The hormone auxin regulates virtually every aspect of plant growth and development. Genetic and molecular studies with Arabidopsis have defined the SCFTIR1 ubiquitin-ligase complex as a positive regulator of auxin response. Recent findings indicate that auxin promotes SCFTIR1-mediated ubiquitination of the Aux/IAA proteins, a large family of transcriptional regulators which negatively regulate auxin response. The subsequent proteasome-mediated degradation of the Aux/IAAs derepresses the auxin response pathway resulting in changes in growth and development. We have shown that Aux/IAA proteins physically interact with the SCFTIR1 complex in crude seedling extracts. Auxin promotes Aux/IAA degradation by targeting these factors to the SCFTIR1 ubiquitin-ligase by an undetermined mechanism. Elucidation of how auxin regulates this interaction will provide important information into the signaling events of the auxin response pathway upstream of the SCFTIR1 ubiquitin-ligase. The long-term goal of the proposed research is to understand the molecular mechanisms underlying auxin regulation of plant growth and development. The identification of the mechanisms underlying auxin action will provide new tools for modulating auxin response for agricultural and horticultural benefit. Further, since SCF-mediated ubiquitination is highly conserved, these studies will contribute toward our understanding of this mode of cellular regulation in all eukaryotes. The specific objectives of this proposal include; 1) elucidation of the nature and regulation of protein-protein interactions between the Aux/IAA transcriptional regulators and the SCFTIR1 ubiquitin-ligase complex; 2) the genetic and molecular analysis of a new class of Arabidopsis mutants defective in auxin response; 3) the molecular characterization of a mutant derivative of the AtCUL1 SCF subunit; and 4) investigate the biological significance of the interaction between the AXR2 Aux/IAA protein and the COP9 signalosome subunit CSN5.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM067203-02
Application #
6693316
Study Section
Cell Development and Function Integrated Review Group (CDF)
Program Officer
Anderson, James J
Project Start
2003-01-01
Project End
2009-08-31
Budget Start
2004-01-01
Budget End
2006-08-31
Support Year
2
Fiscal Year
2004
Total Cost
$224,877
Indirect Cost
Name
University of Minnesota Twin Cities
Department
Other Basic Sciences
Type
Schools of Arts and Sciences
DUNS #
555917996
City
Minneapolis
State
MN
Country
United States
Zip Code
55455
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Spartz, Angela K; Lor, Vai S; Ren, Hong et al. (2017) Constitutive Expression of Arabidopsis SMALL AUXIN UP RNA19 (SAUR19) in Tomato Confers Auxin-Independent Hypocotyl Elongation. Plant Physiol 173:1453-1462
Fan, Kai-Ting; Rendahl, Aaron K; Chen, Wen-Ping et al. (2016) Proteome Scale-Protein Turnover Analysis Using High Resolution Mass Spectrometric Data from Stable-Isotope Labeled Plants. J Proteome Res 15:851-67
Haruta, Miyoshi; Gray, William M; Sussman, Michael R (2015) Regulation of the plasma membrane proton pump (H(+)-ATPase) by phosphorylation. Curr Opin Plant Biol 28:68-75
Ren, Hong; Gray, William M (2015) SAUR Proteins as Effectors of Hormonal and Environmental Signals in Plant Growth. Mol Plant 8:1153-64
Jayaweera, Thilanka; Siriwardana, Chamindika; Dharmasiri, Sunethra et al. (2014) Alternative splicing of Arabidopsis IBR5 pre-mRNA generates two IBR5 isoforms with distinct and overlapping functions. PLoS One 9:e102301
Choi, Christina M; Gray, William M; Mooney, Sutton et al. (2014) Composition, roles, and regulation of cullin-based ubiquitin e3 ligases. Arabidopsis Book 12:e0175
Spartz, Angela K; Ren, Hong; Park, Mee Yeon et al. (2014) SAUR Inhibition of PP2C-D Phosphatases Activates Plasma Membrane H+-ATPases to Promote Cell Expansion in Arabidopsis. Plant Cell 26:2129-2142
Huang, He; Quint, Marcel; Gray, William M (2013) The eta7/csn3-3 auxin response mutant of Arabidopsis defines a novel function for the CSN3 subunit of the COP9 signalosome. PLoS One 8:e66578
Vi, Son Lang; Trost, Gerda; Lange, Peggy et al. (2013) Target specificity among canonical nuclear poly(A) polymerases in plants modulates organ growth and pathogen response. Proc Natl Acad Sci U S A 110:13994-9

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