Tyrosine phosphorylation switching of a G protein

Bo Li, Meral Tunc-Ozdemir, Daisuke Urano, Haiyan Jia, Emily G. Werth, David D. Mowrey, Leslie M. Hicks, Nikolay Dokholyan, Matthew P. Torres, Alan M. Jones

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

Heterotrimeric G protein complexes are molecular switches relaying extracellular signals sensed by G protein-coupled receptors (GPCRs) to downstream targets in the cytoplasm, which effect cellular responses. In the plant heterotrimeric GTPase cycle, GTP hydrolysis, rather than nucleotide exchange, is the rate-limiting reaction and is accelerated by a receptor-like regulator of G signaling (RGS) protein. We hypothesized that post-translational modification of the G subunit in the G protein complex regulates the RGS-dependent GTPase cycle. Our structural analyses identified an invariant phosphorylated tyrosine residue (Tyr 166 in the Arabidopsis G subunit AtGPA1) located in the intramolecular domain interface where nucleotide binding and hydrolysis occur. We also identified a receptor-like kinase that phosphorylates AtGPA1 in a Tyr 166 -dependent manner. Discrete molecular dynamics simulations predicted that phosphorylated Tyr 166 forms a salt bridge in this interface and potentially affects the RGS protein-accelerated GTPase cycle. Using a Tyr 166 phosphomimetic substitution, we found that the cognate RGS protein binds more tightly to the GDP-bound G substrate, consequently reducing its ability to accelerate GTPase activity. In conclusion, we propose that phosphorylation of Tyr 166 in AtGPA1 changes the binding pattern with AtRGS1 and thereby attenuates the steady-state rate of the GTPase cycle. We coin this newly identified mechanism “substrate phosphoswitching.”.

Original languageEnglish (US)
Pages (from-to)4752-4766
Number of pages15
JournalJournal of Biological Chemistry
Volume293
Issue number13
DOIs
StatePublished - Jan 1 2018

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Phosphorylation
GTP Phosphohydrolases
GTP-Binding Proteins
Tyrosine
GTP-Binding Protein Regulators
Hydrolysis
Nucleotides
Switch Genes
Heterotrimeric GTP-Binding Proteins
Numismatics
Molecular Dynamics Simulation
Post Translational Protein Processing
G-Protein-Coupled Receptors
Guanosine Triphosphate
Arabidopsis
Molecular dynamics
Cytoplasm
Substitution reactions
Phosphotransferases
Salts

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Molecular Biology
  • Cell Biology

Cite this

Li, B., Tunc-Ozdemir, M., Urano, D., Jia, H., Werth, E. G., Mowrey, D. D., ... Jones, A. M. (2018). Tyrosine phosphorylation switching of a G protein. Journal of Biological Chemistry, 293(13), 4752-4766. https://doi.org/10.1074/jbc.RA117.000163
Li, Bo ; Tunc-Ozdemir, Meral ; Urano, Daisuke ; Jia, Haiyan ; Werth, Emily G. ; Mowrey, David D. ; Hicks, Leslie M. ; Dokholyan, Nikolay ; Torres, Matthew P. ; Jones, Alan M. / Tyrosine phosphorylation switching of a G protein. In: Journal of Biological Chemistry. 2018 ; Vol. 293, No. 13. pp. 4752-4766.
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Li, B, Tunc-Ozdemir, M, Urano, D, Jia, H, Werth, EG, Mowrey, DD, Hicks, LM, Dokholyan, N, Torres, MP & Jones, AM 2018, 'Tyrosine phosphorylation switching of a G protein', Journal of Biological Chemistry, vol. 293, no. 13, pp. 4752-4766. https://doi.org/10.1074/jbc.RA117.000163

Tyrosine phosphorylation switching of a G protein. / Li, Bo; Tunc-Ozdemir, Meral; Urano, Daisuke; Jia, Haiyan; Werth, Emily G.; Mowrey, David D.; Hicks, Leslie M.; Dokholyan, Nikolay; Torres, Matthew P.; Jones, Alan M.

In: Journal of Biological Chemistry, Vol. 293, No. 13, 01.01.2018, p. 4752-4766.

Research output: Contribution to journalArticle

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T1 - Tyrosine phosphorylation switching of a G protein

AU - Li, Bo

AU - Tunc-Ozdemir, Meral

AU - Urano, Daisuke

AU - Jia, Haiyan

AU - Werth, Emily G.

AU - Mowrey, David D.

AU - Hicks, Leslie M.

AU - Dokholyan, Nikolay

AU - Torres, Matthew P.

AU - Jones, Alan M.

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AB - Heterotrimeric G protein complexes are molecular switches relaying extracellular signals sensed by G protein-coupled receptors (GPCRs) to downstream targets in the cytoplasm, which effect cellular responses. In the plant heterotrimeric GTPase cycle, GTP hydrolysis, rather than nucleotide exchange, is the rate-limiting reaction and is accelerated by a receptor-like regulator of G signaling (RGS) protein. We hypothesized that post-translational modification of the G subunit in the G protein complex regulates the RGS-dependent GTPase cycle. Our structural analyses identified an invariant phosphorylated tyrosine residue (Tyr 166 in the Arabidopsis G subunit AtGPA1) located in the intramolecular domain interface where nucleotide binding and hydrolysis occur. We also identified a receptor-like kinase that phosphorylates AtGPA1 in a Tyr 166 -dependent manner. Discrete molecular dynamics simulations predicted that phosphorylated Tyr 166 forms a salt bridge in this interface and potentially affects the RGS protein-accelerated GTPase cycle. Using a Tyr 166 phosphomimetic substitution, we found that the cognate RGS protein binds more tightly to the GDP-bound G substrate, consequently reducing its ability to accelerate GTPase activity. In conclusion, we propose that phosphorylation of Tyr 166 in AtGPA1 changes the binding pattern with AtRGS1 and thereby attenuates the steady-state rate of the GTPase cycle. We coin this newly identified mechanism “substrate phosphoswitching.”.

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Li B, Tunc-Ozdemir M, Urano D, Jia H, Werth EG, Mowrey DD et al. Tyrosine phosphorylation switching of a G protein. Journal of Biological Chemistry. 2018 Jan 1;293(13):4752-4766. https://doi.org/10.1074/jbc.RA117.000163