In most metazoans, different heterotrimeric G protein complexes couple many different upstream signals to different downstream effectors such as adenyl cyclase, ion channels, and phospholipases. However, in Arabidopsis, there is only a single canonical heterotrimeric G protein complex that nonetheless controls different plant responses. We do not know how this is accomplished nor do we know what receptors activate this G protein complex. Recent technical advances from my group using both gain- and loss-of-function approaches to understand the function of Arabidopsis G protein subunits will enable us to determine the molecular role of this G protein complex in various signaling pathways. There are three focus areas for this project: auxin control of root development, hypocotyl development; and multi-signal control of seed germination. Specifically, we will: 1. determine auxin responsiveness of G protein mutants and overexpressors and examine the signal cross-talk controlling seed germination, 2. identify and characterize genetic and physical interactors of Galpha and Gbeta using extragenic suppressor screens including activation mutagenesis and using cytosolic protein-protein interaction assays, and 3. test putative functions of a small set of candidate GPCRs using reverse genetic approaches. In summary, the goal is to test the hypothesis that auxin utilizes heterotrimeric G proteins in signal transduction. This work also addresses a longstanding problem on the mechanism of signal cross-talk. Because, the single Arabidopsis heterotrimeric G protein appears to be central to multiple signal pathways, genetic studies using Arabidopsis may reveal the core mechanism of signal integration, which is likely to be shared universally.

National Institute of Health (NIH)
National Institute of General Medical Sciences (NIGMS)
Research Project (R01)
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Genetics Study Section (GEN)
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Anderson, James J
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University of North Carolina Chapel Hill
Schools of Arts and Sciences
Chapel Hill
United States
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Song, Gaoyuan; Brachova, Libuse; Nikolau, Basil J et al. (2018) Heterotrimeric G-Protein-Dependent Proteome and Phosphoproteome in Unstimulated Arabidopsis Roots. Proteomics 18:e1800323
Li, Bo; Tunc-Ozdemir, Meral; Urano, Daisuke et al. (2018) Tyrosine phosphorylation switching of a G protein. J Biol Chem 293:4752-4766
Liao, Kang-Ling; Jones, Roger D; McCarter, Patrick et al. (2017) A shadow detector for photosynthesis efficiency. J Theor Biol 414:231-244
Tunc-Ozdemir, Meral; Li, Bo; Jaiswal, Dinesh K et al. (2017) Predicted Functional Implications of Phosphorylation of Regulator of G Protein Signaling Protein in Plants. Front Plant Sci 8:1456
Escudero, Viviana; Jordá, Lucía; Sopeña-Torres, Sara et al. (2017) Alteration of cell wall xylan acetylation triggers defense responses that counterbalance the immune deficiencies of plants impaired in the ?-subunit of the heterotrimeric G-protein. Plant J 92:386-399
Li, Bo; Makino, Shin-Ichi; Beebe, Emily T et al. (2016) Cell-free translation and purification of Arabidopsis thaliana regulator of G signaling 1 protein. Protein Expr Purif 126:33-41
Urano, Daisuke; Maruta, Natsumi; Trusov, Yuri et al. (2016) Saltational evolution of the heterotrimeric G protein signaling mechanisms in the plant kingdom. Sci Signal 9:ra93
Mudgil, Yashwanti; Karve, Abhijit; Teixeira, Paulo J P L et al. (2016) Photosynthate Regulation of the Root System Architecture Mediated by the Heterotrimeric G Protein Complex in Arabidopsis. Front Plant Sci 7:1255
Tunc-Ozdemir, Meral; Fu, Yan; Jones, Alan M (2016) Cautions in Measuring In Vivo Interactions Using FRET and BiFC in Nicotiana benthamiana. Methods Mol Biol 1363:155-74
Tunc-Ozdemir, Meral; Urano, Daisuke; Jaiswal, Dinesh Kumar et al. (2016) Direct Modulation of Heterotrimeric G Protein-coupled Signaling by a Receptor Kinase Complex. J Biol Chem 291:13918-25

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