Multilevel Regulation of Peroxisomal Proteome by Post-Translational Modifications

Peroxisomes, which are ubiquitous organelles in all eukaryotes, are highly dynamic organelles that are essential for development and stress responses. Plant peroxisomes are involved in major metabolic pathways, such as fatty acid β-oxidation, photorespiration, ureide and polyamine metabolism, in the biosynthesis of jasmonic, indolacetic, and salicylic acid hormones, as well as in signaling molecules such as reactive oxygen and nitrogen species (ROS/RNS). Peroxisomes are involved in the perception of environmental changes, which is a complex process involving the regulation of gene expression and protein functionality by protein post-translational modifications (PTMs). Although there has been a growing interest in individual PTMs in peroxisomes over the last ten years, their role and cross-talk in the whole peroxisomal proteome remain unclear. This review provides up-to-date information on the function and crosstalk of the main peroxisomal PTMs. Analysis of whole peroxisomal proteomes shows that a very large number of peroxisomal proteins are targeted by multiple PTMs, which affect redox balance, photorespiration, the glyoxylate cycle, and lipid metabolism. This multilevel PTM regulation could boost the plasticity of peroxisomes and their capacity to regulate metabolism in response to environmental changes.

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Co-ordinate regulation of genes involved in storage lipid mobilization in Arabidopsis thaliana

Biochemical Society Transactions ◽

10.1042/bst0290283 ◽

2001 ◽

Vol 29 (2) ◽

pp. 283-286 ◽

Cited By ~ 54

Author(s):

E. L. Rylott ◽

M. A. Hooks ◽

I. A. Graham

Keyword(s):

Arabidopsis Thaliana ◽

Enzyme Activities ◽

Phosphoenolpyruvate Carboxykinase ◽

Isocitrate Lyase ◽

Glyoxylate Cycle ◽

Molecular Genetic ◽

Regulation Of Gene Expression ◽

Growth Period ◽

Malate Synthase ◽

The Glyoxylate Cycle

Molecular genetic approaches in the model plant Arabidopsis thaliana (ColO) are shedding new light on the role and control of the pathways associated with the mobilization of lipid reserves during oilseed germination and post-germinative growth. Numerous independent studies have reported on the expression of individual genes encoding enzymes from the three major pathways: β-oxidation, the glyoxylate cycle and gluconeogenesis. However, a single comprehensive study of representative genes and enzymes from the different pathways in a single plant species has not been done. Here we present results from Arabidopsis that demonstrate the co-ordinate regulation of gene expression and enzyme activities for the acyl-CoA oxidase- and 3-ketoacyl-CoA thiolasemediated steps of β-oxidation, the isocitrate lyase and malate synthase steps of the glyoxylate cycle and the phosphoenolpyruvate carboxykinase step of gluconeogenesis. The mRNA abundance and enzyme activities increase to a peak at stage 2, 48 h after the onset of seed germination, and decline thereafter either to undetectable levels (for malate synthase and isocitrate lyase) or low basal levels (for the genes of β-oxidation and gluconeogenesis). The co-ordinate induction of all these genes at the onset of germination raises the possibility that a global regulatory mechanism operates to induce the expression of genes associated with the mobilization of storage reserves during the heterotrophic growth period.

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Universal Molecular Triggers of Stress Responses in Cyanobacterium Synechocystis

Life ◽

10.3390/life9030067 ◽

2019 ◽

Vol 9 (3) ◽

pp. 67 ◽

Cited By ~ 3

Author(s):

Kirill S. Mironov ◽

Maria A. Sinetova ◽

Maria Shumskaya ◽

Dmitry A. Los

Keyword(s):

Cold Stress ◽

Stress Responses ◽

Environmental Changes ◽

Regulation Of Gene Expression ◽

Photosynthetic Electron Transport ◽

Membrane Turnover ◽

Destructive Effect ◽

Strong Light ◽

Synechocystis Sp ◽

Pcc 6803

Systemic analysis of stress-induced transcription in the cyanobacterium Synechocystis sp. strain PCC 6803 identifies a number of genes as being induced in response to most abiotic stressors (heat, osmotic, saline, acid stress, strong light, and ultraviolet radiation). Genes for heat-shock proteins (HSPs) are activated by all these stresses and form a group that universally responds to all environmental changes. The functions of universal triggers of stress responses in cyanobacteria can be performed by reactive oxygen species (ROS), in particular H2O2, as well as changes in the redox potential of the components of the photosynthetic electron transport chain. The double mutant of Synechocystis sp. PCC 6803 (katG/tpx, or sll1987/sll0755), which is defective in antioxidant enzymes catalase (KatG) and thioredoxin peroxidase (Tpx), cannot grow in the presence of exogenous hydrogen peroxide (H2O2); and it is extremely sensitive to low concentrations of H2O2, especially under conditions of cold stress. Experiments on this mutant demonstrate that H2O2 is involved in regulation of gene expression that responds to a decrease in ambient temperature, and affects both the perception and the signal transduction of cold stress. In addition, they suggest that formation of ROS largely depends on the physical state of the membranes such as fluidity or viscosity. In cyanobacteria, an increase in membrane turnover leads to a decrease in the formation of ROS and an increase in resistance to cold stress. Therefore: (1) H2O2 is the universal trigger of stress responses in cyanobacterial cells; (2) ROS formation (in particular, H2O2) depends on the physical properties of both cytoplasmic and thylakoid membranes; (3) The destructive effect of H2O2 is reduced by increasing of fluidity of biological membranes.

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Nutrient Sensing and Redox Balance: GCN2 as a New Integrator in Aging

Oxidative Medicine and Cellular Longevity ◽

10.1155/2019/5730532 ◽

2019 ◽

Vol 2019 ◽

pp. 1-9 ◽

Cited By ~ 4

Author(s):

Paulina Falcón ◽

Marcela Escandón ◽

Álvaro Brito ◽

Soledad Matus

Keyword(s):

Stress Responses ◽

Redox Balance ◽

Nutritional Stress ◽

Nutrient Sensing ◽

Cellular Processes ◽

Complex Process ◽

Probability Of Death ◽

Stress Sensing ◽

Amino Acid Sensing

Aging is a complex process in which the accumulation of molecular, cellular, and organism dysfunction increases the probability of death. Several pieces of evidence have revealed a contribution of stress responses in aging and in aging-related diseases, in particular, the key role of signaling pathways associated to nutritional stress. Here, we review the possible interplay between amino acid sensing and redox balance maintenance mediated by the nutritional sensor general control nonderepressive 2 (GCN2). We discuss this new dimension of nutritional stress sensing consequences, standing out GCN2 as a central coordinator of key cellular processes that assure healthy homeostasis in the cell, raising GCN2 as a novel interesting target, that when activated, could imply pleiotropic benefits, particularly GCN2 intervention and its new unexplored therapeutic role as a player in the aging process.

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Mutants of Saccharomyces cerevisiae with Defects in Acetate Metabolism: Isolation and Characterization of Acn− Mutants

Genetics ◽

10.1093/genetics/144.1.57 ◽

1996 ◽

Vol 144 (1) ◽

pp. 57-69 ◽

Cited By ~ 7

Author(s):

Mark T McCammon

Keyword(s):

Saccharomyces Cerevisiae ◽

Glyoxylate Cycle ◽

Tca Cycle ◽

Acetate Metabolism ◽

Yeast Saccharomyces Cerevisiae ◽

Isolation And Characterization ◽

Complex Process ◽

Metabolic Interactions ◽

Cellular Compartments ◽

The Glyoxylate Cycle

Abstract The two carbon compounds, ethanol and acetate, can be oxidatively metabolized as well as assimilated into carbohydrate in the yeast Saccharomyces cerevisiae. The distribution of acetate metabolic enzymes among several cellular compartments, mitochondria, peroxisomes, and cytoplasm makes it an intriguing system to study complex metabolic interactions. To investigate the complex process of carbon catabolism and assimilation, mutants unable to grow on acetate were isolated. One hundred five Acn− (“Acetate Nonutilizing”) mutants were sorted into 21 complementation groups with an additional 20 single mutants. Five of the groups have defects in TCA cycle enzymes: MDH1, CIT1, ACO1, IDH1, and IDH2. A defect in RTG2, involved in the retrograde communication between the mitochondrion and the nucleus, was also identified. Four genes encode enzymes of the glyoxylate cycle and gluconeogenesis: ICL1, MLS1, MBH2, and PCK1. Five other genes appear to be defective in regulating metabolic activity since elevated levels of enzymes in several metabolic pathways, including the glyoxylate cycle, gluconeogenesis, and acetyl-coA metabolism, were detected in these mutants: ACN8, ACN9, ACNl7, ACN18, and ACN42. In summary, this analysis has identified at least 22 and as many as 41 different genes involved in acetate metabolism.

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Linking transcription, RNA polymerase II elongation and alternative splicing

Biochemical Journal ◽

10.1042/bcj20200475 ◽

2020 ◽

Vol 477 (16) ◽

pp. 3091-3104 ◽

Cited By ~ 1

Author(s):

Luciana E. Giono ◽

Alberto R. Kornblihtt

Keyword(s):

Gene Expression ◽

Alternative Splicing ◽

Rna Polymerase Ii ◽

Environmental Changes ◽

Transcription Elongation ◽

Single Gene ◽

Regulation Of Gene Expression ◽

Regulation Of Transcription ◽

Stepping Stones ◽

Eukaryotic Transcription

Gene expression is an intricately regulated process that is at the basis of cell differentiation, the maintenance of cell identity and the cellular responses to environmental changes. Alternative splicing, the process by which multiple functionally distinct transcripts are generated from a single gene, is one of the main mechanisms that contribute to expand the coding capacity of genomes and help explain the level of complexity achieved by higher organisms. Eukaryotic transcription is subject to multiple layers of regulation both intrinsic — such as promoter structure — and dynamic, allowing the cell to respond to internal and external signals. Similarly, alternative splicing choices are affected by all of these aspects, mainly through the regulation of transcription elongation, making it a regulatory knob on a par with the regulation of gene expression levels. This review aims to recapitulate some of the history and stepping-stones that led to the paradigms held today about transcription and splicing regulation, with major focus on transcription elongation and its effect on alternative splicing.

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Mitochondrial Sirtuins in Reproduction

Antioxidants ◽

10.3390/antiox10071047 ◽

2021 ◽

Vol 10 (7) ◽

pp. 1047

Author(s):

Giovanna Di Emidio ◽

Stefano Falone ◽

Paolo Giovanni Artini ◽

Fernanda Amicarelli ◽

Anna Maria D’Alessandro ◽

...

Keyword(s):

Stress Responses ◽

Metabolic Pathways ◽

Redox Balance ◽

Antioxidant Defenses ◽

Metabolic Abnormalities ◽

Female Reproduction ◽

Mitochondrial Dysfunctions ◽

Early Embryos ◽

The Relationship

Mitochondria act as hubs of numerous metabolic pathways. Mitochondrial dysfunctions contribute to altering the redox balance and predispose to aging and metabolic alterations. The sirtuin family is composed of seven members and three of them, SIRT3-5, are housed in mitochondria. They catalyze NAD+-dependent deacylation and the ADP-ribosylation of mitochondrial proteins, thereby modulating gene expression and activities of enzymes involved in oxidative metabolism and stress responses. In this context, mitochondrial sirtuins (mtSIRTs) act in synergistic or antagonistic manners to protect from aging and aging-related metabolic abnormalities. In this review, we focus on the role of mtSIRTs in the biological competence of reproductive cells, organs, and embryos. Most studies are focused on SIRT3 in female reproduction, providing evidence that SIRT3 improves the competence of oocytes in humans and animal models. Moreover, SIRT3 protects oocytes, early embryos, and ovaries against stress conditions. The relationship between derangement of SIRT3 signaling and the imbalance of ROS and antioxidant defenses in testes has also been demonstrated. Very little is known about SIRT4 and SIRT5 functions in the reproductive system. The final goal of this work is to understand whether sirtuin-based signaling may be taken into account as potential targets for therapeutic applications in female and male infertility.

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Heatwave frequency and seedling death alter stress-specific emissions of volatile organic compounds in Aleppo pine

Oecologia ◽

10.1007/s00442-021-04905-y ◽

2021 ◽

Author(s):

Benjamin Birami ◽

Ines Bamberger ◽

Andrea Ghirardo ◽

Rüdiger Grote ◽

Almut Arneth ◽

...

Keyword(s):

Volatile Organic Compounds ◽

Gas Exchange ◽

Organic Compounds ◽

Stress Responses ◽

Methyl Salicylate ◽

Environmental Changes ◽

Pinus Halepensis ◽

Dark Respiration ◽

Seedling Mortality ◽

Volatile Organic

AbstractBiogenic volatile organic compounds (BVOC) play important roles in plant stress responses and can serve as stress indicators. While the impacts of gradual environmental changes on BVOCs have been studied extensively, insights in emission responses to repeated stress and recovery are widely absent. Therefore, we studied the dynamics of shoot gas exchange and BVOC emissions in Pinus halepensis seedlings during an induced moderate drought, two four-day-long heatwaves, and the combination of drought and heatwaves. We found clear stress-specific responses of BVOC emissions. Reductions in acetone emissions with declining soil water content and transpiration stood out as a clear drought indicator. All other measured BVOC emissions responded exponentially to rising temperatures during heat stress (maximum of 43 °C), but monoterpenes and methyl salicylate showed a reduced temperature sensitivity during the second heatwave. We found that these decreases in monoterpene emissions between heatwaves were not reflected by similar declines in their internal storage pools. Because stress intensity was extremely severe, most of the seedlings in the heat-drought treatment died at the end of the second heatwave (dark respiration ceased). Interestingly, BVOC emissions (methanol, monoterpenes, methyl salicylate, and acetaldehyde) differed between dying and surviving seedlings, already well before indications of a reduced vitality became visible in gas exchange dynamics. In summary, we could clearly show that the dynamics of BVOC emissions are sensitive to stress type, stress frequency, and stress severity. Moreover, we found indications that stress-induced seedling mortality was preceded by altered methanol, monoterpene, and acetaldehyde emission dynamics.

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Stress Responses in Down Syndrome Neurodegeneration: State of the Art and Therapeutic Molecules

Biomolecules ◽

10.3390/biom11020266 ◽

2021 ◽

Vol 11 (2) ◽

pp. 266

Author(s):

Chiara Lanzillotta ◽

Fabio Di Domenico

Keyword(s):

Down Syndrome ◽

Stress Response ◽

Stress Responses ◽

Redox Balance ◽

Antioxidant Response ◽

Chromosome 21 ◽

Therapeutic Approaches ◽

Genomic Disorder ◽

Therapeutic Molecules ◽

Early Alzheimer’S Disease

Down syndrome (DS) is the most common genomic disorder characterized by the increased incidence of developing early Alzheimer’s disease (AD). In DS, the triplication of genes on chromosome 21 is intimately associated with the increase of AD pathological hallmarks and with the development of brain redox imbalance and aberrant proteostasis. Increasing evidence has recently shown that oxidative stress (OS), associated with mitochondrial dysfunction and with the failure of antioxidant responses (e.g., SOD1 and Nrf2), is an early signature of DS, promoting protein oxidation and the formation of toxic protein aggregates. In turn, systems involved in the surveillance of protein synthesis/folding/degradation mechanisms, such as the integrated stress response (ISR), the unfolded stress response (UPR), and autophagy, are impaired in DS, thus exacerbating brain damage. A number of pre-clinical and clinical studies have been applied to the context of DS with the aim of rescuing redox balance and proteostasis by boosting the antioxidant response and/or inducing the mechanisms of protein re-folding and clearance, and at final of reducing cognitive decline. So far, such therapeutic approaches demonstrated their efficacy in reverting several aspects of DS phenotype in murine models, however, additional studies aimed to translate these approaches in clinical practice are still needed.

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