The overall goal of our research is to gain a molecular understanding of the regulatory processes that control the assimilation of inorganic nitrogen in plants. This process plays a central role in the regulation of plant growth and development. Using molecular-genetic approaches in Arabidopsis, we identified isoenzymes of GS, GOGAT and GDH that control the assimilation of inorganic-N into Glu/Gln, key amino acids used to transport nitrogen within and between cells. Our studies indicate that expression of these genes is regulated by the metabolic status of the plant. For example, transcriptional induction of GS by light, can be mimicked by sucrose in the absence of light. Moreover, sucrose induction of GS expression can be antagonized by amino acids, which results in repression of GS activity. This led us to hypothesize that plants have a mechanism to sense internal levels of amino acids. This would allow a plant to turn off assimilation of inorganic-N when internal levels of amino acid are high. Testing this hypothesis, defining it mechanistically, and identifying components thereof, is the focus of this renewal. Towards this goal, we have begun to characterize amino acid sensing/signaling components in Arabidopsis using molecular-genetic, cell biological, and biochemical approaches. Our reverse genetic studies are driven by the hypothesis that amino acid sensing is primitive and conserved in evolution. In support of this, the repression of GS expression by amino acids in plants is mechanistically reminiscent of the Ntr system in E. coli. Moreover, we identified a plant homologue of an Ntr component, PII, and showed using PII transgenic plants that PII appears to play a role in C:N sensing in chloroplasts an in GS regulation, as it does in Ntr. The amino acid products of N-assimilation are exported from chloroplasts and transported to other cells, and we have evidence that Glu, the prinicple intermediate, may serve as an extracellular signal . In support of this, we identified putative sensors of extracellular Glu, plant homologues of animal glutamate receptors (iGluRs). We showed plant GluRs function as ligand-gated ion channels, and studies of GLR transgenic plants indicate they may play a role in light signal transduction, reminiscent of their counterparts in the retina and brain. These findings suggest iGluRs are derived from a primitive amino acid signaling mechanism that existed before plants and animals diverged. We propose to exploit this evolutionary conservation and test whether Arabidopsis (or GLR mutants we isolate) can be used in a bioassay for drugs to treat GluR-related diseases in humans. We will also use forward genetic approaches to isolate amino acid sensing/signaling mutants in Arabidopsis which may identify components of these evolutionarily conserved amino acid signaling pathways or novel pathways.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
3R01GM032877-19S1
Application #
6650430
Study Section
Cell Development and Function Integrated Review Group (CDF)
Program Officer
Anderson, James J
Project Start
1983-12-01
Project End
2004-02-29
Budget Start
2002-03-01
Budget End
2003-02-28
Support Year
19
Fiscal Year
2002
Total Cost
$106,220
Indirect Cost
Name
New York University
Department
Biology
Type
Schools of Arts and Sciences
DUNS #
004514360
City
New York
State
NY
Country
United States
Zip Code
10012
Para, Alessia; Li, Ying; Coruzzi, Gloria M (2018) ?ChIP-Seq for Genome-Wide Mapping of In Vivo TF-DNA Interactions in Arabidopsis Root Protoplasts. Methods Mol Biol 1761:249-261
Gligorijevic, Vladimir; Barot, Meet; Bonneau, Richard (2018) deepNF: deep network fusion for protein function prediction. Bioinformatics 34:3873-3881
Tipton, Laura; Müller, Christian L; Kurtz, Zachary D et al. (2018) Fungi stabilize connectivity in the lung and skin microbial ecosystems. Microbiome 6:12
Varala, Kranthi; Marshall-Colón, Amy; Cirrone, Jacopo et al. (2018) Temporal transcriptional logic of dynamic regulatory networks underlying nitrogen signaling and use in plants. Proc Natl Acad Sci U S A 115:6494-6499
Swift, Joseph; Coruzzi, Gloria M (2017) A matter of time - How transient transcription factor interactions create dynamic gene regulatory networks. Biochim Biophys Acta Gene Regul Mech 1860:75-83
Baugh, Evan H; Simmons-Edler, Riley; Müller, Christian L et al. (2016) Robust classification of protein variation using structural modelling and large-scale data integration. Nucleic Acids Res 44:2501-13
Ristova, Daniela; Carré, Clément; Pervent, Marjorie et al. (2016) Combinatorial interaction network of transcriptomic and phenotypic responses to nitrogen and hormones in the Arabidopsis thaliana root. Sci Signal 9:rs13
Raviram, Ramya; Rocha, Pedro P; Müller, Christian L et al. (2016) 4C-ker: A Method to Reproducibly Identify Genome-Wide Interactions Captured by 4C-Seq Experiments. PLoS Comput Biol 12:e1004780
Doidy, Joan; Li, Ying; Neymotin, Benjamin et al. (2016) ""Hit-and-Run"" transcription: de novo transcription initiated by a transient bZIP1 ""hit"" persists after the ""run"". BMC Genomics 17:92
Varala, Kranthi; Li, Ying; Marshall-Colón, Amy et al. (2015) ""Hit-and-Run"" leaves its mark: catalyst transcription factors and chromatin modification. Bioessays 37:851-6

Showing the most recent 10 out of 76 publications