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 language | English (US) |
|---|---|
| Pages (from-to) | 4752-4766 |
| Number of pages | 15 |
| Journal | Journal of Biological Chemistry |
| Volume | 293 |
| Issue number | 13 |
| DOIs | |
| State | Published - Jan 1 2018 |
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All Science Journal Classification (ASJC) codes
- Biochemistry
- Molecular Biology
- Cell Biology
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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 V.; 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 journal › Article
TY - JOUR
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 V.
AU - Torres, Matthew P.
AU - Jones, Alan M.
PY - 2018/1/1
Y1 - 2018/1/1
N2 - 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.”.
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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UR - http://www.scopus.com/inward/citedby.url?scp=85044975482&partnerID=8YFLogxK
U2 - 10.1074/jbc.RA117.000163
DO - 10.1074/jbc.RA117.000163
M3 - Article
C2 - 29382719
AN - SCOPUS:85044975482
VL - 293
SP - 4752
EP - 4766
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
SN - 0021-9258
IS - 13
ER -