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Zuo L, Zhang S, Liu Y, Huang Y, Yang M, Wang J. The Reason for Growth Inhibition of Ulmus pumila 'Jinye': Lower Resistance and Abnormal Development of Chloroplasts Slow Down the Accumulation of Energy. Int J Mol Sci 2019; 20:ijms20174227. [PMID: 31470529 PMCID: PMC6747506 DOI: 10.3390/ijms20174227] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2019] [Revised: 08/21/2019] [Accepted: 08/22/2019] [Indexed: 11/16/2022] Open
Abstract
Ulmus pumila 'Jinye', the colorful leaf mutant of Ulmus pumila L., is widely used in landscaping. In common with most leaf color mutants, U. pumila 'Jinye' exhibits growth inhibition. In this study, U. pumila L. and U. pumila 'Jinye' were used to elucidate the reasons for growth inhibition at the physiological, cellular microstructural, and transcriptional levels. The results showed that the pigment (chlorophyll a, chlorophyll b, and carotenoids) content of U. pumila L. was higher than that of U. pumila 'Jinye', whereas U. pumila 'Jinye' had a higher proportion of carotenoids, which may be the cause of the yellow leaves. Examination of the cell microstructure and RNA sequencing analysis showed that the leaf color and growth inhibition were mainly due to the following reasons: first, there were differences in the structure of the thylakoid grana layer. U. pumila L. has a normal chloroplast structure and clear thylakoid grana slice layer structure, with ordered and compact thylakoids. However, U. pumila 'Jinye' exhibited the grana lamella stacking failures and fewer thylakoid grana slice layers. As the pigment carrier and the key location for photosynthesis, the close stacking of thylakoid grana could combine more chlorophyll and promote efficient electron transfer promoting the photosynthesis reaction. In addition, U. pumila 'Jinye' had a lower capacity for light energy absorption, transformation, and transportation, carbon dioxide (CO2) fixation, lipopolysaccharide biosynthesis, auxin synthesis, and protein transport. The genes related to respiration and starch consumption were higher than those of U. pumila L., which indicated less energy accumulation caused the growth inhibition of U. pumila 'Jinye'. Finally, compared with U. pumila 'Jinye', the transcription of genes related to stress resistance all showed an upward trend in U. pumila L. That is to say, U. pumila L. had a greater ability to resist adversity, which could maintain the stability of the intracellular environment and maintain normal progress of physiological metabolism. However, U. pumila 'Jinye' was more susceptible to changes in the external environment, which affected normal physiological metabolism. This study provides evidence for the main cause of growth inhibition in U. pumila 'Jinye', information for future cultivation, and information on the mutation mechanism for the breeding of colored leaf trees.
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Affiliation(s)
- Lihui Zuo
- Institute of Forest Biotechnology, Forestry College, Agricultural University of Hebei, Baoding 071000, China
- Hebei Key Laboratory for Tree Genetic Resources and Forest Protection, Baoding 071000, China
- College of Landscape and Ecological Engineering, Hebei University of Engineering, Handan 056000, China
| | - Shuang Zhang
- Institute of Forest Biotechnology, Forestry College, Agricultural University of Hebei, Baoding 071000, China
- College of Landscape and Ecological Engineering, Hebei University of Engineering, Handan 056000, China
| | - Yichao Liu
- Institute of Forest Biotechnology, Forestry College, Agricultural University of Hebei, Baoding 071000, China
- Hebei Forestry Research Institute, Shijiazhuang 050000, China
| | - Yinran Huang
- Hebei Forestry Research Institute, Shijiazhuang 050000, China
| | - Minsheng Yang
- Institute of Forest Biotechnology, Forestry College, Agricultural University of Hebei, Baoding 071000, China.
- Hebei Key Laboratory for Tree Genetic Resources and Forest Protection, Baoding 071000, China.
| | - Jinmao Wang
- Institute of Forest Biotechnology, Forestry College, Agricultural University of Hebei, Baoding 071000, China.
- Hebei Key Laboratory for Tree Genetic Resources and Forest Protection, Baoding 071000, China.
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Rea G, Antonacci A, Lambreva MD, Mattoo AK. Features of cues and processes during chloroplast-mediated retrograde signaling in the alga Chlamydomonas. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2018; 272:193-206. [PMID: 29807591 DOI: 10.1016/j.plantsci.2018.04.020] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2017] [Revised: 04/04/2018] [Accepted: 04/23/2018] [Indexed: 06/08/2023]
Abstract
Retrograde signaling is an intracellular communication process defined by cues generated in chloroplast and mitochondria which traverse membranes to their destination in the nucleus in order to regulate nuclear gene expression and protein synthesis. The coding and decoding of such organellar message(s) involve gene medleys and metabolic components about which more is known in higher plants than the unicellular organisms such as algae. Chlamydomonas reinhardtii is an oxygenic microalgal model for genetic and physiological studies. It harbors a single chloroplast and is amenable for generating mutants. The focus of this review is on studies that delineate retrograde signaling in Chlamydomonas vis a vis higher plants. Thus, communication networks between chloroplast and nucleus involving photosynthesis- and ROS-generated signals, functional tetrapyrrole biosynthesis intermediates, and Ca2+-signaling that modulate nuclear gene expression in this alga are discussed. Conceptually, different signaling components converge to regulate either the same or functionally-overlapping gene products.
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Affiliation(s)
- Giuseppina Rea
- Institute of Crystallography, National Research Council of Italy, Via Salaria Km 29, 3 00015 Monterotondo Scalo, Rome, Italy
| | - Amina Antonacci
- Institute of Crystallography, National Research Council of Italy, Via Salaria Km 29, 3 00015 Monterotondo Scalo, Rome, Italy
| | - Maya D Lambreva
- Institute of Crystallography, National Research Council of Italy, Via Salaria Km 29, 3 00015 Monterotondo Scalo, Rome, Italy
| | - Autar K Mattoo
- The Henry A Wallace Agricultural Research Centre, U.S. Department of Agriculture, Sustainable Agricultural Systems Laboratory, Beltsville, MD 20705, USA.
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Karpinska B, Alomrani SO, Foyer CH. Inhibitor-induced oxidation of the nucleus and cytosol in Arabidopsis thaliana: implications for organelle to nucleus retrograde signalling. Philos Trans R Soc Lond B Biol Sci 2018; 372:rstb.2016.0392. [PMID: 28808105 PMCID: PMC5566886 DOI: 10.1098/rstb.2016.0392] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/01/2017] [Indexed: 11/14/2022] Open
Abstract
Concepts of organelle-to-nucleus signalling pathways are largely based on genetic screens involving inhibitors of chloroplast and mitochondrial functions such as norflurazon, lincomycin (LINC), antimycin A (ANT) and salicylhydroxamic acid. These inhibitors favour enhanced cellular oxidation, but their precise effects on the cellular redox state are unknown. Using the in vivo reduction–oxidation (redox) reporter, roGFP2, inhibitor-induced changes in the glutathione redox potentials of the nuclei and cytosol were measured in Arabidopsis thaliana root, epidermal and stomatal guard cells, together with the expression of nuclear-encoded chloroplast and mitochondrial marker genes. All the chloroplast and mitochondrial inhibitors increased the degree of oxidation in the nuclei and cytosol. However, inhibitor-induced oxidation was less marked in stomatal guard cells than in epidermal or root cells. Moreover, LINC and ANT caused a greater oxidation of guard cell nuclei than the cytosol. Chloroplast and mitochondrial inhibitors significantly decreased the abundance of LHCA1 and LHCB1 transcripts. The levels of WHY1, WHY3 and LEA5 transcripts were increased in the presence of inhibitors. Chloroplast inhibitors decreased AOXA1 mRNA levels, while mitochondrial inhibitors had the opposite effect. Inhibitors that are used to characterize retrograde signalling pathways therefore have similar general effects on cellular redox state and gene expression. This article is part of the themed issue ‘Enhancing photosynthesis in crop plants: targets for improvement’.
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Affiliation(s)
- Barbara Karpinska
- Centre for Plant Sciences, School of Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Sarah Owdah Alomrani
- Centre for Plant Sciences, School of Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Christine H Foyer
- Centre for Plant Sciences, School of Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
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Liu J, Yang J, Bi H, Zhang P. Why mosaic? Gene expression profiling of African cassava mosaic virus-infected cassava reveals the effect of chlorophyll degradation on symptom development. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2014; 56:122-32. [PMID: 24237761 DOI: 10.1111/jipb.12133] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2013] [Accepted: 11/11/2013] [Indexed: 05/18/2023]
Abstract
Cassava mosaic disease, caused by cassava begomoviruses, is the most serious disease for cassava in Africa. However, the pathogenesis of this disease is poorly understood. We employed high throughput digital gene expression profiling based on the Illumina Solexa sequencing technology to investigate the global transcriptional response of cassava to African cassava mosaic virus infection. We found that 3,210 genes were differentially expressed in virus-infected cassava leaves. Gene ontology term and Kyoto Encyclopedia of Genes and Genomes pathway analysis indicated that genes implicated in photosynthesis were most affected, consistent with the chlorotic symptoms observed in infected leaves. The upregulation of chlorophyll degradation genes, including the genes encoding chlorophyllase, pheophytinase, and pheophorbide a oxygenase, and downregulation of genes encoding the major apoproteins in light-harvesting complex II were confirmed by qRT-PCR. These findings, together with the reduction of chlorophyll b content and fewer grana stacks in the infected leaf cells, reveal that the degradation of chlorophyll plays an important role in African cassava mosaic virus symptom development. This study will provide a road map for future investigations into viral pathogenesis.
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Affiliation(s)
- Jiao Liu
- Shanghai Chenshan Plant Science Research Center, the Chinese Academy of Sciences, Chenshan Botanical Garden, Shanghai, 201602, China; National Key Laboratory of Plant Molecular Genetics and National Center for Plant Gene Research (Shanghai), Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, the Chinese Academy of Science, Shanghai, 200032, China
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5
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Kim C, Apel K. 1O2-mediated and EXECUTER-dependent retrograde plastid-to-nucleus signaling in norflurazon-treated seedlings of Arabidopsis thaliana. MOLECULAR PLANT 2013; 6:1580-91. [PMID: 23376773 PMCID: PMC3842135 DOI: 10.1093/mp/sst020] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2013] [Accepted: 01/20/2013] [Indexed: 05/18/2023]
Abstract
Chloroplast development depends on the synthesis and import of a large number of nuclear-encoded proteins. The synthesis of some of these proteins is affected by the functional state of the plastid via a process known as retrograde signaling. Retrograde plastid-to-nucleus signaling has been often characterized in seedlings of Arabidopsis thaliana exposed to norflurazon (NF), an inhibitor of carotenoid biosynthesis. Results of this work suggested that, throughout seedling development, a factor is released from the plastid to the cytoplasm that indicates a perturbation of plastid homeostasis and represses nuclear genes required for normal chloroplast development. The identity of this factor is still under debate. Reactive oxygen species (ROS) were among the candidates discussed as possible retrograde signals in NF-treated plants. In the present work, this proposed role of ROS has been analyzed. In seedlings grown from the very beginning in the presence of NF, ROS-dependent signaling was not detectable, whereas, in seedlings first exposed to NF after light-dependent chloroplast formation had been completed, enhanced ROS production occurred and, among others, (1)O2-mediated and EXECUTER-dependent retrograde signaling was induced. Hence, depending on the developmental stage at which plants are exposed to NF, different retrograde signaling pathways may be activated, some of which are also active in non-treated plants under light stress.
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Affiliation(s)
| | - Klaus Apel
- To whom correspondence should be addressed. E-mail , tel. +1-607-2797734
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Estavillo GM, Chan KX, Phua SY, Pogson BJ. Reconsidering the nature and mode of action of metabolite retrograde signals from the chloroplast. FRONTIERS IN PLANT SCIENCE 2012; 3:300. [PMID: 23316207 PMCID: PMC3539676 DOI: 10.3389/fpls.2012.00300] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2012] [Accepted: 12/12/2012] [Indexed: 05/18/2023]
Abstract
Plant organelles produce retrograde signals to alter nuclear gene expression in order to coordinate their biogenesis, maintain homeostasis, or optimize their performance under adverse conditions. Many signals of different chemical nature have been described in the past decades, including chlorophyll intermediates, reactive oxygen species (ROS), and adenosine derivatives. While the effects of retrograde signaling on gene expression are well understood, the initiation and transport of the signals and their mode of action have either not been resolved, or are a matter of speculation. Moreover, retrograde signaling should be considered as part of a broader cellular network, instead of as separate pathways, required to adjust to changing physiologically relevant conditions. Here we summarize current plastid retrograde signaling models in plants, with a focus on new signaling pathways, SAL1-PAP, methylerythritol cyclodiphosphate (MEcPP), and β-cyclocitral (β-CC), and outline missing links or future areas of research that we believe need to be addressed to have a better understanding of plant intracellular signaling networks.
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Affiliation(s)
| | | | | | - Barry J. Pogson
- *Correspondence: Barry J. Pogson, ARC Centre of Excellence in Plant Energy of Biology, Research School of Biology, The Australian National University, Canberra, ACT 0200, Australia. e-mail:
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Liere K, Weihe A, Börner T. The transcription machineries of plant mitochondria and chloroplasts: Composition, function, and regulation. JOURNAL OF PLANT PHYSIOLOGY 2011; 168:1345-60. [PMID: 21316793 DOI: 10.1016/j.jplph.2011.01.005] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2010] [Revised: 01/07/2011] [Accepted: 01/10/2011] [Indexed: 05/04/2023]
Abstract
Although genomes of mitochondria and plastids are very small compared to those of their bacterial ancestors, the transcription machineries of these organelles are of surprising complexity. With respect to the number of different RNA polymerases per organelle, the extremes are represented on one hand by chloroplasts of eudicots which use one bacterial-type RNA polymerase and two phage-type RNA polymerases to transcribe their genes, and on the other hand by Physcomitrella possessing three mitochondrial RNA polymerases of the phage type. Transcription of genes/operons is often driven by multiple promoters in both organelles. This review describes the principle components of the transcription machineries (RNA polymerases, transcription factors, promoters) and the division of labor between the different RNA polymerases. While regulation of transcription in mitochondria seems to be only of limited importance, the plastid genes of higher plants respond to exogenous and endogenous cues rather individually by altering their transcriptional activities.
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Affiliation(s)
- Karsten Liere
- Institut für Biologie/Genetik, Humboldt-Universität zu Berlin, Chausseestrasse 117, Berlin, Germany
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8
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On the origin of chloroplasts, import mechanisms of chloroplast-targeted proteins, and loss of photosynthetic ability — review. Folia Microbiol (Praha) 2009; 54:303-21. [DOI: 10.1007/s12223-009-0048-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2008] [Revised: 03/31/2009] [Indexed: 10/20/2022]
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9
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Koussevitzky S, Nott A, Mockler TC, Hong F, Sachetto-Martins G, Surpin M, Lim J, Mittler R, Chory J. Signals from chloroplasts converge to regulate nuclear gene expression. Science 2007; 316:715-9. [PMID: 17395793 DOI: 10.1126/science.1140516] [Citation(s) in RCA: 571] [Impact Index Per Article: 33.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
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 genes.
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Affiliation(s)
- Shai Koussevitzky
- Howard Hughes Medical Institute, Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA
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10
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Transcription and transcriptional regulation in plastids. CELL AND MOLECULAR BIOLOGY OF PLASTIDS 2007. [DOI: 10.1007/4735_2007_0232] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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11
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Abstract
The importance of chlorophyll (Chl) to the process of photosynthesis is obvious, and there is clear evidence that the regulation of Chl biosynthesis has a significant role in the regulation of assembly of the photosynthetic apparatus. The understanding of Chl biosynthesis has rapidly advanced in recent years. The identification of genetic loci associated with each of the biochemical steps has been accompanied by a greater appreciation of the role of Chl biosynthesis intermediates in intracellular signaling. The purpose of this review is to provide a source of information for all the steps in Chl and bacteriochlorophyll a biosynthesis, with an emphasis on steps that are believed to be key regulation points.
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Affiliation(s)
- David W Bollivar
- Department of Biology, Illinois Wesleyan University, Bloomington, IL 61702-2900, USA.
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12
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Shao N, Vallon O, Dent R, Niyogi KK, Beck CF. Defects in the cytochrome b6/f complex prevent light-induced expression of nuclear genes involved in chlorophyll biosynthesis. PLANT PHYSIOLOGY 2006; 141:1128-37. [PMID: 16679422 PMCID: PMC1489919 DOI: 10.1104/pp.106.081059] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2006] [Revised: 04/25/2006] [Accepted: 04/25/2006] [Indexed: 05/09/2023]
Abstract
Mutants with defects in the cytochrome (cyt) b6/f complex were analyzed for their effect on the expression of a subgroup of nuclear genes encoding plastid-localized enzymes participating in chlorophyll biosynthesis. Their defects ranged from complete loss of the cytb6/f complex to point mutations affecting specifically the quinone-binding QO site. In these seven mutants, light induction of the tetrapyrrole biosynthetic genes was either abolished or strongly reduced. In contrast, a normal induction of chlorophyll biosynthesis genes was observed in mutants with defects in photosystem II, photosystem I, or plastocyanin, or in wild-type cells treated with 3-(3'4'-dichlorophenyl)-1,1-dimethylurea or 2,5-dibromo-3-methyl-6-isopropyl benzoquinone. We conclude that the redox state of the plastoquinone pool does not control light induction of these chlorophyll biosynthetic genes. The signal that affects expression of the nuclear genes appears to solely depend on the integrity of the cytb6/f complex QO site. Since light induction of these genes in Chlamydomonas has recently been shown to involve the blue light receptor phototropin, the results suggest that cytb6/f activity regulates a plastid-derived factor required for their expression. This signaling pathway differs from that which regulates state transitions, since mutant stt7, lacking a protein kinase involved in phosphorylation of the light-harvesting complex II, was not altered in the expression of the chlorophyll biosynthetic genes.
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Affiliation(s)
- Ning Shao
- Institut fuer Biologie III, Universitaet Freiburg, D-79104 Freiburg, Germany
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Beck CF. Signaling pathways from the chloroplast to the nucleus. PLANTA 2005; 222:743-56. [PMID: 16231154 DOI: 10.1007/s00425-005-0021-2] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2005] [Accepted: 05/04/2005] [Indexed: 05/04/2023]
Abstract
Genetic and physiological studies have to-date revealed evidence for five signaling pathways by which the chloroplast exerts retrograde control over nuclear genes. One of these pathways is dependent on product(s) of plastid protein synthesis, for another the signal is singlet oxygen, a third employs chloroplast-generated hydrogen peroxide, a fourth is controlled by the redox state of the photosynthetic electron transport chain, and a fifth involves intermediates and possibly proteins of tetrapyrrole biosynthesis. These five pathways may be part of a complex signaling network that links the functional and physiological state of the chloroplast to the nucleus. Mutants defective in various steps of photosynthesis reveal a surprising diversity in nuclear responses suggesting the existence of a complex signaling network.
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Affiliation(s)
- Christoph F Beck
- Institute of Biology III, University of Freiburg, Schaenzlestrasse 1, 79104, Freiburg, Germany.
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Vasileuskaya Z, Oster U, Beck CF. Mg-protoporphyrin IX and heme control HEMA, the gene encoding the first specific step of tetrapyrrole biosynthesis, in Chlamydomonas reinhardtii. EUKARYOTIC CELL 2005; 4:1620-8. [PMID: 16215169 PMCID: PMC1265898 DOI: 10.1128/ec.4.10.1620-1628.2005] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2005] [Accepted: 07/28/2005] [Indexed: 11/20/2022]
Abstract
HEMA encodes glutamyl-tRNA reductase (GluTR), which catalyzes the first step specific for tetrapyrrole biosynthesis in plants, archaea, and most eubacteria. In higher plants, GluTR is feedback inhibited by heme and intermediates of chlorophyll biosynthesis. It plays a key role in controlling flux through the tetrapyrrole biosynthetic pathway. This enzyme, which in Chlamydomonas reinhardtii is encoded by a single gene (HEMA), exhibits homology to GluTRs of higher plants and cyanobacteria. HEMA mRNA accumulation was inducible not only by light but also by treatment of dark-adapted cells with Mg-protoporphyrin IX (MgProto) or hemin. The specificity of these tetrapyrroles as inducers was demonstrated by the absence of induction observed upon the feeding of protoporphyrin IX, the precursor of both heme and MgProto, or chlorophyllide. The HEMA mRNA accumulation following treatment of cells with light and hemin was accompanied by increased amounts of GluTR. However, the feeding of MgProto did not suggest a role for Mg-tetrapyrroles in posttranscriptional regulation. The induction by light but not that by the tetrapyrroles was prevented by inhibition of cytoplasmic protein synthesis. Since MgProto is synthesized exclusively in plastids and heme is synthesized in plastids and mitochondria, the data suggest a role of these compounds as organellar signals that control expression of the nuclear HEMA gene.
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Affiliation(s)
- Zinaida Vasileuskaya
- University of Freiburg, Institute of Biology III, Schaenzlestrasse 1, D-79104 Freiburg, Germany
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Borza T, Popescu CE, Lee RW. Multiple metabolic roles for the nonphotosynthetic plastid of the green alga Prototheca wickerhamii. EUKARYOTIC CELL 2005; 4:253-61. [PMID: 15701787 PMCID: PMC549340 DOI: 10.1128/ec.4.2.253-261.2005] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The presence of plastids in diverse eukaryotic lineages that have lost the capacity for photosynthesis is well documented. The metabolic functions of such organelles, however, are poorly understood except in the case of the apicoplast in the Apicomplexa, a group of intracellular parasites including Plasmodium falciparum, and the plastid of the green alga Helicosporidium sp., a parasite for which the only host-free stage identified in nature so far is represented by cysts. As a first step in the reconstruction of plastid functions in a nonphotosynthetic, predominantly free-living organism, we searched for expressed sequence tags (ESTs) that correspond to nucleus-encoded plastid-targeted polypeptides in the green alga Prototheca wickerhamii. From 3,856 ESTs, we found that 71 unique sequences (235 ESTs) correspond to different nucleus-encoded putatively plastid-targeted polypeptides. The identified proteins predict that carbohydrate, amino acid, lipid, tetrapyrrole, and isoprenoid metabolism as well as de novo purine biosynthesis and oxidoreductive processes take place in the plastid of P. wickerhamii. Mg-protoporphyrin accumulation and, therefore, plastid-to-nucleus signaling might also occur in this nonphotosynthetic organism, as we identified a transcript which encodes subunit I of Mg-chelatase, the enzyme which catalyzes the first committed step in chlorophyll synthesis. Our data indicate a far more complex metabolism in P. wickerhamii's plastid compared with the metabolic pathways predicted to be located in the apicoplast of P. falciparum and the plastid of Helicosporidium sp.
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Affiliation(s)
- Tudor Borza
- Department of Biology, Dalhousie University, Halifax, Nova Scotia, B3H 4J1, Canada
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Falciatore A, Merendino L, Barneche F, Ceol M, Meskauskiene R, Apel K, Rochaix JD. The FLP proteins act as regulators of chlorophyll synthesis in response to light and plastid signals in Chlamydomonas. Genes Dev 2005; 19:176-87. [PMID: 15630026 PMCID: PMC540235 DOI: 10.1101/gad.321305] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
In photosynthetic organisms the accumulation of harmful photodynamic chlorophyll precursors is prevented because of the tight regulation of the tetrapyrrole pathway. FLU is one of the regulatory factors involved in this process in land plants. We have examined the function of a Flu-like gene (FLP) from Chlamydomonas that gives rise to two FLP transcripts through alternative splicing. These transcripts are translated into a short and a long protein that differ by only 12 amino acids but that interact differently with glutamyl-tRNA reductase, an enzyme involved in an early step of the chlorophyll biosynthetic pathway. Expression of FLPs is light-regulated at the level of RNA accumulation and splicing and is altered by mutations affecting the pathway. The relative levels of the long and short forms of FLP can be correlated with the accumulation of specific porphyrin intermediates, some of which have been implicated in a signaling chain from the chloroplast to the nucleus. Reciprocally, reduction of the FLP proteins by RNA interference leads to the accumulation of several porphyrin intermediates and to photobleaching when cells are transferred from the dark to the light. Thus the FLP proteins act as regulators of chlorophyll synthesis, and their expression is controlled by light and plastid signals.
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Affiliation(s)
- Angela Falciatore
- Department of Molecular Biology, University of Geneva, 1211 Geneva, Switzerland
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Vasileuskaya Z, Oster U, Beck CF. Involvement of tetrapyrroles in inter-organellar signaling in plants and algae. PHOTOSYNTHESIS RESEARCH 2004; 82:289-99. [PMID: 16143841 DOI: 10.1007/s11120-004-2160-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2004] [Accepted: 07/21/2004] [Indexed: 05/04/2023]
Abstract
For the assembly of a functional chloroplast, the coordinated expression of genes distributed between nucleus and chloroplasts is a prerequisite. While the nucleus plays an undisputed dominant role in controling biogenesis and functioning of chloroplasts, plastidic signals appear to control the expression of a subset of nuclear genes; the majority of which encodes chloroplast constituents. Tetrapyrrole biosynthesis intermediates are attractive candidates for one type of plastidic signal ever since an involvement of Mg-porphyrins in signaling from chloroplast to nucleus was first demonstrated in Chlamydomonas reinhardtii. Since then, Mg-protoporphyrin IX has been shown to exert a regulatory function on nuclear genes in higher plants as well. Here we review evidence for the role played by tetrapyrroles in inter-organellar communication. We also report on a screening for nuclear genes that may be subject to regulation by tetrapyrroles. This revealed that (i) >HEMA, the gene encoding the first enzyme specific for porphyrin biosynthesis is induced by Mg-protoporphyrin IX, (ii) several nuclear HSP70 genes are regulated by tetrapyrroles. Members of the gene family induced by the feeding of Mg-rotoporphyrin IX encode chaperones located in either the chloroplast or the cytosol. These results point to an important role of Mg-tetrapyrroles as plastidic signal in controling the initial step of porphyrin biosynthesis, and the synthesis of chaperones involved in protein folding in cytosol/stroma, protein transport into organelles, and the stress response.
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Affiliation(s)
- Zinaida Vasileuskaya
- Institut fuer Biologie III, Albert-Ludwigs-Universitaet, Schaenzlestrasse 1, 79104, Freiburg, Germany,
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