECRs of adhesion G protein-coupled receptors (aGPCRs) have key functions in diverse biological processes including neurodevelopment, embryogenesis, and tumorigenesis. However, their structures and mechanisms of action remain unclear, hampering drug development. The aGPCR Gpr126/Adgrg6 regulates Schwann cell myelination, ear canal formation, and heart development; and GPR126 mutations cause myelination defects in human. Here, we determine the structure of the complete zebrafish Gpr126 ECR and reveal five domains including a previously-unknown domain. Strikingly, the Gpr126 ECR adopts a closed conformation that is stabilized by an alternatively spliced linker and a conserved calcium-binding site. Alternative splicing regulates ECR conformation and receptor signaling, while mutagenesis of the newly-characterized calcium-binding site abolishes Gpr126 function in vivo. These results demonstrate that Gpr126 ECR utilizes a multi-faceted dynamic approach to regulate receptor function and provide novel insights into ECR-targeted drug design.

scholarly journals Structural basis for adhesion G protein-coupled receptor Gpr126 function

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Katherine Leon ◽  
Rebecca L. Cunningham ◽  
Joshua A. Riback ◽  
Ezra Feldman ◽  
Jingxian Li ◽  
...  
Keyword(s):  
Binding Site ◽  
G Protein ◽  
Heart Development ◽  
Calcium Binding ◽  
Structural Basis ◽  
Calcium Binding Site ◽  
Surface Receptors ◽  
Alternatively Spliced ◽  
G Protein Coupled

AbstractMany drugs target the extracellular regions (ECRs) of cell-surface receptors. The large and alternatively-spliced ECRs of adhesion G protein-coupled receptors (aGPCRs) have key functions in diverse biological processes including neurodevelopment, embryogenesis, and tumorigenesis. However, their structures and mechanisms of action remain unclear, hampering drug development. The aGPCR Gpr126/Adgrg6 regulates Schwann cell myelination, ear canal formation, and heart development; and GPR126 mutations cause myelination defects in human. Here, we determine the structure of the complete zebrafish Gpr126 ECR and reveal five domains including a previously unknown domain. Strikingly, the Gpr126 ECR adopts a closed conformation that is stabilized by an alternatively spliced linker and a conserved calcium-binding site. Alternative splicing regulates ECR conformation and receptor signaling, while mutagenesis of the calcium-binding site abolishes Gpr126 function in vivo. These results demonstrate that Gpr126 ECR utilizes a multi-faceted dynamic approach to regulate receptor function and provide relevant insights for ECR-targeted drug design.

scholarly journals Atomic resolution probe for allostery in the regulatory thin filament

2016 ◽  
Vol 113 (12) ◽  
pp. 3257-3262 ◽  
Author(s):  
Michael R. Williams ◽  
Sarah J. Lehman ◽  
Jil C. Tardiff ◽  
Steven D. Schwartz
Keyword(s):  
Binding Site ◽  
Human Disease ◽  
Calcium Binding ◽  
Cardiac Troponin ◽  
Thin Filament ◽  
Troponin I ◽  
Troponin T ◽  
Calcium Binding Site

Calcium binding and dissociation within the cardiac thin filament (CTF) is a fundamental regulator of normal contraction and relaxation. Although the disruption of this complex, allosterically mediated process has long been implicated in human disease, the precise atomic-level mechanisms remain opaque, greatly hampering the development of novel targeted therapies. To address this question, we used a fully atomistic CTF model to test both Ca2+ binding strength and the energy required to remove Ca2+ from the N-lobe binding site in WT and mutant troponin complexes that have been linked to genetic cardiomyopathies. This computational approach is combined with measurements of in vitro Ca2+ dissociation rates in fully reconstituted WT and cardiac troponin T R92L and R92W thin filaments. These human disease mutations represent known substitutions at the same residue, reside at a significant distance from the calcium binding site in cardiac troponin C, and do not affect either the binding pocket affinity or EF-hand structure of the binding domain. Both have been shown to have significantly different effects on cardiac function in vivo. We now show that these mutations independently alter the interaction between the Ca2+ ion and cardiac troponin I subunit. This interaction is a previously unidentified mechanism, in which mutations in one protein of a complex indirectly affect a third via structural and dynamic changes in a second to yield a pathogenic change in thin filament function that results in mutation-specific disease states. We can now provide atom-level insight that is potentially highly actionable in drug design.

scholarly journals Importance of Calcium-Binding Site 2 in Simian Virus 40 Infection

2007 ◽  
Vol 81 (11) ◽  
pp. 6099-6105 ◽  
Author(s):  
Peggy P. Li ◽  
Albert P. Nguyen ◽  
Qiumin Qu ◽  
Qumber H. Jafri ◽  
Saharat Aungsumart ◽  
...  
Keyword(s):  
Binding Site ◽  
Calcium Binding ◽  
Simian Virus 40 ◽  
Antigen Expression ◽  
Simian Virus ◽  
T Antigen ◽  
Calcium Binding Site ◽  
Viral Dna ◽  
Particle Assembly

ABSTRACT The exposure of molecular signals for simian virus 40 (SV40) cell entry and nuclear entry has been postulated to involve calcium coordination at two sites on the capsid made of Vp1. The role of calcium-binding site 2 in SV40 infection was examined by analyzing four single mutants of site 2, the Glu160Lys, Glu160Arg, Glu157Lys (E157K), and Glu157Arg mutants, and an E157K-E330K combination mutant. The last three mutants were nonviable. All mutants replicated viral DNA normally, and all except the last two produced particles containing all three capsid proteins and viral DNA. The defect of the site 1-site 2 E157K-E330K double mutant implies that at least one of the sites is required for particle assembly in vivo. The nonviable E157K particles, about 10% larger in diameter than the wild type, were able to enter cells but did not lead to T-antigen expression. Cell-internalized E157K DNA effectively coimmunoprecipitated with anti-Vp1 antibody, but little of the DNA did so with anti-Vp3 antibody, and none was detected in anti-importin immunoprecipitate. Yet, a substantial amount of Vp3 was present in anti-Vp1 immune complexes, suggesting that internalized E157K particles are ineffective at exposing Vp3. Our data show that E157K mutant infection is blocked at a stage prior to the interaction of the Vp3 nuclear localization signal with importins, consistent with a role for calcium-binding site 2 in postentry steps leading to the nuclear import of the infecting SV40.

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