PMID:23696092

Citation	'Kim, JH and Kim, WT (2013) The Arabidopsis RING E3 Ubiquitin Ligase AtAIRP3/LOG2 Participates in Positive Regulation of High Salt and Drought Stress Responses. Plant Physiol. '
Abstract	RING E3 ubiquitin (Ub) ligases have been implicated in cellular response to the stress hormone abscisic acid (ABA) as well as to environmental stresses in higher plants. Here, an atairp3 (Arabidopsis thaliana ABA insensitive RING protein 3) loss-of-function mutant line was isolated due to its hyposensitivity to ABA during its germination stage as compared to wild-type plants. AtAIRP3 contains a single C3HC4-type RING motif, a putative myristoylation site, and a DAR2 domain. Unexpectedly, AtAIRP3 was identified as LOG2 (Loss of GDU2), which was recently shown to participate in an amino acid export system via interaction with GDU1 (GLUTAMINE DUMPER1). Thus, AtAIRP3 was renamed as AtAIRP3/LOG2. Transcript levels of AtAIRP3/LOG2 were upregulated by drought, high salinity, and ABA, suggesting a role for this factor in abiotic stress responses. The atairp3/log2-2 knock-out mutant and 35S:AtAIRP3-RNAi knock-down transgenic plants displayed impaired ABA-mediated seed germination and stomata closure. Co-suppression and complementation studies further supported a positive role for AtAIRP3/LOG2 in ABA responses. Suppression of AtAIRP3/LOG2 resulted in marked hypersensitive phenotypes toward high salinity and water deficit relative to wild-type plants. These results suggest that Arabidopsis RING E3 AtAIRP3/LOG2 is a positive regulator of the ABA-mediated drought and salt stress tolerance mechanism. Using yeast two-hybrid, in vitro and in vivo immunoprecipitation, cell-free protein degradation, and in vitro ubiquitination assays, RD21 (Responsive to Dehydration 21) was identified as a substrate protein of AtAIRP3/LOG2. Collectively, our data suggest that AtAIRP3/LOG2 plays dual functions in ABA-mediated drought stress responses and in an amino acid export pathway in Arabidopsis.
Links	PubMed Online version:10.1104/pp.113.220103
Keywords
edit table

Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
ARATH:LOFG2		GO:1901527: abscisic acid mediated signaling pathway involved in stomatal movement	ECO:0000315:		P		Figure 3C shows that atairp3/log2-2 knockout and 35S:AtAIRP3-RNAi knockdown mutants exhibit impaired stomatal closure response to different concentrations of abscisic acid when compared to wild type. Figure 3D graphically quantifies this impaired response.	complete CACAO 8450
ARATH:LOFG2		GO:0009737: response to abscisic acid stimulus	ECO:0000315:		P		Figure 3A shows that atairp3/log2-2 knockout and 35S:AtAIRP3-RNAi knockdown mutants exhibit reduced ABA-mediated inhibition of germination. Figure 3B shows that atairp3/log2-2 mutants have a higher radical emergence percentage than wild type at different concentrations of abscisic acid, as well as substantially higher percentages of cotyledon greening.	complete CACAO 8451
ARATH:LOFG2	involved_in	GO:1901527: abscisic acid-activated signaling pathway involved in stomatal movement	ECO:0000315: mutant phenotype evidence used in manual assertion		P		Seeded From UniProt	complete
ARATH:LOFG2	involved_in	GO:0009737: response to abscisic acid	ECO:0000315: mutant phenotype evidence used in manual assertion		P		Seeded From UniProt	complete

References

See Help:References for how to manage references in GONUTS.