TY - JOUR
T1 - Nucleotide exchange–dependent and nucleotide exchange–independent functions of plant heterotrimeric GTP-binding proteins
AU - Maruta, Natsumi
AU - Trusov, Yuri
AU - Chakravorty, David
AU - Urano, Daisuke
AU - Assmann, Sarah M.
AU - Botella, Jose R.
N1 - Funding Information:
We thank D. Greenway (University of Queensland) for providing an independent confirmation that appropriate statistical tests were used to analyze the data in this study. We thank A. M. Jones (University of North Carolina) for discussing our original data and hypothesis. We thank H. Okamoto (University of Southampton, United Kingdom) for providing the AtGPA1(Q222L) clone. The research was supported by the University of Queensland PhD scholarship (to N.M.) and by the National Institute of General Medical Sciences of the NIH under award number R01GM126079 (to S.M.A.). The content is solely the responsibility of the authors and does not necessarily represent the official views of the NIH.
Publisher Copyright:
Copyright © 2019 The Authors,
PY - 2019/11/5
Y1 - 2019/11/5
N2 - Heterotrimeric guanine nucleotide–binding proteins (G proteins), which are composed of α, β, and γ subunits, are versatile, guanine nucleotide–dependent, molecular on-off switches. In animals and fungi, the exchange of GDP for GTP on Gα controls G protein activation and is crucial for normal cellular responses to diverse extracellular signals. The model plant Arabidopsis thaliana has a single canonical Gα subunit, AtGPA1. We found that, in planta, the constitutively active, GTP-bound AtGPA1(Q222L) mutant and the nucleotide-free AtGPA1(S52C) mutant interacted with Gβγ1 and Gβγ2 dimers with similar affinities, suggesting that G protein heterotrimer formation occurred independently of nucleotide exchange. In contrast, AtGPA1(Q222L) had a greater affinity than that of AtGPA1(S52C) for Gβγ3, suggesting that the GTP-bound conformation of AtGPA1(Q222L) is distinct and tightly associated with Gβγ3. Functional analysis of transgenic lines expressing either AtGPA1(S52C) or AtGPA1(Q222L) in the gpa1-null mutant background revealed various mutant phenotypes that were complemented by either AtGPA1(S52C) or AtGPA1(Q222L). We conclude that, in addition to the canonical GDP-GTP exchange–dependent mechanism, plant G proteins can function independently of nucleotide exchange.
AB - Heterotrimeric guanine nucleotide–binding proteins (G proteins), which are composed of α, β, and γ subunits, are versatile, guanine nucleotide–dependent, molecular on-off switches. In animals and fungi, the exchange of GDP for GTP on Gα controls G protein activation and is crucial for normal cellular responses to diverse extracellular signals. The model plant Arabidopsis thaliana has a single canonical Gα subunit, AtGPA1. We found that, in planta, the constitutively active, GTP-bound AtGPA1(Q222L) mutant and the nucleotide-free AtGPA1(S52C) mutant interacted with Gβγ1 and Gβγ2 dimers with similar affinities, suggesting that G protein heterotrimer formation occurred independently of nucleotide exchange. In contrast, AtGPA1(Q222L) had a greater affinity than that of AtGPA1(S52C) for Gβγ3, suggesting that the GTP-bound conformation of AtGPA1(Q222L) is distinct and tightly associated with Gβγ3. Functional analysis of transgenic lines expressing either AtGPA1(S52C) or AtGPA1(Q222L) in the gpa1-null mutant background revealed various mutant phenotypes that were complemented by either AtGPA1(S52C) or AtGPA1(Q222L). We conclude that, in addition to the canonical GDP-GTP exchange–dependent mechanism, plant G proteins can function independently of nucleotide exchange.
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U2 - 10.1126/scisignal.aav9526
DO - 10.1126/scisignal.aav9526
M3 - Article
C2 - 31690635
AN - SCOPUS:85074576793
VL - 12
JO - Science's STKE : signal transduction knowledge environment
JF - Science's STKE : signal transduction knowledge environment
SN - 1937-9145
IS - 606
M1 - eaav9526
ER -