Browsing by Author "Pandey, Sona"

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Conventional and novel Gγ protein families constitute the heterotrimeric G-protein signaling network in soybean
(Public Library of Science, 2011) Choudhury, Swarup Roy; Bisht, Naveen C.; Thompson, Rheannon; Todorov, Oleg; Pandey, Sona
Heterotrimeric G-proteins comprised of Gα, Gβ and Gγ proteins are important signal transducers in all eukaryotes. The Gγ protein of the G-protein heterotrimer is crucial for its proper targeting at the plasma membrane and correct functioning. Gγ proteins are significantly smaller and more diverse than the Gα and Gβ proteins. In model plants Arabidopsis and rice that have a single Gα and Gβ protein, the presence of two canonical Gγ proteins provide some diversity to the possible heterotrimeric combinations. Our recent analysis of the latest version of the soybean genome has identified ten Gγ proteins which belong to three distinct families based on their C-termini. We amplified the full length cDNAs, analyzed their detailed expression profile by quantitative PCR, assessed their localization and performed yeast-based interaction analysis to evaluate interaction specificity with different Gβ proteins. Our results show that ten Gγ genes are retained in the soybean genome and have interesting expression profiles across different developmental stages. Six of the newly identified proteins belong to two plant-specific Gγ protein families. Yeast-based interaction analyses predict some degree of interaction specificity between different Gβ and Gγ proteins. This research thus identifies a highly diverse G-protein network from a plant species. Homologs of these novel proteins have been previously identified as QTLs for grain size and yield in rice.
The small GTPase, nucleolar GTP-binding protein 1 (NOG1), has a novel role in plant innate immunity
(Nature Publishing Group, 2017) Lee, Seonghee; Senthil-Kumar, Muthappa; Kang, Miyoung; Rojas, Clemencia M.; Tang, Yuhong; Oh, Sunhee; Choudhury, Swarup Roy; Lee, Hee-Kyung; Ishiga, Yasuhiro; Allen, Randy D.; Pandey, Sona; Mysore, Kirankumar S.
Plant defense responses at stomata and apoplast are the most important early events during plant-bacteria interactions. The key components for the signaling of stomatal defense and nonhost resistance have not been fully characterized. Here we report the newly identified small GTPase, Nucleolar GTP-binding protein 1 (NOG1), functions for plant immunity against bacterial pathogens. Virus-induced gene silencing of NOG1 compromised nonhost resistance in N. benthamiana and tomato. Comparative genomic analysis showed that two NOG1 copies are present in all known plant species: NOG1-1 and NOG1-2. Gene downregulation and overexpression studies of NOG1-1 and NOG1-2 in Arabidopsis revealed the novel function of these genes in nonhost resistance and stomatal defense against bacterial pathogens, respectively. Specially, NOG1-2 regulates guard cell signaling in response to biotic and abiotic stimuli through jasmonic acid (JA)- and abscisic acid (ABA)-mediated pathways. The results here provide valuable information on the new functional role of small GTPase, NOG1, in guard cell signaling and early plant defense in response to bacterial pathogens.
Two chimeric regulators of G-protein signaling (RGS) proteins differentially modulate soybean heterotrimeric G-protein cycle
(The American Society for Biochemistry and Molecular Biology, 2012) Choudhury, Swarup Roy; Westfall, Corey S.; Laborde, John P.; Bisht, Naveen C.; Jez, Joseph M.; Pandey, Sona
Heterotrimeric G-proteins and the regulator of G-protein signaling (RGS) proteins, which accelerate the inherent GTPase activity of Gα proteins, are common in animals and encoded by large gene families; however, in plants G-protein signaling is thought to be more limited in scope. For example, Arabidopsis thaliana contains one Gα, one Gβ, three Gγ, and one RGS protein. Recent examination of the Glycine max (soybean) genome reveals a larger set of G-protein-related genes and raises the possibility of more intricate G-protein networks than previously observed in plants. Stopped-flow analysis of GTP-binding and GDP/GTP exchange for the four soybean Gα proteins (GmGα1-4) reveals differences in their kinetic properties. The soybean genome encodes two chimeric RGS proteins with an N-terminal seven transmembrane domain and a C-terminal RGS box. Both GmRGS interact with each of the four GmGα and regulate their GTPase activity. The GTPase-accelerating activities of GmRGS1 and -2 differ for each GmGα, suggesting more than one possible rate of the G-protein cycle initiated by each of the Gα proteins. The differential effects of GmRGS1 and GmRGS2 on GmGα1-4 result from a single valine versus alanine difference. The emerging picture suggests complex regulation of the G-protein cycle in soybean and in other plants with expanded G-protein networks.