Project description:We show that a custom-designed RNA-binding protein binds and specifically induces cleavage of atp1 RNA in mitochondria, significantly decreasing the abundance of the Atp1 protein and the assembled F1Fo ATP synthase in Arabidopsis thaliana. Changes to the proteome as a consequence of the modification were investigated by shotgun proteomics on enriched mitochondrial fractions.
Project description:Aiming at defining the protein content and composition of a single mitochondrion of Arabidopsis thaliana, shotgun analyses were performed on purified mitochondria from cultured heterotrophic Arabidopsis cells. Based on microscopic observations on the size of mitochondria, as well as biochemical properties, such as protein concentration, average molecular mass of proteins, and the average length of the signal peptide, intensity-based absolute quantification (iBAQ) values were applied to calculate the copy number of each identified protein species within a single mitochondrion. Copy numbers of the individual proteins span five orders of magnitude, ranging from >40,000 for Voltage-Dependent Anion Channel 1 (VDAC1) to sub-stoichiometric copy numbers, i.e. less than a single copy per single mitochondrion, for several pentatricopeptide repeat (PPR) proteins that modify mitochondrial transcripts. Aiming at defining the protein content and composition of a single mitochondrion of Arabidopsis thaliana, shotgun analyses were performed on purified mitochondria from cultured heterotrophic Arabidopsis cells. Based on microscopic observations on the size of mitochondria, as well as biochemical properties, such as protein concentration, average molecular mass of proteins, and the average length of the signal peptide, intensity-based absolute quantification (iBAQ) values were applied to calculate the copy number of each identified protein species within a single mitochondrion. Copy numbers of the individual proteins span five orders of magnitude, ranging from >40,000 for Voltage-Dependent Anion Channel 1 (VDAC1) to sub-stoichiometric copy numbers, i.e. less than a single copy per single mitochondrion, for several pentatricopeptide repeat (PPR) proteins that modify mitochondrial transcripts. Aiming at defining the protein content and composition of a single mitochondrion of Arabidopsis thaliana, shotgun analyses were performed on purified mitochondria from cultured heterotrophic Arabidopsis cells. Based on microscopic observations on the size of mitochondria, as well as biochemical properties, such as protein concentration, average molecular mass of proteins, and the average length of the signal peptide, intensity-based absolute quantification (iBAQ) values were applied to calculate the copy number of each identified protein species within a single mitochondrion. Copy numbers of the individual proteins span five orders of magnitude, ranging from >40,000 for Voltage-Dependent Anion Channel 1 (VDAC1) to sub-stoichiometric copy numbers, i.e. less than a single copy per single mitochondrion, for several pentatricopeptide repeat (PPR) proteins that modify mitochondrial transcripts.
Project description:Defects of mitochondrial functions lead in humans to vast array of usually multisystemic pathologies and several hundreds of diseases resulting from various defects of mitochondria biogenesis and maintenance, defects of respiratory chain complexes (OXPHOS) or defects of individual mitochondrial proteins are known. We used Agilent Whole Human Genome Microarray for gene expression profiling of genetically heterogeneous group of 13 patients with biochemically proven ATP synthase deficiency. Gene expression data analysis allowed classification of patients into several distinct groups, provided information on subgroup and patient specific gene expression profiles, defined candidate disease causing genes and gave basic information on pathogenic mechanisms associated with ATP synthase deficiency. Keywords: ATP synthase, mitochondrial biogenesis, ROS, gene expression, microarray, human Two-condition experiment, patients vs. controls cells. Biological replicates: 9 control, 13 patients, independently grown and harvested.
Project description:Mitochondrial DNA (mtDNA) encodes essential components of the respiratory chain and loss of mtDNA leads to mitochondrial dysfunction and neurodegeneration. Mitochondrial transcription factor A (TFAM) is an essential component of mtDNA replication and a regulator of mitochondrial copy number in cells. Studies have shown that TFAM knockdown leads to mitochondrial dysfunction and respiratory chain deficiencies. ATP synthase is Complex V of the mitochondrial respiratory chain. It is driven by a proton gradient between the intermembrane space and the mitochondrial matrix and generates the majority of cellular ATP. The knockdown of coupling factor 6 (Cf6), one of the components of the proton channel F0, causes dysfunction in the complex, leading to mitochondrial dysfunction and respiratory chain deficiencies. Using gene expression analysis, we aimed to investigate the effects of mtDNA dysfunction in the CNS at the molecular level.
Project description:Mitochondria are responsible for energy production through aerobic respiration and represent the powerhouse of eukaryotic cells. Their metabolism and gene expression processes combine bacterial-like features and traits that evolved in eukaryotes. Among mitochondrial gene expression processes, translation remains the most elusive. In plants, while numerous pentatricopeptide repeat (PPR) proteins are involved in all steps of gene expression, their function in translation remains unclear. Here we present the biochemical characterisation of Arabidopsis mitochondrial ribosomes and identify their protein subunit composition. Complementary biochemical approaches identify 19 plant specific mitoribosome proteins, among which 10 are PPR proteins. The knock out mutations of ribosomal PPR (rPPR) genes result in distinct macroscopic phenotypes including lethality or severe growth delays. The molecular analysis of rppr1 mutants using ribosome profiling as well as the analysis of mitochondrial protein levels reveal that rPPR1 is a generic translation factor, which is a novel function for PPR proteins. Finally, single particle cryo-electron microscopy reveals the unique structural architecture of Arabidopsis mitoribosomes, characterised by a very large small ribosomal subunit, larger than the large subunit, bearing an additional RNA domain grafted onto the head. Overall, our results show that Arabidopsis mitoribosomes are substantially divergent from bacterial and other eukaryote mitoribosomes, both in terms of structure and of protein content.
Project description:Reduction of mitochondrial membrane potential is a hallmark of mitochondrial dysfunction. It activates adaptive responses in organisms from yeast to human to rewire metabolism, remove depolarized mitochondria, and degrade unimported precursor proteins. It remains unclear how cells maintain mitochondrial membrane potential, which is critical for maintaining iron-sulfur cluster (ISC) synthesis, an indispensable function of mitochondria. Here we show that yeast oxidative phosphorylation mutants deficient in complex III, IV, V, and mtDNA respectively, have graded reduction of mitochondrial membrane potential and proliferation rates. Extensive omics analyses of these mutants show that accompanying mitochondrial membrane potential reduction, these mutants progressively activate adaptive responses, including transcriptional downregulation of ATP synthase inhibitor Inh1 and OXPHOS subunits, Puf3-mediated upregulation of import receptor Mia40 and global mitochondrial biogenesis, Snf1/AMPK-mediated upregulation of glycolysis and repression of ribosome biogenesis, and transcriptional upregulation of cytoplasmic chaperones. These adaptations disinhibit mitochondrial ATP hydrolysis, remodel mitochondrial proteome, and optimize ATP supply to mitochondria to convergently maintain mitochondrial membrane potential, ISC biosynthesis, and cell proliferation.
Project description:The goal of this analysis was to profile the gene expression signatures associated to different neuronal doses of IF1. The mitochondrial ATP synthase produces ATP by oxidative phosphorylation and integrates different signals to regulate cellular functions and fate. The ATPase inhibitory factor 1 (IF1) is a structurally-disordered protein that inhibits the ATP synthase, contributing to metabolic reprogramming and signalling through mitochondrial reactive oxygen species (mtROS). mtROS regulate kinases and transcription factors in mitohormetic responses that favour adaptation to toxic insults. IF1 is tissue-specifically expressed and in human and mouse brain is in molar excess over the ATP synthase. Herein, we have used genetic approaches to ablate or overexpress IF1 in neurons to investigate its role in brain functions. IF1 inhibits a fraction of the ATP synthase under physiological conditions and regulates respiration, mtROS production and mitochondrial structure. Transcriptomic, proteomic and metabolomic analyses indicate that IF1 regulates synaptic transmission and cognition. Ablation of IF1 impairs short-term memory whereas IF1 overexpression increases basal synaptic transmission and learning by mtROS-dependent activation of the extracellular signal-regulated kinases 1/2 (ERK 1/2). Overall, we show that IF1 dose plays a fundamental role in the regulation of neuronal function by controlling the fraction of inhibited ATP synthase that acts as source of mitohormetic mtROS, further emphasizing the ATP synthase/IF1 as promising targets to treat cognitive disorders.
Project description:Defects of mitochondrial functions lead in humans to vast array of usually multisystemic pathologies and several hundreds of diseases resulting from various defects of mitochondria biogenesis and maintenance, defects of respiratory chain complexes (OXPHOS) or defects of individual mitochondrial proteins are known. We used Agilent Whole Human Genome Microarray for gene expression profiling of genetically heterogeneous group of 13 patients with biochemically proven ATP synthase deficiency. Gene expression data analysis allowed classification of patients into several distinct groups, provided information on subgroup and patient specific gene expression profiles, defined candidate disease causing genes and gave basic information on pathogenic mechanisms associated with ATP synthase deficiency. Keywords: ATP synthase, mitochondrial biogenesis, ROS, gene expression, microarray, human
Project description:Ectopic ATP synthase is a functional onco-protein increases cell proliferation when transported to plasma membrane of cancer cells. Our previous study performed large scale gene silencing screening indicated ER and mitochondrial transport pathways may lead to ectopic ATP synthase expression. Silencing dynamin-related protein 1 (Drp1), mitofusin-1 (Mfn1) and Parkin affected ectopic ATP synthases expression. However, the underlying trafficking mechanism is poorly understood. Here, we analyzed our membrane and mitochondrial proteome of lung cancer A549 cells and found that both nuclear-encoded ATP synthase subunits and mitochondrial-encoded components-ATP6 translocated to cell surface, indicating that ATP synthase subunits assembled in mitochondria. Furthermore, serum starvation enhanced ATP synthase translocation to plasma membrane, Mdivi-1, a chemical inhibitor of the mitochondrial fission protein Drp1, rescued the phenomena. Additionally, image quantification of mitochondria, showing that mitochondrial fission preference cells expressed more eATP synthase. Therefore, we proposed that eATP synthase trafficking may be related to mitochondrial dynamics. Additionally, ICC and flow cytometry revealed the expression of a critical transcription factor associated with high-risk neuroblastoma, MYCN, correlated with eATP synthase expression. To better understand whether MYCN mediated mitochondrial fission and affected ATP synthase trafficking, we first analyzed MYCN ChIP-sequencing data and found Drp1, Mfns and Parkin possessed the consensus DNA-binding motif of MYCN. Further high-resolution image analysis showed higher mitochondrial fission and eATP synthase expression in MYCN-amplified neuroblastoma. Last, silencing MYCN reduced the fission level by detecting DRP1. In summary, we suggest that trafficking of ectopic ATP synthase may via mitochondrial dynamics.
Project description:ngs2019_18_eplus-eplus-search for mitochondrial editing defect in an arabidopsis PPR mutant Annotation, RNA/Small-RNA quantification: editing quantification. The Mito samples were first enriched with mitochondria by a series of multi-speed centrifugations after grinding with mortar at 4°C.