The Experts below are selected from a list of 297 Experts worldwide ranked by ideXlab platform
Ralph Bock - One of the best experts on this subject based on the ideXlab platform.
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gun control in retrograde signaling how genomes uncoupled proteins adjust Nuclear Gene expression to plastid bioGenesis
The Plant Cell, 2021Co-Authors: Ralph BockAbstract:Communication between cellular compartments is vital for development and environmental adaptation. Signals emanating from organelles, so-called retrograde signals, coordinate Nuclear Gene expression with the developmental stage and/or the functional status of the organelle. Plastids (best known in their green photosynthesizing differentiated form, the chloroplasts) are the primary energy-producing compartment of plant cells, and the site for the biosynthesis of many metabolites, including fatty acids, amino acids, nucleotides, isoprenoids, tetrapyrroles, vitamins, and phytohormone precursors. Signals derived from plastids regulate the accumulation of a large set of nucleus-encoded proteins, many of which localize to plastids. A set of mutants defective in retrograde signaling (genomes uncoupled, or gun) was isolated over 25 years ago. While most GUN Genes act in tetrapyrrole biosynthesis, resolving the molecular function of GUN1, the proposed integrator of multiple retrograde signals, has turned out to be particularly challenging. Based on its amino acid sequence, GUN1 was initially predicted to be a plastid-localized nucleic acid-binding protein. Only recently, mechanistic information on the function of GUN1 has been obtained, pointing to a role in plastid protein homeostasis. This review article summarizes our current understanding of GUN-related retrograde signaling and provides a critical appraisal of the various proposed roles for GUNs and their respective pathways.
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Extensive Posttranscriptional Regulation of Nuclear Gene Expression by Plastid Retrograde Signals.
Plant physiology, 2019Co-Authors: Etienne H. Meyer, Ralph BockAbstract:Retrograde signals emanate from the DNA-containing cell organelles (plastids and mitochondria) and control the expression of a large number of Nuclear Genes in response to environmental and developmental cues. Previous studies on retrograde signaling have mainly analyzed the regulation of Nuclear Gene expression at the transcript level. To determine the contribution of translational and posttranslational regulation to plastid retrograde signaling, we combined label-free proteomics with transcriptomic analysis of Arabidopsis (Arabidopsis thaliana) seedlings and studied their response to interference with the plastid Gene expression pathway of retrograde signaling. By comparing the proteomes of the genomes uncoupled1 (gun1) and gun5 mutants with the wild type, we show that GUN1 is critical in the maintenance of plastid protein homeostasis (proteostasis) when plastid translation is blocked. Combining transcriptomic and proteomic analyses of the wild type and gun1, we identified 181 highly translationally or posttranslationally regulated (HiToP) Genes. We demonstrate that HiToP photosynthesis-associated Nuclear Genes (PhANGs) are largely regulated by translational repression, while HiToP ribosomal protein Genes are regulated posttranslationally, likely at the level of protein stability without the involvement of GUN1. Our findings suggest distinct posttranscriptional control mechanisms of Nuclear Gene expression in response to plastid-derived retrograde signals. They also reveal a role for GUN1 in the translational regulation of several PhANGs and highlight extensive posttranslational regulation that does not necessitate GUN1. This study advances our understanding of the molecular mechanisms underlying intracellular communication and provides new insight into cellular responses to impaired plastid protein biosynthesis.
Joanne Chory - One of the best experts on this subject based on the ideXlab platform.
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Sigma factor-mediated plastid retrograde signals control Nuclear Gene expression
The Plant journal : for cell and molecular biology, 2012Co-Authors: Jesse D. Woodson, Juan Manuel Pérez-ruiz, Robert J. Schmitz, Joseph R. Ecker, Joanne ChoryAbstract:Summary Retrograde signalling from plastids to the nucleus is necessary to regulate the organelle's proteome during the establishment of photoautotrophy and fluctuating environmental conditions. Studies that used inhibitors of chloroplast bioGenesis have revealed that hundreds of Nuclear Genes are regulated by retrograde signals emitted from plastids. Plastid Gene expression is the source of at least one of these signals, but the number of signals and their mechanisms used to regulate Nuclear Gene expression are unknown. To further examine the effects of plastid Gene expression on Nuclear Gene expression, we analyzed Arabidopsis mutants that were defective in each of the six sigma factor (SIG) Genes that encode proteins utilized by plastid-encoded RNA polymerase to transcribe specific sets of plastid Genes. We showed that SIG2 and SIG6 have partially redundant roles in plastid transcription and retrograde signalling to control Nuclear Gene expression. The loss of GUN1 (a plastid-localized pentatricopeptide repeat protein) is able to restore Nuclear (but not plastid) Gene expression in both sig2 and sig6, whereas an increase in heme synthesis is able to restore Nuclear Gene expression in sig2 mutants only. These results demonstrate that sigma factor function is the source of at least two retrograde signals to the nucleus; one likely to involve the transcription of tRNAGlu. A microarray analysis showed that these two signals accounted for at least one subset of the Nuclear Genes that are regulated by the plastid bioGenesis inhibitors norflurazon and lincomycin. Together these data suggest that such inhibitors can induce retrograde signalling by affecting transcription in the plastid.
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Signals from chloroplasts converge to regulate Nuclear Gene expression
Science, 2007Co-Authors: Shai Koussevitzky, Jason Lim, Ajit Nott, Gilberto Sachetto-martins, Marci Surpin, Fangxin Hong, Ron Mittler, Todd C. Mockler, Joanne ChoryAbstract:Plastid-to-nucleus retrograde signaling coordinates Nuclear Gene expression with chloroplast function and is essential for the photoautotrophic life-style of plants. Three retrograde signals have been described, but little is known of their signaling pathways. We show here that GUN1, a chloroplast-localized pentatricopeptide-repeat protein, and ABI4, an Apetala 2 (AP2)–type transcription factor, are common to all three pathways. ABI4 binds the promoter of a retrograde-regulated Gene through a conserved motif found in close proximity to a light-regulatory element. We propose a model in which multiple indicators of aberrant plastid function in Arabidopsis are integrated upstream of GUN1 within plastids, which leads to ABI4- mediated repression of Nuclear-encoded Gene
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the phosphoenolpyruvate phosphate translocator is required for phenolic metabolism palisade cell development and plastid dependent Nuclear Gene expression
The Plant Cell, 1999Co-Authors: Stephen J Streatfield, Andreas P M Weber, Elizabeth A Kinsman, Rainer E Hausler, Jianming Li, Dusty Postbeittenmiller, Werner M Kaiser, Kevin A Pyke, Ulfingo Flugge, Joanne ChoryAbstract:The Arabidopsis chlorophyll a / b binding protein ( CAB ) Gene underexpressed 1 ( cue1 ) mutant underexpresses light-regulated Nuclear Genes encoding chloroplast-localized proteins. cue1 also exhibits mesophyll-specific chloroplast and cellular defects, resulting in reticulate leaves. Both the Gene underexpression and the leaf cell morphology phenotypes are dependent on light intensity. In this study, we determine that CUE1 encodes the plastid inner envelope phosphoenolpyruvate/phosphate translocator (PPT) and define amino acid residues that are critical for translocator function. The biosynthesis of aromatics is compromised in cue1 , and the reticulate phenotype can be rescued by feeding aromatic amino acids. Determining that CUE1 encodes PPT indicates the in vivo role of the translocator in metabolic partitioning and reveals a mesophyll cell‐specific requirement for the translocator in Arabidopsis leaves. The Nuclear Gene expression defects in cue1 suggest that a light intensity‐dependent interorganellar signal is modulated through metabolites dependent on a plastid supply of phosphoenolpyruvate.
Changhan Lee - One of the best experts on this subject based on the ideXlab platform.
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the mitochondrial encoded peptide mots c translocates to the nucleus to regulate Nuclear Gene expression in response to metabolic stress
Cell Metabolism, 2018Co-Authors: Kyung Hwa Kim, Jyung Mean Son, Berenice A Benayoun, Changhan LeeAbstract:Cellular homeostasis is coordinated through communication between mitochondria and the nucleus, organelles that each possess their own genomes. Whereas the mitochondrial genome is regulated by factors encoded in the nucleus, the Nuclear genome is currently not known to be actively controlled by factors encoded in the mitochondrial DNA. Here, we show that MOTS-c, a peptide encoded in the mitochondrial genome, translocates to the nucleus and regulates Nuclear Gene expression following metabolic stress in a 5'-adenosine monophosphate-activated protein kinase (AMPK)-dependent manner. In the nucleus, MOTS-c regulated a broad range of Genes in response to glucose restriction, including those with antioxidant response elements (ARE), and interacted with ARE-regulating stress-responsive transcription factors, such as Nuclear factor erythroid 2-related factor 2 (NFE2L2/NRF2). Our findings indicate that the mitochondrial and Nuclear genomes co-evolved to independently encode for factors to cross-regulate each other, suggesting that mitoNuclear communication is Genetically integrated.
Thomas Pfannschmidt - One of the best experts on this subject based on the ideXlab platform.
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environmental control of plant Nuclear Gene expression by chloroplast redox signals
Frontiers in Plant Science, 2012Co-Authors: Jeannette Pfalz, Monique Liebers, Matthias Hirth, Bjorn Grubler, Ute Holtzegel, Yvonne Schroter, Lars Dietzel, Thomas PfannschmidtAbstract:Plant photosynthesis takes place in specialised cell organelles, the chloroplasts, which perform all essential steps of this process. The proteins involved in photosynthesis are encoded by Genes located on the plastid and Nuclear genomes. Proper function and regulation of light harvesting and energy fixation thus requires a tight coordination of the Gene expression machineries in the two Genetic compartments. This is achieved by a bi-directional exchange of information between nucleus and plastids. Signals emerging from plastids report the functional and developmental state of the organelle to the nucleus and initiate distinct Nuclear Gene expression profiles, which trigger responses that support or improve plastid functions. Recent research indicated that this signalling is absolutely essential for plant growth and development. Reduction/oxidation (redox) signals from photosynthesis are key players in this information network since they do report functional disturbances in photosynthesis, the primary energy source of plants. Such disturbances are caused by environmental fluctuations for instance in illumination, temperature or water availability. These environmental changes affect the linear electron flow of photosynthesis and result in changes of the redox state of the components involved (e.g. the plastoquinone pool) or coupled to it (e.g. the thioredoxin pool). Thus, the changes in redox state directly reflect the environmental impact and serve as immediate plastidial signals to the nucleus. The triggered responses range from counterbalancing reactions within the physiological range up to severe stress responses including cell death. This review focuses on physiological redox signals from photosynthetic electron transport, their relation to the environment, potential transduction pathways to the nucleus and their impact on Nuclear Gene expression.
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Photosynthetic redox control of Nuclear Gene expression
Journal of experimental botany, 2005Co-Authors: Vidal Fey, Raik Wagner, Katharina Bräutigam, Thomas PfannschmidtAbstract:Chloroplasts contain 3000-4000 different proteins but only a small subset of them is encoded in the plastid genome while the majority is encoded in the nucleus. Expression of these Genes therefore requires a high degree of co-ordination between nucleus and chloroplast. This is achieved by a bilateral information exchange between both compartments including nucleus-to-plastid (anterograde) and plastid-to-nucleus (retrograde) signals. The latter represent a functional feedback control which couples the expression of Nuclear encoded plastid proteins to the actual functional state of the organelle. The efficiency of photosynthesis is a very important parameter in this context since it is influenced by many environmental conditions and therefore represents a sensor for the residing environment. Components of the photosynthetic electron transport chain exhibit significant changes in their reduction/oxidation (redox) state depending on the photosynthetic electron flow and therefore serve as signalling parameters which report environmental influences on photosynthesis. Such redox signals control chloroplast and Nuclear Gene expression events and play an important role in the co-ordination of both Genetic compartments. It is discussed here which photosynthetic parameters are known to control Nuclear Gene expression, how these signals are transduced toward the nucleus, and how they interact with other plastid retrograde signals and cytosolic light perception systems.
Janet K. Rosenthal - One of the best experts on this subject based on the ideXlab platform.
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PET112, a Saccharomyces cerevisiae Nuclear Gene required to maintain rho ^+ mitochondrial DNA
Current Genetics, 1994Co-Authors: Julio J. Mulero, Janet K. RosenthalAbstract:The Nuclear Gene PET112 was originally identified by a mutation ( pet112-1 ) that specifically blocked accumulation of cytochrome c oxidase subunit II. The mutation causes a post-transcriptional defect since the level of COX2 mRNA in the mutant is the same as in the wildtype. However, PET112 does not have a function similar to that of PET111 , a COX2 mRNA-specific translational activator: while pet111 mutations are suppressed by chimeric COX2 mRNAs bearing 5′ leaders of other mitochondrial mRNAs, pet112-1 is not. The PET112 Gene was isolated and shown to code a protein of 541 residues (62 kDa) with no significant homology to known amino-acid sequences. By hybridization to defined genomic clones the Gene was mapped to chromosome II between cdc25 and ilsl . Disruption of the PET112 open reading frame destabilized the mitochondrial genome, causing cells to become rho^-. This finding suggests that PET112 has an important General function in mitochondrial Gene expression, probably in translation.
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PET112, a Saccharomyces cerevisiae Nuclear Gene required to maintain rho ^+ mitochondrial DNA
Current Genetics, 1994Co-Authors: Julio J. Mulero, Janet K. Rosenthal, Thomas D. FoxAbstract:The Nuclear Gene PET112 was originally identified by a mutation ( pet112-1 ) that specifically blocked accumulation of cytochrome c oxidase subunit II. The mutation causes a post-transcriptional defect since the level of COX2 mRNA in the mutant is the same as in the wildtype. However, PET112 does not have a function similar to that of PET111 , a COX2 mRNA-specific translational activator: while pet111 mutations are suppressed by chimeric COX2 mRNAs bearing 5′ leaders of other mitochondrial mRNAs, pet112-1 is not. The PET112 Gene was isolated and shown to code a protein of 541 residues (62 kDa) with no significant homology to known amino-acid sequences. By hybridization to defined genomic clones the Gene was mapped to chromosome II between cdc25 and ilsl . Disruption of the PET112 open reading frame destabilized the mitochondrial genome, causing cells to become rho^-. This finding suggests that PET112 has an important General function in mitochondrial Gene expression, probably in translation.
