A Tale of Two Genomes: Role of a Chloroplast Signal in Coordinating Nuclear and Plastid Genome Expression

1992 ◽  
Vol 19 (4) ◽  
pp. 387 ◽  
Author(s):  
RE Susek ◽  
J Chory
Keyword(s):  
Chloroplast Development ◽  
Photosynthetic Apparatus ◽  
Signal Transduction Pathway ◽  
Nuclear Genes ◽  
Signal Molecules ◽  
Chloroplast Gene Expression ◽  
Genome Expression ◽  
Coordinate Control ◽  
Genes Encoding

Plant cells coordinately regulate the expression of nuclear and plastid genes that encode components of the photosynthetic apparatus. Nuclear genes that regulate chloroplast development and chloroplast gene expression provide part of this coordinate control. However, there is compelling evidence that information also flows in the opposite direction, from chloroplasts to the nucleus. This hypothesised, second pathway functions to coordinate the expression of nuclear genes encoding components of the photosynthetic apparatus with the functional state of the chloroplast. Here we review the evidence for the signal transduction pathway from the chloroplasts to the nucleus and suggest possible signal molecules.

Chlamydomonas nuclear mutants that fail to assemble respiratory or photosynthetic electron transfer complexes

2001 ◽  
Vol 29 (4) ◽  
pp. 452-455 ◽  
Author(s):  
F. J. Lown ◽  
A. T. Watson ◽  
S. Purton
Keyword(s):  
Electron Transfer ◽  
Green Alga ◽  
Molecular Genetic ◽  
Nuclear Genes ◽  
Genetic Approach ◽  
Structural Components ◽  
Genes Encoding ◽  
Photosynthetic Electron Transfer

We are using a molecular-genetic approach to investigate the role of nuclear genes in the biogenesis of the electron transfer complexes of mitochondria and chloroplasts. Our analysis of nuclear mutants of the green alga Chlamydomonas that are defective in respiration or photosynthesis has led to the identification of genes encoding factors required for the expression of specific organellar genes, and genes encoding structural components of the complexes.

OsSIG2A is required for chloroplast development in rice (Oryza sativa L.) at low temperature by regulating plastid genes expression

2019 ◽  
Vol 46 (8) ◽  
pp. 766 ◽  
Author(s):  
Yang Yu ◽  
Zhenling Zhou ◽  
Hanchun Pu ◽  
Baoxiang Wang ◽  
Yunhui Zhang ◽  
...  
Keyword(s):  
Low Temperature ◽  
Low Temperatures ◽  
Chloroplast Development ◽  
Oryza Sativa L ◽  
Photosynthetic Apparatus ◽  
Development Stage ◽  
Specific Gene ◽  
Genes Expression ◽  
Young Leaves

The chloroplast is an essential photosynthetic apparatus that is more sensitive to low temperatures than other organelles. Sigma factors were revealed regulating specific gene expression for maintaining photosynthetic efficiency and adapting to physiological and environmental conditions. However, the regulatory mechanisms of SIG genes supporting chloroplast development under low temperature in rice have not yet been reported. Here, we uncovered the essential role of OsSIG2A in rice chloroplast development at low temperatures by a newly reported thermo-sensitive chlorophyll deficient 12 (tcd12) mutant, which exhibited albino leaves with decreased chlorophyll content and malformed chloroplasts at seedling stage under low temperature. OsSIG2A is a typical chloroplast-localised RNA polymerase sigma factor, and constitutively expresses in different rice tissues, especially for young leaves and stems. Moreover, the transcription level of both PEP- and NEP- dependent genes, which are necessary for chloroplast development at early leaf development stage, was greatly affected in the tcd12 mutant under low temperature. Taken together, our findings indicate that OsSIG2A is required for early chloroplast differentiation under low temperatures by regulating plastid genes expression.

scholarly journals GUN1 regulates tetrapyrrole biosynthesis

2019 ◽  
Author(s):  
Takayuki Shimizu ◽  
Nobuyoshi Mochizuki ◽  
Akira Nagatani ◽  
Satoru Watanabe ◽  
Tomohiro Shimada ◽  
...  
Keyword(s):  
Chloroplast Development ◽  
Photosynthetic Apparatus ◽  
Nuclear Gene ◽  
Retrograde Signaling ◽  
Tetrapyrrole Biosynthesis ◽  
Metal Porphyrins ◽  
Nuclear Gene Expression ◽  
Chloroplast Genomes ◽  
Tetrapyrrole Metabolism

The biogenesis of the photosynthetic apparatus in developing chloroplasts requires the assembly of proteins encoded on both nuclear and chloroplast genomes1. To co-ordinate this process there needs to be communication between these organelles, and while we have a good understanding of how the nucleus controls chloroplast development, how the chloroplast communicates with the nucleus at this time is still essentially unknown2. What we do know comes from pioneering work in which a series of genomes uncoupled (gun) mutants were identified that show elevated nuclear gene expression after chloroplast damage3. Of the six reported gun mutations, five are in tetrapyrrole biosynthesis proteins4-6 and this has led to the development of a model for chloroplast-to-nucleus retrograde signaling in which ferrochelatase 1 (FC1)-dependent heme synthesis generates a positive signal promoting expression of photosynthesis-related genes6. However, the molecular consequences of the strongest of the gun mutants, gun17, is unknown, preventing the development of a unifying hypothesis for chloroplast-to-nucleus signaling. Here, we show that GUN1 directly binds to heme and other metal-porphyrins, affects flux through the tetrapyrrole biosynthesis pathway and can increase the chelatase activity of FC1. These results raise the possibility that the signaling role of GUN1 may be manifested through changes in tetrapyrrole metabolism and supports a role for tetrapyrroles as mediators of a single biogenic chloroplast-to-nucleus retrograde signaling pathway.

DNA methylation in satellite repeats disorders

2019 ◽  
Vol 63 (6) ◽  
pp. 757-771 ◽  
Author(s):  
Claire Francastel ◽  
Frédérique Magdinier
Keyword(s):  
Dna Methylation ◽  
Human Genome ◽  
Repetitive Dna ◽  
Dna Sequences ◽  
Satellite Repeats ◽  
Tremendous Progress ◽  
Genes Encoding ◽  
Dna Elements ◽  
Near Future

Abstract Despite the tremendous progress made in recent years in assembling the human genome, tandemly repeated DNA elements remain poorly characterized. These sequences account for the vast majority of methylated sites in the human genome and their methylated state is necessary for this repetitive DNA to function properly and to maintain genome integrity. Furthermore, recent advances highlight the emerging role of these sequences in regulating the functions of the human genome and its variability during evolution, among individuals, or in disease susceptibility. In addition, a number of inherited rare diseases are directly linked to the alteration of some of these repetitive DNA sequences, either through changes in the organization or size of the tandem repeat arrays or through mutations in genes encoding chromatin modifiers involved in the epigenetic regulation of these elements. Although largely overlooked so far in the functional annotation of the human genome, satellite elements play key roles in its architectural and topological organization. This includes functions as boundary elements delimitating functional domains or assembly of repressive nuclear compartments, with local or distal impact on gene expression. Thus, the consideration of satellite repeats organization and their associated epigenetic landmarks, including DNA methylation (DNAme), will become unavoidable in the near future to fully decipher human phenotypes and associated diseases.

scholarly journals A novel putative microtubule-associated protein is involved in arbuscule development during arbuscular mycorrhiza formation

2021 ◽  
Author(s):  
Tania Ho-Plágaro ◽  
Raúl Huertas ◽  
María I Tamayo-Navarrete ◽  
Elison Blancaflor ◽  
Nuria Gavara ◽  
...  
Keyword(s):  
Plant Root ◽  
Arbuscular Mycorrhizal ◽  
Host Cells ◽  
Root Cells ◽  
Filament Dynamics ◽  
Fungal Structure ◽  
Genes Encoding ◽  
Associated Proteins ◽  
Mycorrhizal Development

Abstract The formation of arbuscular mycorrhizal (AM) symbiosis requires plant root host cells to undergo major structural and functional reprogramming in order to house the highly branched AM fungal structure for the reciprocal exchange of nutrients. These morphological modifications are associated with cytoskeleton remodelling. However, molecular bases and the role of microtubules (MTs) and actin filament dynamics during AM formation are largely unknown. In this study, the tomato tsb gene, belonging to a Solanaceae group of genes encoding MT-associated proteins for pollen development, was found to be highly expressed in root cells containing arbuscules. At earlier stages of mycorrhizal development, tsb overexpression enhanced the formation of highly developed and transcriptionally active arbuscules, while tsb silencing hampers the formation of mature arbuscules and represses arbuscule functionality. However, at later stages of mycorrhizal colonization, tsb OE roots accumulate fully developed transcriptionally inactive arbuscules, suggesting that the collapse and turnover of arbuscules might be impaired by TSB accumulation. Imaging analysis of the MT cytoskeleton in cortex root cells overexpressing tsb revealed that TSB is involved in MT-bundling. Taken together, our results provide unprecedented insights into the role of novel MT-associated protein in MT rearrangements throughout the different stages of the arbuscule life cycle.

scholarly journals Systems Biology and Bile Acid Signalling in Microbiome-Host Interactions in the Cystic Fibrosis Lung

Antibiotics ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 766
Author(s):  
David F. Woods ◽  
Stephanie Flynn ◽  
Jose A. Caparrós-Martín ◽  
Stephen M. Stick ◽  
F. Jerry Reen ◽  
...  
Keyword(s):  
Cystic Fibrosis ◽  
Bile Acids ◽  
Host Response ◽  
Signal Molecules ◽  
Therapeutic Approaches ◽  
Related Factors ◽  
Host Interactions ◽  
Important Host ◽  
Respiratory Microbiota

The study of the respiratory microbiota has revealed that the lungs of healthy and diseased individuals harbour distinct microbial communities. Imbalances in these communities can contribute to the pathogenesis of lung disease. How these imbalances occur and establish is largely unknown. This review is focused on the genetically inherited condition of Cystic Fibrosis (CF). Understanding the microbial and host-related factors that govern the establishment of chronic CF lung inflammation and pathogen colonisation is essential. Specifically, dissecting the interplay in the inflammation–pathogen–host axis. Bile acids are important host derived and microbially modified signal molecules that have been detected in CF lungs. These bile acids are associated with inflammation and restructuring of the lung microbiota linked to chronicity. This community remodelling involves a switch in the lung microbiota from a high biodiversity/low pathogen state to a low biodiversity/pathogen-dominated state. Bile acids are particularly associated with the dominance of Proteobacterial pathogens. The ability of bile acids to impact directly on both the lung microbiota and the host response offers a unifying principle underpinning the pathogenesis of CF. The modulating role of bile acids in lung microbiota dysbiosis and inflammation could offer new potential targets for designing innovative therapeutic approaches for respiratory disease.

scholarly journals A PPR Protein ACM1 Is Involved in Chloroplast Gene Expression and Early Plastid Development in Arabidopsis

2021 ◽  
Vol 22 (5) ◽  
pp. 2512
Author(s):  
Xinwei Wang ◽  
Yaqi An ◽  
Ye Li ◽  
Jianwei Xiao
Keyword(s):  
Fluorescent Protein ◽  
Chloroplast Development ◽  
Nuclear Gene ◽  
Pentatricopeptide Repeat ◽  
Plastid Development ◽  
Chloroplast Gene Expression ◽  
Knock Out ◽  
Rnai Line ◽  
Ppr Protein ◽  
P Type

Chloroplasts cannot develop normally without the coordinated action of various proteins and signaling connections between the nucleus and the chloroplast genome. Many questions regarding these processes remain unanswered. Here, we report a novel P-type pentatricopeptide repeat (PPR) factor, named Albino Cotyledon Mutant1 (ACM1), which is encoded by a nuclear gene and involved in chloroplast development. Knock-down of ACM1 transgenic plants displayed albino cotyledons but normal true leaves, while knock-out of the ACM1 gene in seedlings was lethal. Fluorescent protein analysis showed that ACM1 was specifically localized within chloroplasts. PEP-dependent plastid transcript levels and splicing efficiency of several group II introns were seriously affected in cotyledons in the RNAi line. Furthermore, denaturing gel electrophoresis and Western blot experiments showed that the accumulation of chloroplast ribosomes was probably damaged. Collectively, our results indicate ACM1 is indispensable in early chloroplast development in Arabidopsis cotyledons.

scholarly journals The Role of Cdh1p in Maintaining Genomic Stability in Budding Yeast

Genetics ◽  
2003 ◽  
Vol 165 (2) ◽  
pp. 489-503 ◽  
Author(s):  
Karen E Ross ◽  
Orna Cohen-Fix
Keyword(s):  
Cell Cycle ◽  
Chromosome Segregation ◽  
Spindle Assembly Checkpoint ◽  
Chromosome Loss ◽  
Cyclin Dependent Kinase ◽  
Anaphase Promoting Complex ◽  
Growth Defects ◽  
Genes Encoding ◽  
Specificity Factor

Abstract Cdh1p, a substrate specificity factor for the cell cycle-regulated ubiquitin ligase, the anaphase-promoting complex/cyclosome (APC/C), promotes exit from mitosis by directing the degradation of a number of proteins, including the mitotic cyclins. Here we present evidence that Cdh1p activity at the M/G1 transition is important not only for mitotic exit but also for high-fidelity chromosome segregation in the subsequent cell cycle. CDH1 showed genetic interactions with MAD2 and PDS1, genes encoding components of the mitotic spindle assembly checkpoint that acts at metaphase to prevent premature chromosome segregation. Unlike cdh1Δ and mad2Δ single mutants, the mad2Δ cdh1Δ double mutant grew slowly and exhibited high rates of chromosome and plasmid loss. Simultaneous deletion of PDS1 and CDH1 caused extensive chromosome missegregation and cell death. Our data suggest that at least part of the chromosome loss can be attributed to kinetochore/spindle problems. Our data further suggest that Cdh1p and Sic1p, a Cdc28p/Clb inhibitor, have overlapping as well as nonoverlapping roles in ensuring proper chromosome segregation. The severe growth defects of both mad2Δ cdh1Δ and pds1Δ cdh1Δ strains were rescued by overexpressing Swe1p, a G2/M inhibitor of the cyclin-dependent kinase, Cdc28p/Clb. We propose that the failure to degrade cyclins at the end of mitosis leaves cdh1Δ mutant strains with abnormal Cdc28p/Clb activity that interferes with proper chromosome segregation.

scholarly journals Potential Role of Phospholipases in Virulence and Fungal Pathogenesis

2000 ◽  
Vol 13 (1) ◽  
pp. 122-143 ◽  
Author(s):  
Mahmoud A. Ghannoum
Keyword(s):  
Virulence Factor ◽  
Cell Damage ◽  
Pathogenic Fungi ◽  
Microbial Pathogens ◽  
Immunogold Electron Microscopy ◽  
Lytic Enzymes ◽  
Fungal Virulence ◽  
Phospholipase B ◽  
Genes Encoding

SUMMARY Microbial pathogens use a number of genetic strategies to invade the host and cause infection. These common themes are found throughout microbial systems. Secretion of enzymes, such as phospholipase, has been proposed as one of these themes that are used by bacteria, parasites, and pathogenic fungi. The role of extracellular phospholipase as a potential virulence factor in pathogenic fungi, including Candida albicans, Cryptococcus neoformans, and Aspergillus, has gained credence recently. In this review, data implicating phospholipase as a virulence factor in C. albicans, Candida glabrata, C. neoformans, and A. fumigatus are presented. A detailed description of the molecular and biochemical approaches used to more definitively delineate the role of phospholipase in the virulence of C. albicans is also covered. These approaches resulted in cloning of three genes encoding candidal phospholipases (caPLP1, caPLB2, and PLD). By using targeted gene disruption, C. albicans null mutants that failed to secrete phospholipase B, encoded by caPLB1, were constructed. When these isogenic strain pairs were tested in two clinically relevant murine models of candidiasis, deletion of caPLB1 was shown to lead to attenuation of candidal virulence. Importantly, immunogold electron microscopy studies showed that C. albicans secretes this enzyme during the infectious process. These data indicate that phospholipase B is essential for candidal virulence. Although the mechanism(s) through which phospholipase modulates fungal virulence is still under investigations, early data suggest that direct host cell damage and lysis are the main mechanisms contributing to fungal virulence. Since the importance of phospholipases in fungal virulence is already known, the next challenge will be to utilize these lytic enzymes as therapeutic and diagnostic targets.

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