Heterotrimeric G Protein γ Subunits Provide Functional Selectivity in Gßγ Dimer Signaling in Arabidopsis

Trusov, Yuri, Rookes, James Edward, Tilbrook, Kimberley, Chakravorty, David, Mason, Michael Glenn, Anderson, David, Chen, Jin-Gui, Jones, Alan M. and Botella, Jose Ramon (2007) Heterotrimeric G Protein γ Subunits Provide Functional Selectivity in Gßγ Dimer Signaling in Arabidopsis. Plant Cell, 19 4: 1235-1250. doi:10.1105/tpc.107.050096


Author Trusov, Yuri
Rookes, James Edward
Tilbrook, Kimberley
Chakravorty, David
Mason, Michael Glenn
Anderson, David
Chen, Jin-Gui
Jones, Alan M.
Botella, Jose Ramon
Title Heterotrimeric G Protein γ Subunits Provide Functional Selectivity in Gßγ Dimer Signaling in Arabidopsis
Journal name Plant Cell   Check publisher's open access policy
ISSN 1040-4651
Publication date 2007-01-01
Year available 2007
Sub-type Critical review of research, literature review, critical commentary
DOI 10.1105/tpc.107.050096
Open Access Status DOI
Volume 19
Issue 4
Start page 1235
End page 1250
Total pages 16
Place of publication Rockville, MD
Publisher American Society of Plant Biologists
Language eng
Subject C1
270400 Botany
620000 - Plant Production and Plant Primary Products
0601 Biochemistry and Cell Biology
Abstract The Arabidopsis thaliana heterotrimeric G protein complex is encoded by single canonical G alpha and G beta subunit genes and two G gamma subunit genes ( AGG1 and AGG2), raising the possibility that the two potential G protein complexes mediate different cellular processes. Mutants with reduced expression of one or both Gg genes revealed specialized roles for each Gg subunit. AGG1-deficient mutants, but not AGG2-deficient mutants, showed impaired resistance against necrotrophic pathogens, reduced induction of the plant defensin gene PDF1.2, and decreased sensitivity to methyl jasmonate. By contrast, both AGG1- and AGG2-deficient mutants were hypersensitive to auxin-mediated induction of lateral roots, suggesting that G beta gamma 1 and G beta gamma 2 synergistically inhibit auxin-dependent lateral root initiation. However, the involvement of each Gg subunit in this root response differs, with Gbg1 acting within the central cylinder, attenuating acropetally transported auxin signaling, while Gbg2 affects the action of basipetal auxin and graviresponsiveness within the epidermis and/or cortex. This selectivity also operates in the hypocotyl. Selectivity in G beta gamma signaling was also found in other known AGB1-mediated pathways. agg1 mutants were hypersensitive to glucose and the osmotic agent mannitol during seed germination, while agg2 mutants were only affected by glucose. We show that both G gamma subunits form functional G beta gamma dimers and that each provides functional selectivity to the plant heterotrimeric G proteins, revealing a mechanism underlying the complexity of G protein - mediated signaling in plants.
Formatted abstract
The Arabidopsis thaliana heterotrimeric G protein complex is encoded by single canonical Gα and Gβ subunit genes and two Gγ subunit genes ( AGG1 and AGG2), raising the possibility that the two potential G protein complexes mediate different cellular processes. Mutants with reduced expression of one or both Gγ genes revealed specialized roles for each Gγ subunit. AGG1-deficient mutants, but not AGG2-deficient mutants, showed impaired resistance against necrotrophic pathogens, reduced induction of the plant defensin gene PDF1.2, and decreased sensitivity to methyl jasmonate. By contrast, both AGG1- and AGG2-deficient mutants were hypersensitive to auxin-mediated induction of lateral roots, suggesting that Gβγ1 and Gβγ2 synergistically inhibit auxin-dependent lateral root initiation. However, the involvement of each Gγ subunit in this root response differs, with Gβγ1 acting within the central cylinder, attenuating acropetally transported auxin signaling, while Gβγ2 affects the action of basipetal auxin and graviresponsiveness within the epidermis and/or cortex. This selectivity also operates in the hypocotyl. Selectivity in Gβγ signaling was also found in other known AGB1-mediated pathways. agg1 mutants were hypersensitive to glucose and the osmotic agent mannitol during seed germination, while agg2 mutants were only affected by glucose. We show that both Gγ subunits form functional Gβγ dimers and that each provides functional selectivity to the plant heterotrimeric G proteins, revealing a mechanism underlying the complexity of G protein - mediated signaling in plants.
Keyword Biochemistry & Molecular Biology
Plant Sciences
Cell Biology
Lateral Root Initiation
Basipetal Auxin Transport
Alpha-subunit
Seed-germination
Plasma-membrane
Molecular-cloning
Phospholipase-c
Binding Protein
Cell-division
Alternaria-brassicicola
Q-Index Code C1
Q-Index Status Confirmed Code
Grant ID GM-65989-01
Institutional Status UQ
Additional Notes This document is a journal review.

Document type: Journal Article
Sub-type: Critical review of research, literature review, critical commentary
Collections: Excellence in Research Australia (ERA) - Collection
2008 Higher Education Research Data Collection
School of Biological Sciences Publications
 
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Created: Tue, 19 Feb 2008, 03:20:13 EST