A SnRK1-JMJ15-CRF6 coregulatory module gages mitochondrial functional status to mitigate growth-defense trade-off in Arabidopsis
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ABSTRACT: Mitochondrion is a signaling organelle sensing environmental changes and integrating cellular responses via retrograde signalling. However, it is still largely unknown how mitochondria help plants cope with adversity while it powers plant growth. In this work, we identify two new targets of plant SNF1-Related Kinase1 (SnRK1), namely histone H3K4me3 demethylase JMJ15 and transcription factor CRF6. We show that JMJ15 and CRF6 are required for reprograming transcription in response to Antimycin A (AA)-induced mitochondrial stress. A functional module of JMJ15 and CRF6 with SnRK1 that measures mitochondrial status is supported by the AA-promoted nuclear translocation of SnRK1a, a-subunit of SnRK1 under mitochondrial stress, and the physical interaction of SnRK1a with JMJ15 and CRF6, and high correlation of transcriptome changes resulted from the genetic inactivation of JMJ15 and CRF6 with the ones from the plant overexpressing SnRK1a under normal and AA stress conditions. We show that SnRK1a phosphorylates and destabilize JMJ15 to inhibit its H3K27me3 demethylase activity. While SnRK1a does not phosphorylated CRF6, it promotes CRF6 degradation via proteasome pathway. CRF6 interacts with JMJ15, and prevents JMJ15 from phosphorylation dependent degradation, offering a feedback loop to antagonize the action of SnRK1a. Our findings indicate a new mechanism in which a histone demethylase mediated epigenetic regulation and a transcription factor govern cytokine and oxidative stress signalling are implicated in SnRK1-integrated transcriptional network to mitigate growth-defense trade-offs under mitochondrial dysfunction.
Project description:Sucrose Non-Fermenting1-Related Kinase1 (SnRK1) is an evolutionarily conserved protein kinase with key functions in energy management during stress responses in plants. To address a potential role of SnRK1 under non-stress conditions, we performed a metabolomic and transcriptomic characterization of 20 d-old rosettes of Arabidopsis SnRK1 gain- and loss-of-function mutants during the diurnal cycle. SnRK1 manipulation altered the slope of the correlation between sucrose and trehalose 6-phosphate (Tre6P). It also modulated the flux of carbon to the tricarboxylic acid cycle downstream of Tre6P-signalling. SnRK1 depletion modified expression of SnRK1-induced genes least at the end of the day (when Tre6P levels peak) and most at the end of the night (when Tre6P levels are lowest). Expression of a subset of these genes was attenuated by inducible Tre6P accumulation in a time-of-day dependent manner. Finally, transcriptional profiling uncovered a wide impact of SnRK1 on gene expression in non-stress conditions, establishing a clear connection with iron and sulfur metabolism. In conclusion, SnRK1 plays central functions in metabolic and transcriptional regulation in the absence of stress. SnRK1 is further involved in the reciprocal control of sucrose-driven Tre6P production and/or degradation and its activity is modulated by daily fluctuations in Tre6P levels.
Project description:Coordinated metabolism of carbon and nitrogen is essential for optimal plant growth and development. Nitrate is an important molecular signal for plant adaptation to changing environmental conditions, but how nitrate regulates plant growth under carbon deficiency conditions remains unclear. Here, we show that the evolutionarily conserved energy sensor SnRK1 negatively regulates the nitrate signaling pathway. Nitrate promoted plant growth and downstream gene expression, but such effects were significantly repressed when plants were grown under carbon deficiency conditions. Mutation of KIN10, the α-catalytic subunit of SnRK1, partially suppressed the inhibitory effects of carbon deficiency on nitrate-mediated plant growth. KIN10 phosphorylated NLP7, the master regulator of nitrate signaling pathway, to promote its cytoplasmic localization and degradation. Furthermore, nitrate depletion induced KIN10 accumulation, whereas nitrate treatment promoted KIN10 degradation. Such KIN10-mediated NLP7 regulation allows carbon and nitrate availability to control the optimal nitrate signaling and ensures the coordination of carbon and nitrogen metabolism in plants.
Project description:The goal of this study is to compare translation regulation in Col-0, SnRK1, and eIFiso4G1 mutants in Arabidopsis under submergence
Project description:Sucrose non-fermenting-1-related protein kinase 1 (SnRK1) is a central regulator of metabolism and developmental transition in plant. Compound 991 is a well-known 5′-adenosine monophosphate activated protein kinase (AMPK) activator in mammals. SnRK1 and AMPK are highly conserved. However, whether 991 could also act as a SnRK1 activator is unknown. Adding 991 significantly increased the activity of SnRK1 in desalted extracts from germinating rice seeds in vitro. To determine whether 991 has biological activity in plant, rice seeds were treated with different concentrations of 991. Low concentration of 991 promoted rice seed germination, while high concentration of 991 inhibited rice germination. The effect of 991 on rice germination is similar to the effect of OsSnRK1a overexpression on germination. To explore whether 991 affects germination by specifically affecting SnRK1, the germination status of the snrk1a mutant and WT under 1 μM 991 treatment were compared. The snrk1a mutant exhibited insensitivity to 991. Through phosphoproteomic analysis, we found that the differential phosphopeptides caused by 991 treatments and overexpression of OsSnRK1a are largely overlapped. Phosphoproteomic analysis also revealed that SnRK1 might affect rice germination by regulating the phosphorylation levels of S285-PIP2;4, S1013-SOS1 and S110-ABI5. These results showed that 991 is a specific and workable SnRK1 activator in rice. The promotion and inhibition of 991 treatments on germination also exist in wheat seeds. 991 is expected to be used for exploring the function of SnRK1 in more detail and depth and chemical regulation of growth and development in crops.
Project description:The plant SNF1-related kinase (SnRK1) plays a central role in energy and metabolic homeostasis. SnRK1 controls growth upon activation by energy-depleting stress conditions, while also monitoring key developmental transitions and nutrient allocation between source and sink tissues. To obtain deeper insight into the SnRK1 complex and its upstream regulatory mechanisms, we explored its protein interaction landscape in a multi-dimensional setting, combining affinity purification, proximity labeling and crosslinking mass spectrometry. Integration of these analyses not only offers a unique view on the composition, stoichiometry and structure of the core heterotrimeric SnRK1 complex but also reveals a myriad of novel robust SnRK1 interactors.
Project description:The plant SNF1-related kinase (SnRK1) plays a central role in energy and metabolic homeostasis. SnRK1 controls growth upon activation by energy-depleting stress conditions, while also monitoring key developmental transitions and nutrient allocation between source and sink tissues. To obtain deeper insight into the SnRK1 complex and its upstream regulatory mechanisms, we explored its protein interaction landscape in a multi-dimensional setting, combining affinity purification, proximity labeling and crosslinking mass spectrometry. Integration of these analyses not only offers a unique view on the composition, stoichiometry and structure of the core heterotrimeric SnRK1 complex but also reveals a myriad of novel robust SnRK1 interactors.
Project description:Arabidopsis SnRK1 is structurally and functionally related to the yeast Snf1 and mammalian AMP-activated kinases, which are activated in response to carbon/glucose limitation and stress conditions causing an imbalance of energy homeostasis increasing the AMP/ATP ratio. Mutations of the SNF4 activating subunit of trimeric Arabidopsis SnRK1 complexes are not transmitted through the male meiosis. Silencing of SNF4 by a β-estradiol-inducible artificial microRNA (amiR-SNF4) constructs was used to examine how inhibition of SnRK1 affects transcriptional regulation of different cellular pathways in dark and light grown seedlings. This study shows that amiR-SNF4 silencing of SnRK1 leads to coordinate transcriptional activation of salicylic acid and trehalose synthesis, oxidative/endoplasmic reticulum stress and pathogen defense responses by inducing simultaneous changes in numerous other essential hormonal and metabolic pathways in Arabidopsis. We used Affymetrix ATH1-121501 Genome Array to compare global transcript levels in wild type and β-estradiol-induced amiR-SNF4 mutant seedlings 5 days after germination in the dark or light.
Project description:Insufficient leaf photosynthesis promotes sheath NSC transport to the panicle during grain filling. SnRK1 regulates assimilate distribution between plant tissues and organs. However, the mechanism by which SnRK1 regulates sheath NSC transport to the panicle and its response to limited leaf assimilation remain unclear. Here, we performed leaf cutting (LC) at anthesis to simulate insufficient leaf assimilation and set no treatment as a CK. In response to LC, SnRK1 activity increased rapidly, and NSC transport was advanced. Sheath NSCs were not transported in a snrk1a mutant with deficient SnRK1 activity. These results indicated that SnRK1 activity is important for sheath NSC transport. The high correlation of T6P and sucrose and the inhibition of SnRK1 by T6P in sheaths in vitro implied that T6P slightly inhibits SnRK1 activity in rice sheaths in response to sucrose availability. The increase in SnRK1 activity was accompanied by an increase in OsSnRK1a expression and a low sucrose content. Low sucrose signaling increases SnRK1 transcription. Therefore, we speculated that OsSnRK1a expression positively regulates SnRK1 activity in response to low sucrose availability in rice sheaths. Through phosphoproteomics and further PRM verification, 20 phosphosites that depend on SnRK1 and are correlated with NSC transport were obtained. Based on the function of these sites and proteins, we found that SnRK1 regulates starch degradation, sucrose metabolism, phloem transport, sugar transport across tonoplast, and glycolysis via phosphorylation to promote sheath NSC transport. Overall, our results revealed the importance, function and regulatory mechanism of SnRK1 in sheath NSC transport.
Project description:Insufficient leaf photosynthesis promotes sheath NSC transport to the panicle during grain filling. SnRK1 regulates assimilate distribution between plant tissues and organs. However, the mechanism by which SnRK1 regulates sheath NSC transport to the panicle and its response to limited leaf assimilation remain unclear. Here, we performed leaf cutting (LC) at anthesis to simulate insufficient leaf assimilation and set no treatment as a CK. In response to LC, SnRK1 activity increased rapidly, and NSC transport was advanced. Sheath NSCs were not transported in a snrk1a mutant with deficient SnRK1 activity. These results indicated that SnRK1 activity is important for sheath NSC transport. The high correlation of T6P and sucrose and the inhibition of SnRK1 by T6P in sheaths in vitro implied that T6P slightly inhibits SnRK1 activity in rice sheaths in response to sucrose availability. The increase in SnRK1 activity was accompanied by an increase in OsSnRK1a expression and a low sucrose content. Low sucrose signaling increases SnRK1 transcription. Therefore, we speculated that OsSnRK1a expression positively regulates SnRK1 activity in response to low sucrose availability in rice sheaths. Through phosphoproteomics and further PRM verification, 20 phosphosites that depend on SnRK1 and are correlated with NSC transport were obtained. Based on the function of these sites and proteins, we found that SnRK1 regulates starch degradation, sucrose metabolism, phloem transport, sugar transport across tonoplast, and glycolysis via phosphorylation to promote sheath NSC transport. Overall, our results revealed the importance, function and regulatory mechanism of SnRK1 in sheath NSC transport.
Project description:SnRK1 (sucrose-non-fermenting-1-related) protein kinases are involved in the regulation of plant metabolism controlling both gene expression and phosphorylation. The aim of the study was to investigate the role of SnRK1 in pea seed development. To study the effect of SnRK1 deficiency, transgenic pea plants were generated carrying a gene for VfSnRK1 in antisense orientation under control of seed specific vicilin promoter. Selected transgenic lines were characterized with decreased levels of PsSnRK1 mRNA and reduced up to 71% phosphorylation activity. Antisense inhibition of SnRK1 resulted in reduced seeds fresh weight, defect of pollen development. To dissect the SnRK1-antisense phenotype at the molecular level, a search for genes with differential expression patterns in transgenic plant versus wild type seeds has been performed using cDNA macroarray analysis. Radioactive labeled cDNA probes were prepared from RNA isolated from embryo of developing seeds of wild type (11, 13, 15, 17, 19, and 21 DAP) and transgenic SnRK1-antisense plant (13, 15, 17 and 19 DAP), which correspond to the transition phase of seed development, and hybridized to cDNA macroarrays.