Gγ1+Gγ2+Gγ3=Gβ: The search for heterotrimeric G-protein γ subunits in Arabidopsis is over

Thung, Leena; Trusov, Yuri; Chakravorty, David; Botella, José Ramón

doi:10.1016/j.jplph.2011.11.010

Cited by 83 publications

(86 citation statements)

References 20 publications

(31 reference statements)

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“…Gg subtypes from N. benthamiana are yet to be characterized, and were also not included in the present analysis. However, phylogenetic analysis of three A. thaliana Gg subunits, including the recently characterized third Gg subunit (Thung et al, 2012), reveals that all three subunits, AGG1 (arabidopsis GTP binding protein gamma subunit), AGG2, and AGG3, share a common ancestor with the vertebrate Gg1/9/11 class. Since this common ancestor was the most divergent ancestral Gg from the initial Gg subunit, this suggests that Gg subunits have evolved to become highly specialized in A. thaliana.…”

Section: Plant Gbgmentioning

confidence: 99%

The Expanding Roles of GβγSubunits in G Protein–Coupled Receptor Signaling and Drug Action

et al. 2013

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Section: Plant Gbgmentioning

confidence: 99%

The Expanding Roles of GβγSubunits in G Protein–Coupled Receptor Signaling and Drug Action

et al. 2013

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“…In Arabidopsis thaliana (hereafter referred to as Arabidopsis), the heterotrimeric G protein complex consists of one canonical G␣ subunit (AtGPA1), one G␤ subunit (AGB1), and one of three G␥ subunits (AGG1, AGG2, and AGG3) (1). The canonical G␣ subunit AtGPA1 self-activates through spontaneous GDP/GTP exchange without G protein-coupled receptors (GPCRs) 2 (2).…”

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confidence: 99%

Direct Modulation of Heterotrimeric G Protein-coupled Signaling by a Receptor Kinase Complex

Tunc‐Ozdemir

Urano

Jaiswal

et al. 2016

Journal of Biological Chemistry

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Plants and some protists have heterotrimeric G protein complexes that activate spontaneously without canonical G proteincoupled receptors (GPCRs). In Arabidopsis, the sole 7-transmembrane regulator of G protein signaling 1 (AtRGS1) modulates the G protein complex by keeping it in the resting state (GDP-bound). However, it remains unknown how a myriad of biological responses is achieved with a single G protein modulator. We propose that in complete contrast to G protein activation in animals, plant leucine-rich repeat receptor-like kinases (LRR RLKs), not GPCRs, provide this discrimination through phosphorylation of AtRGS1 in a ligand-dependent manner. G protein signaling is directly activated by the pathogen-associated molecular pattern flagellin peptide 22 through its LRR RLK, FLS2, and co-receptor BAK1.

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“…Arabidopsis G proteins have been implicated in cell division Chen et al, 2006) and morphological development in various tissues, including hypocotyls (Ullah et al, , 2003, roots (Ullah et al, 2003;Chen et al, 2006;Li et al, 2012), leaves (Lease et al, 2001;Ullah et al, 2001), inflorescences (Ullah et al, 2003), and flowers and siliques (Lease et al, 2001), as well as in pathogen responses (Llorente et al, 2005;Trusov et al, 2006;Cheng et al, 2015), regulation of stomatal movement (Wang et al, 2001;Coursol et al, 2003;Fan et al, 2008) and development Nilson and Assmann, 2010), cell wall composition (Delgado-Cerezo et al, 2012), responses to various light stimuli (Warpeha et al, 2007;Botto et al, 2009), responses to multiple abiotic stimuli (Huang et al, 2006;Pandey et al, 2006;Trusov et al, 2007;Zhang et al, 2008;Colaneri et al, 2014), responses to various hormones during germination (Ullah et al, 2002), and postgermination development (Ullah et al, 2002;Pandey et al, 2006;Trusov et al, 2007). Since the Gg subunit appeared to be the only subunit that provides diversity in heterotrimer composition in Arabidopsis, it was proposed that all functional specificity in heterotrimeric G protein signaling was provided by the Gg subunit (Trusov et al, 2007;Chakravorty et al, 2011;Thung et al, 2012Thung et al, , 2013. This allowed for only three heterotrimer combinations to account for the wide range of G protein-associated phenotypes.…”

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confidence: 99%

Extra-Large G Proteins Expand the Repertoire of Subunits in Arabidopsis Heterotrimeric G Protein Signaling

et al. 2015

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Heterotrimeric G proteins, consisting of Ga, Gb, and Gg subunits, are a conserved signal transduction mechanism in eukaryotes. However, G protein subunit numbers in diploid plant genomes are greatly reduced as compared with animals and do not correlate with the diversity of functions and phenotypes in which heterotrimeric G proteins have been implicated. In addition to GPA1, the sole canonical Arabidopsis (Arabidopsis thaliana) Ga subunit, Arabidopsis has three related proteins: the extra-large GTP-binding proteins XLG1, XLG2, and XLG3. We demonstrate that the XLGs can bind Gbg dimers (AGB1 plus a Gg subunit: AGG1, AGG2, or AGG3) with differing specificity in yeast (Saccharomyces cerevisiae) three-hybrid assays. Our in silico structural analysis shows that XLG3 aligns closely to the crystal structure of GPA1, and XLG3 also competes with GPA1 for Gbg binding in yeast. We observed interaction of the XLGs with all three Gbg dimers at the plasma membrane in planta by bimolecular fluorescence complementation. Bioinformatic and localization studies identified and confirmed nuclear localization signals in XLG2 and XLG3 and a nuclear export signal in XLG3, which may facilitate intracellular shuttling. We found that tunicamycin, salt, and glucose hypersensitivity and increased stomatal density are agb1-specific phenotypes that are not observed in gpa1 mutants but are recapitulated in xlg mutants. Thus, XLG-Gbg heterotrimers provide additional signaling modalities for tuning plant G protein responses and increase the repertoire of G protein heterotrimer combinations from three to 12. The potential for signal partitioning and competition between the XLGs and GPA1 is a new paradigm for plant-specific cell signaling.

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Gγ1+Gγ2+Gγ3=Gβ: The search for heterotrimeric G-protein γ subunits in Arabidopsis is over

Cited by 83 publications

References 20 publications

The Expanding Roles of GβγSubunits in G Protein–Coupled Receptor Signaling and Drug Action

The Expanding Roles of GβγSubunits in G Protein–Coupled Receptor Signaling and Drug Action

Direct Modulation of Heterotrimeric G Protein-coupled Signaling by a Receptor Kinase Complex

Extra-Large G Proteins Expand the Repertoire of Subunits in Arabidopsis Heterotrimeric G Protein Signaling

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