Project description:The present work provides a multi-omics systems-wide view on S. rimosus. Using genomics, transcriptomics, proteomics, and metabolomics, we compared the wild type with an OTC-overproducing derivative, previously obtained by classical mutagenesis. The integration of the data provided a deep insight into the underlying metabolic and regulatory networks that mediate high-level OTC formation. Strikingly, the overproducer revealed a synergistically activated supply of acetyl-CoA and malonyl CoA and increased abundance of various CoA thioesters.
Project description:Ammonia production via glutamate dehydrogenase is inhibited by SIRT4, a sirtuin that displays both amidase and non-amidase activities. The processes underlying the regulation of ammonia removal by amino acids remain unclear. Here, we report that SIRT4 acts as a decarbamylase that responds to amino acid sufficiency and regulates ammonia removal. Amino acids promote lysine 307 carbamylation (OTCCP-K307) of ornithine transcarbamylase (OTC), which activates OTC and the urea cycle. Proteomic and interactome screening identified OTC as a substrate of SIRT4. SIRT4 decarbamylates OTCCP-K307 and inactivates OTC in a NAD+-dependent manner. SIRT4 expression was transcriptionally upregulated by the amino acid insufficiency-activated GCN2–eIF2a–ATF4 axis. SIRT4 knockout in cultured cells caused higher OTCCP-K307 levels, activated OTC, elevated urea cycle intermediates, and urea production via amino acid catabolism. Sirt4 ablation decreased mouse blood ammonia levels and ameliorated CCl4-induced hepatic encephalopathy phenotypes. We reveal that SIRT4 safeguards cellular ammonia toxicity during amino acid catabolism.
Project description:The present work provides a multi-omics systems-wide view on S. rimosus. Using genomics, transcriptomics, proteomics, and metabolomics, we compared the wild type with an OTC-overproducing derivative, previously obtained by classical mutagenesis. The integration of the data provided a deep insight into the underlying metabolic and regulatory networks that mediate high-level OTC formation. Strikingly, the overproducer revealed a synergistically activated supply of acetyl-CoA and malonyl CoA and increased abundance of various CoA thioesters.
Project description:Global warming is strongly affecting the Maritime Antarctica climate and the consequent melting of perennial snow and ice covers resulted in increased colonization by plants. Colobanthus quitensis is a vascular plant highly adapted to the harsh environmental conditions of Antarctic Peninsula and understanding how the plant is responding to global warming is a new challenging target for modern cell physiology. To this aim, we performed differential proteomic analysis on C. quitensis plants grown in natural conditions compared to plants grown for one year inside Open Top Chambers (OTCs) which determine an increase of about 4 °C at midday, mimicking the effect of global warming. A thorough analysis of the up- and down-regulated proteins highlighted an extensive metabolism reprogramming leading to the hypothesis that (i) photorespiration could play an important role in reducing ROS-mediated photodamage improving OTC plants protection against photoinhibition; (ii) OTC plants activate stronger antioxidant defenses as confirmed by enzymatic activity and TBARS content measurement; (iii) the deposition of cell wall components is impaired in OTC plants due to the down-regulation of many enzymes involved in their biosyn-thesis; (iv) OTC plants could suffer of a reduced freezing tolerance due to lower concentration of soluble sugars acting as osmoprotectants.