SnRK1 activation, signaling, and networking for energy homeostasis

The SnRK1 kinases are key regulators of the plant energy balance, but how their activity is regulated by metabolic status is still unclear. While the heterotrimeric kinase complex is well conserved between plants, fungi and animals, plants appear to have modified its regulation to better fit their unique physiology and lifestyle. The SnRK1 kinases control metabolism, growth and development, and stress tolerance by direct phosphorylation of metabolic enzymes and regulatory proteins and by extensive transcriptional regulation. Diverse types of transcription factors have already been implicated, with a well-studied role for the heterodimerizing group C and group S1 bZIPs. SnRK1 is also part of a more elaborate metabolic and stress signaling network, which includes the TOR kinase and the ABA-signaling SnRK2 kinases.status: Published onlin

Metabolic pathway engineering in Cupriavidus necator as platform for biofuel and chemicals production from CO2.

International audienc

Pectoral I Block Does Not Improve Postoperative Analgesia After Breast Cancer Surgery: A Randomized, Double-Blind, Dual-Centered Controlled Trial.

International audienceBACKGROUND AND OBJECTIVES:General anesthesia for breast surgery may be supplemented by using a regional anesthetic technique. We evaluated the efficacy of the first pectoral nerve block (Pecs I) in treating postoperative pain after breast cancer surgery.METHODS:A randomized, double-blind, dual-centered, placebo-controlled trial was performed. One hundred twenty-eight patients scheduled for unilateral breast cancer surgery were recruited. A multimodal analgesic regimen and surgeon-administered local anesthetic infiltration were used for all patients. Ultrasound-guided Pecs I was performed using bupivacaine or saline. The primary outcome was the patient pain score (numerical rating scale [NRS]) in the recovery unit 30 minutes after admission or just before the morphine administration (NRS ≥4/10). The secondary outcomes were postoperative opioid consumption (ie, in the recovery unit and after 24 hours).RESULTS:During recovery, no significant difference in NRS was observed between the bupivacaine (n = 62, 3.0 [1.0-4.0]) and placebo (n = 65, 3.0 [1.0-5.0]) groups (P = 0.55). However, the NRS was statistically significantly different, although not clinically significant, for patients undergoing major surgeries (mastectomies or tumorectomies with axillary clearance) (n = 29, 3.0 [0.0-4.0] vs 4.0 [2.0-5.0], P = 0.04). Morphine consumption during recovery did not differ (1.5 mg [0.0-6.0 mg] vs 3.0 mg [0.0-6.0 mg], P = 0.20), except in the major surgery subgroup (1.5 mg [0.0-6.0 mg] vs 6.0 mg [0.0-12.0 mg], P = 0.016). Intraoperative sufentanil and cumulative morphine consumption up to 24 hours did not differ between the 2 groups. Three patients experienced complications related to the Pecs I.CONCLUSIONS:Pecs I is not better than a saline placebo in the presence of multimodal analgesia for breast cancer surgery. However, its role in extended (major) breast surgery may warrant further investigation

Impaired KIN10 function restores developmental defects in the Arabidopsis trehalose 6-phosphate synthase1 (tps1) mutant

Sensing carbohydrate availability is essential for plants to coordinate their growth and development. In Arabidopsis thaliana, TREHALOSE 6-PHOSPHATE SYNTHASE 1 (TPS1) and its product, trehalose 6-phosphate (T6P), are important for the metabolic control of development. tps1 mutants are embryo-lethal and unable to flower when embryogenesis is rescued. T6P regulates development in part through inhibition of SUCROSE NON-FERMENTING1 RELATED KINASE1 (SnRK1). Here, we explored the role of SnRK1 in T6P-mediated plant growth and development using a combination of a mutant suppressor screen and genetic, cellular and transcriptomic approaches. We report nonsynonymous amino acid substitutions in the catalytic KIN10 and regulatory SNF4 subunits of SnRK1 that can restore both embryogenesis and flowering of tps1 mutant plants. The identified SNF4 point mutations disrupt the interaction with the catalytic subunit KIN10. Contrary to the common view that the two A. thaliana SnRK1 catalytic subunits act redundantly, we found that loss-of-function mutations in KIN11 are unable to restore embryogenesis and flowering, highlighting the important role of KIN10 in T6P signalling

A nitrogen-specific interactome analysis sheds light on the role of the SnRK1 and TOR kinases in plant nitrogen signaling

Nitrogen (N) is of utmost importance for plant growth and development. Multiple studies have shown that N signaling is tightly coupled with carbon (C) levels, but the interplay between C/N metabolism and growth remains largely an enigma. Nonetheless, the protein kinases Sucrose Non-fermenting 1 (SNF1)-Related Kinase 1 (SnRK1) and Target Of Rapamycin (TOR), two ancient central metabolic regulators, are emerging as key integrators that link C/N status with growth. Despite their pivotal importance, the exact mechanisms behind the sensing of N status and its integration with C availability to drive metabolic decisions are largely unknown. Especially for SnRK1 it is not clear how this kinase responds to altered N levels. Therefore, we first monitored N-dependent SnRK1 kinase activity with an in vivo Separation of Phase-based Activity Reporter of Kinase (SPARK) sensor, revealing a contrasting N-dependency in Arabidopsis thaliana (Arabidopsis) shoot and root tissues. Next, using affinity purification (AP) and proximity labeling (PL) coupled to mass spectrometry (MS) experiments, we constructed a comprehensive SnRK1 and TOR interactome in Arabidopsis cell cultures during N-starved and N-repleted growth conditions. To broaden our understanding of the N-specificity of the TOR/SnRK1 signaling events, the resulting network was compared to corresponding C-related networks, identifying a large number of novel, N-specific interactors. Moreover, through integration of N-dependent transcriptome and phosphoproteome data, we were able to pinpoint additional N-dependent network components, highlighting for instance SnRK1 regulatory proteins that might function at the crosstalk of C/N signaling. Finally, confirmation of known and identification of novel SnRK1 interactors, such as Inositol-Requiring 1 (IRE1A) and the RAB GTPase RAB18, indicate that SnRK1, present at the ER, is involved in N signaling and autophagy induction

Pluridisciplinary research on a woolly rhinoceros skeleton, Coelodonta antiquitatis (Blumenbach, 1799), from the Institut de paleontologie humaine (Paris, France)

<p>In 2010, the foundation Institut de paleontologie humaine (Paris) acquired an assembled skeleton of woolly rhinoceros, Coelodonta antiquitatis (Blumenbach, 1799). Its exceptional state of preservation allowed a multidisciplinary study: anatomical, biometrical, geochronological (AMS radiocarbon dating on horn and some bones) and biogeochemical analyses (reconstruction of the palaeodiet and the palaeoenvironment using the method of carbon and nitrogen isotopes). A research about the origin of this specimen and its story before its acquisition was also carried out. These different investigations led us to precise the species identification of this Siberian fossil, its biological age and its gender, as well as its chronological attribution and its dietary behavior. (c) 2013 Elsevier Masson SAS. All rights reserved.</p>

Mapping of the plant SnRK1 kinase signalling network reveals a key regulatory role for the class II T6P synthase-like proteins

The central metabolic regulator SnRK1 controls plant growth and survival upon activation by energy depletion, but detailed molecular insight into its regulation and downstream targets is limited. Here we used phosphoproteomics to infer the sucrose-dependent processes targeted upon starvation by kinases as SnRK1, corroborating the relation of SnRK1 with metabolic enzymes and transcriptional regulators, while also pointing to SnRK1 control of intracellular trafficking. Next, we integrated affinity purification, proximity labelling and crosslinking mass spectrometry to map the protein interaction landscape, composition and structure of the SnRK1 heterotrimer, providing insight in its plant-specific regulation. At the intersection of this multi-dimensional interactome, we discovered a strong association of SnRK1 with class II T6P synthase (TPS)-like proteins. Biochemical and cellular assays show that TPS-like proteins function as negative regulators of SnRK1. Next to stable interactions with the TPS-like proteins, similar intricate connections were found with known regulators, suggesting that plants utilize an extended kinase complex to fine-tune SnRK1 activity for optimal responses to metabolic stress

6-Phosphofructo-2-kinase and fructose-2,6-bisphosphatase in Trypanosomatidae. Molecular characterization, database searches, modelling studies and evolutionary analysis.

Fructose 2,6-bisphosphate is a potent allosteric activator of trypanosomatid pyruvate kinase and thus represents an important regulator of energy metabolism in these protozoan parasites. A 6-phosphofructo-2-kinase, responsible for the synthesis of this regulator, was highly purified from the bloodstream form of Trypanosoma brucei and kinetically characterized. By searching trypanosomatid genome databases, four genes encoding proteins homologous to the mammalian bifunctional enzyme 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase (PFK-2/FBPase-2) were found for both T. brucei and the related parasite Leishmania major and four pairs in Trypanosoma cruzi. These genes were predicted to each encode a protein in which, at most, only a single domain would be active. Two of the T. brucei proteins showed most conservation in the PFK-2 domain, although one of them was predicted to be inactive due to substitution of residues responsible for ligating the catalytically essential divalent metal cation; the two other proteins were most conserved in the FBPase-2 domain. The two PFK-2-like proteins were expressed in Escherichia coli. Indeed, the first displayed PFK-2 activity with similar kinetic properties to that of the enzyme purified from T. brucei, whereas no activity was found for the second. Interestingly, several of the predicted trypanosomatid PFK-2/FBPase-2 proteins have long N-terminal extensions. The N-terminal domains of the two polypeptides with most similarity to mammalian PFK-2s contain a series of tandem repeat ankyrin motifs. In other proteins such motifs are known to mediate protein-protein interactions. Phylogenetic analysis suggests that the four different PFK-2/FBPase-2 isoenzymes found in Trypanosoma and Leishmania evolved from a single ancestral bifunctional enzyme within the trypanosomatid lineage. A possible explanation for the evolution of multiple monofunctional enzymes and for the presence of the ankyrin-motif repeats in the PFK-2 isoenzymes is presented