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Sinha N, Eirich J, Finkemeier I, Grimm B. Glutamate 1-semialdehyde aminotransferase is connected to GluTR by GluTR-binding protein and contributes to the rate-limiting step of 5-aminolevulinic acid synthesis. THE PLANT CELL 2022; 34:4623-4640. [PMID: 35972388 PMCID: PMC9614494 DOI: 10.1093/plcell/koac237] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Accepted: 07/28/2022] [Indexed: 06/01/2023]
Abstract
Tetrapyrroles play fundamental roles in crucial processes including photosynthesis, respiration, and catalysis. In plants, 5-aminolevulinic acid (ALA) is the common precursor of tetrapyrroles. ALA is synthesized from activated glutamate by the enzymes glutamyl-tRNA reductase (GluTR) and glutamate-1-semialdehyde aminotransferase (GSAAT). ALA synthesis is recognized as the rate-limiting step in this pathway. We aimed to explore the contribution of GSAAT to the control of ALA synthesis and the formation of a protein complex with GluTR. In Arabidopsis thaliana, two genes encode GSAAT isoforms: GSA1 and GSA2. A comparison of two GSA knockout mutants with the wild-type revealed the correlation of reduced GSAAT activity and ALA-synthesizing capacity in leaves with lower chlorophyll content. Growth and green pigmentation were more severely impaired in gsa2 than in gsa1, indicating the predominant role of GSAAT2 in ALA synthesis. Interestingly, GluTR accumulated to higher levels in gsa2 than in the wild-type and was mainly associated with the plastid membrane. We propose that the GSAAT content modulates the amount of soluble GluTR available for ALA synthesis. Several different biochemical approaches revealed the GSAAT-GluTR interaction through the assistance of GluTR-binding protein (GBP). A modeled structure of the tripartite protein complex indicated that GBP mediates the stable association of GluTR and GSAAT for adequate ALA synthesis.
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Affiliation(s)
- Neha Sinha
- Institute of Biology/Plant Physiology, Humboldt-University Berlin, 10115 Berlin, Germany
| | - Jürgen Eirich
- Institute for Plant Biology and Biotechnology, Plant Physiology, Westfälische Wilhelms-Universität, 48149 Muenster, Germany
| | - Iris Finkemeier
- Institute for Plant Biology and Biotechnology, Plant Physiology, Westfälische Wilhelms-Universität, 48149 Muenster, Germany
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2
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Adhikari ND, Simko I, Mou B. Phenomic and Physiological Analysis of Salinity Effects on Lettuce. SENSORS (BASEL, SWITZERLAND) 2019; 19:E4814. [PMID: 31694293 PMCID: PMC6864466 DOI: 10.3390/s19214814] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/05/2019] [Revised: 10/23/2019] [Accepted: 11/01/2019] [Indexed: 01/08/2023]
Abstract
Salinity is a rising concern in many lettuce-growing regions. Lettuce (Lactuca sativa L.) is sensitive to salinity, which reduces plant biomass, and causes leaf burn and early senescence. We sought to identify physiological traits important in salt tolerance that allows lettuce adaptation to high salinity while maintaining its productivity. Based on previous salinity tolerance studies, one sensitive and one tolerant genotype each was selected from crisphead, butterhead, and romaine, as well as leaf types of cultivated lettuce and its wild relative, L. serriola L. Physiological parameters were measured four weeks after transplanting two-day old seedlings into 350 mL volume pots filled with sand, hydrated with Hoagland nutrient solution and grown in a growth chamber. Salinity treatment consisted of gradually increasing concentrations of NaCl and CaCl2 from 0 mM/0 mM at the time of transplanting, to 30 mM/15 mM at the beginning of week three, and maintaining it until harvest. Across the 10 genotypes, leaf area and fresh weight decreased 0-64% and 16-67%, respectively, under salinity compared to the control. Salinity stress increased the chlorophyll index by 4-26% in the cultivated genotypes, while decreasing it by 5-14% in the two wild accessions. Tolerant lines less affected by elevated salinity were characterized by high values of the chlorophyll fluorescence parameters Fv/Fm and instantaneous photosystem II quantum yield (QY), and lower leaf transpiration.
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Affiliation(s)
- Neil D. Adhikari
- Crop Improvement and Protection Research Unit, United States Department of Agriculture, Agricultural Research Service, Salinas, CA 93905, USA;
| | | | - Beiquan Mou
- Crop Improvement and Protection Research Unit, United States Department of Agriculture, Agricultural Research Service, Salinas, CA 93905, USA;
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3
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iTRAQ-Based Quantitative Proteomic Analysis of a Toxigenic Dinoflagellate Alexandrium catenella at Different Stages of Toxin Biosynthesis during the Cell Cycle. Mar Drugs 2018; 16:md16120491. [PMID: 30544585 PMCID: PMC6315610 DOI: 10.3390/md16120491] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2018] [Revised: 12/02/2018] [Accepted: 12/04/2018] [Indexed: 01/15/2023] Open
Abstract
Paralytic shellfish toxins (PSTs) are a group of potent neurotoxic alkaloids that are produced mainly by marine dinoflagellates. PST biosynthesis in dinoflagellates is a discontinuous process that is coupled to the cell cycle. However, little is known about the molecular mechanism underlying this association. Here, we compared global protein expression profiles of a toxigenic dinoflagellate, Alexandrium catenella, collected at four different stages of toxin biosynthesis during the cell cycle, using an isobaric tags for relative and absolute quantification (iTRAQ)-based quantitative proteomic approach. The results showed that toxin biosynthesis occurred mainly in the G1 phase, especially the late G1 phase. In total, 7232 proteins were confidently identified, and 210 proteins exhibited differential expression among the four stages. Proteins involved in protein translation and photosynthetic pigment biosynthesis were significantly upregulated during toxin biosynthesis, indicating close associations among the three processes. Nine toxin-related proteins were detected, and two core toxin biosynthesis proteins, namely, sxtA and sxtI, were identified for the first time in dinoflagellates. Among these proteins, sxtI and ompR were significantly downregulated when toxin biosynthesis stopped, indicating that they played important roles in the regulation of PST biosynthesis. Our study provides new insights into toxin biosynthesis in marine dinoflagellates: nitrogen balance among different biological processes regulates toxin biosynthesis, and that glutamate might play a key modulatory role.
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Ohmiya A, Hirashima M, Yagi M, Tanase K, Yamamizo C. Identification of genes associated with chlorophyll accumulation in flower petals. PLoS One 2014; 9:e113738. [PMID: 25470367 PMCID: PMC4254739 DOI: 10.1371/journal.pone.0113738] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2014] [Accepted: 10/29/2014] [Indexed: 11/18/2022] Open
Abstract
Plants have an ability to prevent chlorophyll accumulation, which would mask the bright flower color, in their petals. In contrast, leaves contain substantial amounts of chlorophyll, as it is essential for photosynthesis. The mechanisms of organ-specific chlorophyll accumulation are unknown. To identify factors that determine the chlorophyll content in petals, we compared the expression of genes related to chlorophyll metabolism in different stages of non-green (red and white) petals (very low chlorophyll content), pale-green petals (low chlorophyll content), and leaves (high chlorophyll content) of carnation (Dianthus caryophyllus L.). The expression of many genes encoding chlorophyll biosynthesis enzymes, in particular Mg-chelatase, was lower in non-green petals than in leaves. Non-green petals also showed higher expression of genes involved in chlorophyll degradation, including STAY-GREEN gene and pheophytinase. These data suggest that the absence of chlorophylls in carnation petals may be caused by the low rate of chlorophyll biosynthesis and high rate of degradation. Similar results were obtained by the analysis of Arabidopsis microarray data. In carnation, most genes related to chlorophyll biosynthesis were expressed at similar levels in pale-green petals and leaves, whereas the expression of chlorophyll catabolic genes was higher in pale-green petals than in leaves. Therefore, we hypothesize that the difference in chlorophyll content between non-green and pale-green petals is due to different levels of chlorophyll biosynthesis. Our study provides a basis for future molecular and genetic studies on organ-specific chlorophyll accumulation.
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Affiliation(s)
- Akemi Ohmiya
- National Institute of Floricultural Science, National Agriculture and Food Research Organization, Fujimoto 2-1, Tsukuba, Ibaraki 305-8519, Japan
- * E-mail:
| | - Masumi Hirashima
- National Institute of Floricultural Science, National Agriculture and Food Research Organization, Fujimoto 2-1, Tsukuba, Ibaraki 305-8519, Japan
| | - Masafumi Yagi
- National Institute of Floricultural Science, National Agriculture and Food Research Organization, Fujimoto 2-1, Tsukuba, Ibaraki 305-8519, Japan
| | - Koji Tanase
- National Institute of Floricultural Science, National Agriculture and Food Research Organization, Fujimoto 2-1, Tsukuba, Ibaraki 305-8519, Japan
| | - Chihiro Yamamizo
- National Institute of Floricultural Science, National Agriculture and Food Research Organization, Fujimoto 2-1, Tsukuba, Ibaraki 305-8519, Japan
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5
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Atkins KA, Dodd AN. Circadian regulation of chloroplasts. CURRENT OPINION IN PLANT BIOLOGY 2014; 21:43-50. [PMID: 25026538 DOI: 10.1016/j.pbi.2014.06.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2014] [Revised: 06/20/2014] [Accepted: 06/23/2014] [Indexed: 05/08/2023]
Abstract
Circadian rhythms produce a biological measure of time that increases plant performance. The mechanisms that underlie this increase in productivity require investigation to provide information that will underpin future crop improvement. There is a growing body of evidence that a sophisticated signalling network interconnects the circadian oscillator and chloroplasts. We consider this in the context of circadian signalling to chloroplasts and the relationship between retrograde signalling and circadian regulation. We place circadian signalling to chloroplasts by sigma factors within an evolutionary context. We describe selected recent developments in the integration of light and circadian signals that control chloroplast gene expression.
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Affiliation(s)
- Kelly A Atkins
- School of Biological Sciences, Bristol Life Sciences Building, University of Bristol, Bristol BS8 1TQ, UK
| | - Antony N Dodd
- School of Biological Sciences, Bristol Life Sciences Building, University of Bristol, Bristol BS8 1TQ, UK; Cabot Institute, University of Bristol, Bristol BS8 1UJ, UK.
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6
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Braun R, Farré EM, Schurr U, Matsubara S. Effects of light and circadian clock on growth and chlorophyll accumulation of Nannochloropsis gaditana. JOURNAL OF PHYCOLOGY 2014; 50:515-525. [PMID: 26988324 DOI: 10.1111/jpy.12177] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2012] [Accepted: 01/27/2014] [Indexed: 06/05/2023]
Abstract
Circadian clocks synchronize various physiological, metabolic and developmental processes of organisms with specific phases of recurring changes in their environment (e.g. day and night or seasons). Here, we investigated whether the circadian clock plays a role in regulation of growth and chlorophyll (Chl) accumulation in Nannochloropsis gaditana, an oleaginous marine microalga which is considered as a potential feedstock for biofuels and for which a draft genome sequence has been published. Optical density (OD) of N. gaditana culture was monitored at 680 and 735 nm under 12:12 h or 18:6 h light-dark (LD) cycles and after switching to continuous illumination in photobioreactors. In parallel, Chl fluorescence was measured to assess the quantum yield of photosystem II. Furthermore, to test if red- or blue-light photoreceptors are involved in clock entrainment in N. gaditana, some of the experiments were conducted by using only red or blue light. Growth and Chl accumulation were confined to light periods in the LD cycles, increasing more strongly in the first half than in the second half of the light periods. After switching to continuous light, rhythmic oscillations continued (especially for OD680 ) at least in the first 24 h, with a 50% decrease in the capacity to grow and accumulate Chl during the first subjective night. Pronounced free-running oscillations were induced by blue light, but not by red light. In contrast, the photosystem II quantum yield was determined by light conditions. The results indicate interactions between circadian and light regulation of growth and Chl accumulation in N. gaditana.
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Affiliation(s)
- Regina Braun
- IBG-2: Pflanzenwissenschaften, Forschungszentrum Jülich, Jülich, 52425, Germany
| | - Eva M Farré
- Department of Plant Biology, Michigan State University, 612 Wilson Road, East Lansing, Michigan, 48824-1312, USA
| | - Ulrich Schurr
- IBG-2: Pflanzenwissenschaften, Forschungszentrum Jülich, Jülich, 52425, Germany
| | - Shizue Matsubara
- IBG-2: Pflanzenwissenschaften, Forschungszentrum Jülich, Jülich, 52425, Germany
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7
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Dodd AN, Kusakina J, Hall A, Gould PD, Hanaoka M. The circadian regulation of photosynthesis. PHOTOSYNTHESIS RESEARCH 2014; 119:181-90. [PMID: 23529849 DOI: 10.1007/s11120-013-9811-8] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2012] [Accepted: 03/08/2013] [Indexed: 05/25/2023]
Abstract
Correct circadian regulation increases plant productivity, and photosynthesis is circadian-regulated. Here, we discuss the regulatory basis for the circadian control of photosynthesis. We discuss candidate mechanisms underpinning circadian oscillations of light harvesting and consider how the circadian clock modulates CO2 fixation by Rubisco. We show that new techniques may provide a platform to better understand the signalling pathways that couple the circadian clock with the photosynthetic apparatus. Finally, we discuss how understanding circadian regulation in model systems is underpinning research into the impact of circadian regulation in crop species.
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Affiliation(s)
- Antony N Dodd
- School of Biological Sciences, University of Bristol, Bristol, BS8 1UG, UK,
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8
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Woodson JD, Perez-Ruiz JM, Schmitz RJ, Ecker JR, Chory J. Sigma factor-mediated plastid retrograde signals control nuclear gene expression. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2013; 73:1-13. [PMID: 22950756 PMCID: PMC3605210 DOI: 10.1111/tpj.12011] [Citation(s) in RCA: 118] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2012] [Revised: 08/29/2012] [Accepted: 09/03/2012] [Indexed: 05/20/2023]
Abstract
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 tRNA(Glu) . 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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Affiliation(s)
- Jesse D. Woodson
- Plant Biology Laboratory, The Salk Institute, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Juan M. Perez-Ruiz
- Plant Biology Laboratory, The Salk Institute, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA
- Howard Hughes Medical Institute, The Salk Institute, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Robert J. Schmitz
- Plant Biology Laboratory, The Salk Institute, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA
- Howard Hughes Medical Institute, The Salk Institute, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA
- Genomic Analysis Laboratory, The Salk Institute, 10010 North Torrey Pines Road, La Jolla, CA, 92037, USA
| | - Joseph R. Ecker
- Plant Biology Laboratory, The Salk Institute, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA
- Howard Hughes Medical Institute, The Salk Institute, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA
- Genomic Analysis Laboratory, The Salk Institute, 10010 North Torrey Pines Road, La Jolla, CA, 92037, USA
| | - Joanne Chory
- Plant Biology Laboratory, The Salk Institute, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA
- Howard Hughes Medical Institute, The Salk Institute, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA
- For correspondence ()
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9
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Woodson JD, Perez-Ruiz JM, Schmitz RJ, Ecker JR, Chory J. Sigma factor-mediated plastid retrograde signals control nuclear gene expression. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2013; 73:1-13. [PMID: 22950756 DOI: 10.1111/tpj.12011 [epub ahead of print]] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2012] [Revised: 08/29/2012] [Accepted: 09/03/2012] [Indexed: 05/28/2023]
Abstract
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 tRNA(Glu) . 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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Affiliation(s)
- Jesse D Woodson
- Plant Biology Laboratory, The Salk Institute, 10010 North Torrey Pines Road, La Jolla, CA, 92037, USA
| | - Juan M Perez-Ruiz
- Plant Biology Laboratory, The Salk Institute, 10010 North Torrey Pines Road, La Jolla, CA, 92037, USA
- Howard Hughes Medical Institute, The Salk Institute, 10010 North Torrey Pines Road, La Jolla, CA, 92037, USA
| | - Robert J Schmitz
- Plant Biology Laboratory, The Salk Institute, 10010 North Torrey Pines Road, La Jolla, CA, 92037, USA
- Howard Hughes Medical Institute, The Salk Institute, 10010 North Torrey Pines Road, La Jolla, CA, 92037, USA
- Genomic Analysis Laboratory, The Salk Institute, 10010 North Torrey Pines Road, La Jolla, CA, 92037, USA
| | - Joseph R Ecker
- Plant Biology Laboratory, The Salk Institute, 10010 North Torrey Pines Road, La Jolla, CA, 92037, USA
- Howard Hughes Medical Institute, The Salk Institute, 10010 North Torrey Pines Road, La Jolla, CA, 92037, USA
- Genomic Analysis Laboratory, The Salk Institute, 10010 North Torrey Pines Road, La Jolla, CA, 92037, USA
| | - Joanne Chory
- Plant Biology Laboratory, The Salk Institute, 10010 North Torrey Pines Road, La Jolla, CA, 92037, USA
- Howard Hughes Medical Institute, The Salk Institute, 10010 North Torrey Pines Road, La Jolla, CA, 92037, USA
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10
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Light Stress Proteins in Viruses, Cyanobacteria and Photosynthetic Eukaryota. PHOTOSYNTHESIS 2012. [DOI: 10.1007/978-94-007-1579-0_14] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/10/2023]
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Solymosi K, Schoefs B. Etioplast and etio-chloroplast formation under natural conditions: the dark side of chlorophyll biosynthesis in angiosperms. PHOTOSYNTHESIS RESEARCH 2010; 105:143-66. [PMID: 20582474 DOI: 10.1007/s11120-010-9568-2] [Citation(s) in RCA: 95] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2009] [Accepted: 05/30/2010] [Indexed: 05/03/2023]
Abstract
Chloroplast development is usually regarded as proceeding from proplastids. However, direct or indirect conversion pathways have been described in the literature, the latter involving the etioplast or the etio-chloroplast stages. Etioplasts are characterized by the absence of chlorophylls (Chl-s) and the presence of a unique inner membrane network, the prolamellar body (PLB), whereas etio-chloroplasts contain Chl-s and small PLBs interconnected with chloroplast thylakoids. As etioplast development requires growth in darkness for several days, this stage is generally regarded as a nonnatural pathway of chloroplast development occurring only under laboratory conditions. In this article, we have reviewed the data in favor of the involvement of etioplasts and etio-chloroplasts as intermediary stage(s) in chloroplast formation under natural conditions, the molecular aspects of PLB formation and we propose a dynamic model for its regulation.
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Affiliation(s)
- Katalin Solymosi
- Department of Plant Anatomy, Institute of Biology, Eötvös University, Pázmány P. s. 1/C, 1117 Budapest, Hungary.
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12
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Richter A, Peter E, Pörs Y, Lorenzen S, Grimm B, Czarnecki O. Rapid dark repression of 5-aminolevulinic acid synthesis in green barley leaves. PLANT & CELL PHYSIOLOGY 2010; 51:670-81. [PMID: 20375109 DOI: 10.1093/pcp/pcq047] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
In photosynthetic organisms chlorophyll and heme biosynthesis is tightly regulated at various levels in response to environmental adaptation and plant development. The formation of 5-aminolevulinic acid (ALA) is the key regulatory step and provides adequate amounts of the common precursor molecule for the Mg and Fe branches of tetrapyrrole biosynthesis. Pathway control prevents accumulation of metabolic intermediates and avoids photo-oxidative damage. In angiosperms reduction of protochlorophyllide (Pchlide) to chlorophyllide is catalyzed by the light-dependent NADPH:Pchlide oxidoreductase (POR). Although a correlation between down-regulated ALA synthesis and accumulation of Pchlide in the dark was proposed a long time ago, the time-resolved mutual dependency has never been analyzed. Taking advantage of the high metabolic activity of young barley (Hordeum vulgare L.) seedlings, in planta ALA synthesis could be determined with high time-resolution. ALA formation declined immediately after transition from light to dark and correlated with an immediate accumulation of POR-bound Pchlide within the first 60 min in darkness. The flu homologous barley mutant tigrina d(12) uncouples ALA synthesis from dark-suppression and continued to form ALA in darkness without a significant change in synthesis rate in this time interval. Similarly, inhibition of protoporphyrinogen IX oxidase by acifluorfen resulted in a delayed accumulation of Pchlide during the entire dark period and a weak repression of ALA synthesis in darkness. Moreover, it is demonstrated that dark repression of ALA formation relies rather on rapid post-translational regulation in response to accumulating Pchlide than on changes in nuclear gene expression.
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Affiliation(s)
- Andreas Richter
- Humboldt University Berlin, Institute of Biology, Department of Plant Physiology, Unter den Linden 6, D-10099 Berlin, Germany
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13
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Masuda T, Fujita Y. Regulation and evolution of chlorophyll metabolism. Photochem Photobiol Sci 2008; 7:1131-49. [PMID: 18846277 DOI: 10.1039/b807210h] [Citation(s) in RCA: 146] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Chlorophylls are the most abundant tetrapyrrole molecules essential for photosynthesis in photosynthetic organisms. After many years of intensive research, most of the genes encoding the enzymes for the pathway have been identified, and recently the underlying molecular mechanisms have been elucidated. These studies revealed that the regulation of chlorophyll metabolism includes all levels of control to allow a balanced metabolic flow in response to external and endogenous factors and to ensure adaptation to varying needs of chlorophyll during plant development. Furthermore, identification of biosynthetic genes from various organisms and genetic analysis of functions of identified genes enables us to predict the evolutionary scenario of chlorophyll metabolism. In this review, based on recent findings, we discuss the regulation and evolution of chlorophyll metabolism.
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Affiliation(s)
- Tatsuru Masuda
- Department of General Systems Studies, Graduate School of Arts and Sciences, The University of Tokyo, Komaba 3-8-1, Tokyo, 153-8902, Japan.
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14
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Martin-Tryon EL, Harmer SL. XAP5 CIRCADIAN TIMEKEEPER coordinates light signals for proper timing of photomorphogenesis and the circadian clock in Arabidopsis. THE PLANT CELL 2008; 20:1244-59. [PMID: 18515502 PMCID: PMC2438460 DOI: 10.1105/tpc.107.056655] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2007] [Revised: 04/24/2008] [Accepted: 05/08/2008] [Indexed: 05/24/2023]
Abstract
Numerous, varied, and widespread taxa have an internal circadian clock that allows anticipation of rhythmic changes in the environment. We have identified XAP5 CIRCADIAN TIMEKEEPER (XCT), an Arabidopsis thaliana gene important for light regulation of the circadian clock and photomorphogenesis. XCT is essential for proper clock function: xct mutants display a shortened circadian period in all conditions tested. Interestingly, XCT plays opposite roles in plant responses to light depending both on trait and wavelength. The clock in xct plants is hypersensitive to red but shows normal responses to blue light. By contrast, inhibition of hypocotyl elongation in xct is hyposensitive to red light but hypersensitive to blue light. Finally, XCT is important for ribulose-1,5-bisphosphate carboxylase/oxygenase production and plant greening in response to light. This novel combination of phenotypes suggests XCT may play a global role in coordinating growth in response to the light environment. XCT contains a XAP5 domain and is well conserved across diverse taxa, suggesting it has a common function in higher eukaryotes. Downregulation of the XCT ortholog in Caenorhabditis elegans is lethal, suggesting that studies in Arabidopsis may be instrumental to understanding the biochemical activity of XCT.
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Affiliation(s)
- Ellen L Martin-Tryon
- Section of Plant Biology, College of Biological Sciences, University of California, Davis, California 95616, USA
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15
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Abstract
Cyanobacteria such as Synechococcus elongatus PCC 7942, Thermosynechococcus elongatus BP-1, and Synechocystis species strain PCC 6803 have an endogenous timing mechanism that can generate and maintain a 24 h (circadian) periodicity to global (whole genome) gene expression patterns. This rhythmicity extends to many other physiological functions, including chromosome compaction. These rhythmic patterns seem to reflect the periodicity of availability of the primary energy source for these photoautotrophic organisms, the Sun. Presumably, eons of environmentally derived rhythmicity--light/dark cycles--have simply been mechanistically incorporated into the regulatory networks of these cyanobacteria. Genetic and biochemical experimentation over the last 15 years has identified many key components of the primary timing mechanism that generates rhythmicity, the input pathways that synchronize endogenous rhythms to exogenous rhythms, and the output pathways that transduce temporal information from the timekeeper to the regulators of gene expression and function. Amazingly, the primary timing mechanism has evidently been extracted from S. elongatus PCC 7942 and can also keep time in vitro. Mixing the circadian clock proteins KaiA, KaiB, and KaiC from S. elongatus PCC 7942 in vitro and adding ATP results in a circadian rhythm in the KaiC protein phosphorylation state. Nonetheless, many questions still loom regarding how this circadian clock mechanism works, how it communicates with the environment and how it regulates temporal patterns of gene expression. Many details regarding structure and function of the individual clock-related proteins are provided here as a basis to discuss these questions. A strong, data-intensive foundation has been developed to support the working model for the cyanobacterial circadian regulatory system. The eventual addition to that model of the metabolic parameters participating in the command and control of this circadian global regulatory system will ultimately allow a fascinating look into whole-cell physiology and metabolism and the consequential organization of global gene expression patterns.
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Affiliation(s)
- Stanly B Williams
- Department of Biology, Life Science Building, University of Utah, Salt Lake City, UT 84112, USA
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Alawady A, Reski R, Yaronskaya E, Grimm B. Cloning and expression of the tobacco CHLM sequence encoding Mg protoporphyrin IX methyltransferase and its interaction with Mg chelatase. PLANT MOLECULAR BIOLOGY 2005; 57:679-91. [PMID: 15988563 DOI: 10.1007/s11103-005-1427-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2005] [Accepted: 01/29/2005] [Indexed: 05/03/2023]
Abstract
S-adenosyl-L-methionine:Mg-protoporphyrin IX methyltransferase (MgPMT) is an enzyme in the Mg branch of the tetrapyrrole biosynthetic pathway. The nucleotide sequence of tobacco (Nicotiana tabacum) CHLM was identified and the cDNA sequence was used to express the precursor, the mature and a truncated recombinant MgPMT for enzymatic activity tests and for the formation of polyclonal antibodies. Comparison of the mature and the truncated MgPMT revealed three critical amino acids at the N-terminus of MgPMT for the maintenance of enzyme activity. To assess the contribution of CHLM expression to the control of the metabolic flow in the tetrapyrrole pathway, CHLM transcripts and protein levels, the enzyme activity and the steady-state levels of Mg protoporphyrin and Mg protoporphyrin monomethylester were analysed during greening of seedlings and plant development as well as under day/night and continuous growth conditions. These expression studies revealed posttranslational activation of MgPMT during greening and light/dark-cycles. Using the yeast two-hybrid system physical interaction was demonstrated between MgPMT and the CHLH subunit of Mg chelatase. Activity of recombinant MgPMT expressed in yeast cells was stimulated in the presence of the recombinant CHLH subunit. Implications for posttranslational regulation of MgPMT are discussed for the enzymatic steps at the beginning of the Mg branch.
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Affiliation(s)
- Ali Alawady
- Institut für Biologie, Pflanzenphysiologie, Humboldt Universität, Philippstr.13, Haus 12, 10115 Berlin, Deutschland
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Alawady AE, Grimm B. Tobacco Mg protoporphyrin IX methyltransferase is involved in inverse activation of Mg porphyrin and protoheme synthesis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2005; 41:282-90. [PMID: 15634204 DOI: 10.1111/j.1365-313x.2004.02291.x] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Protoporphyrin, a metabolic intermediate of tetrapyrrole biosynthesis, is metabolized by Mg chelatase and ferrochelatase and is directed into the Mg-branch for chlorophyll synthesis and in the Fe-branch for protoheme synthesis respectively. Regulation of the enzyme activities at the beginning of this branchpoint ensures accurate partition of protoporphyrin, but is still not entirely understood. Transgenic tobacco plants were generated that express antisense or sense RNA for inhibited and excessive expression of Mg protoporphyrin methyltransferase (MgPMT) respectively. This enzyme accepts Mg protoporphyrin from Mg chelatase and catalyses the transfer of a methyl group to the carboxyl group of the C13-propionate side chain. Low MgPMT activity is correlated with reduced Mg chelatase activity and a low synthesis rate of 5-aminolevulinate, but with enhanced ferrochelatase activity. In contrast, high MgPMT activity leads to inverse activity profiles: high activities of Mg chelatase and for 5-aminolevulinate synthesis, but reduced activity of ferrochelatase, indicating a direct influence of MgPMT in combination with Mg chelatase on the metabolic flux of ALA and the distribution of protoporphyrin into the branched pathway. The modified enzyme activities in tetrapyrrole biosynthesis in the transgenic plants can be explained with changes of certain corresponding mRNA contents: increased 5-aminolevulinate synthesis and Mg chelatase activity correlate with enhanced transcript levels of the HemA, Gsa, and CHLH gene encoding glutamyl-tRNA reductase, glutamate-1-semialdehyde aminotransferase and a Mg chelatase subunit respectively. It is proposed that reduced and increased MgPMT activity in chloroplasts is communicated to the cytoplasm for modulating transcriptional activities of regulatory enzymes of the pathway.
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Affiliation(s)
- Ali E Alawady
- Institut für Biologie/Pflanzenphysiologie, Humboldt-Universität zu Berlin, Philippstr.13, Haus 12, 10115 Berlin, Germany
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Matsumoto F, Obayashi T, Sasaki-Sekimoto Y, Ohta H, Takamiya KI, Masuda T. Gene expression profiling of the tetrapyrrole metabolic pathway in Arabidopsis with a mini-array system. PLANT PHYSIOLOGY 2004; 135:2379-91. [PMID: 15326282 PMCID: PMC520805 DOI: 10.1104/pp.104.042408] [Citation(s) in RCA: 111] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2004] [Revised: 04/30/2004] [Accepted: 05/03/2004] [Indexed: 05/20/2023]
Abstract
Tetrapyrrole compounds, such as chlorophylls, hemes, and phycobilins, are synthesized in many enzymatic steps. For regulation of the tetrapyrrole metabolic pathway, it is generally considered that several specific isoforms catalyzing particular enzymatic steps control the flow of tetrapyrrole intermediates by differential regulation of gene expression depending on environmental and developmental factors. However, the coordination of such regulatory steps and orchestration of the overall tetrapyrrole metabolic pathway are still poorly understood. In this study, we developed an original mini-array system, which enables the expression profiling of each gene involved in tetrapyrrole biosynthesis simultaneously with high sensitivity. With this system, we performed a transcriptome analysis of Arabidopsis seedlings in terms of the onset of greening, endogenous rhythm, and developmental control. Data presented here clearly showed that based on their expression profiles at the onset of greening, genes involved in tetrapyrrole biosynthesis can be classified into four categories, in which genes are coordinately regulated to control the biosynthesis. Moreover, genes in the same group were similarly controlled in an endogenous rhythmic manner but also by a developmental program. The physiological significance of these gene clusters is discussed.
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Affiliation(s)
- Fuminori Matsumoto
- Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8501, Japan
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Abstract
Cyanobacteria such as Synechococcus elongatus PCC 7942 exhibit 24-h rhythms of gene expression that are controlled by an endogenous circadian clock that is mechanistically distinct from those described for diverse eukaryotes. Genetic and biochemical experiments over the past decade have identified key components of the circadian oscillator, input pathways that synchronize the clock with the daily environment, and output pathways that relay temporal information to downstream genes. The mechanism of the cyanobacterial circadian clock that is emerging is based principally on the assembly and disassembly of a large complex at whose heart are the proteins KaiA, KaiB, and KaiC. Signal transduction pathways that feed into and out of the clock employ protein domains that are similar to those in two-component regulatory systems of bacteria.
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Affiliation(s)
- J L Ditty
- Department of Biology, University of St. Thomas, St. Paul, Minnesota 55105, USA.
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20
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Woitsch S, Römer S. Expression of xanthophyll biosynthetic genes during light-dependent chloroplast differentiation. PLANT PHYSIOLOGY 2003; 132:1508-17. [PMID: 12857831 PMCID: PMC167089 DOI: 10.1104/pp.102.019364] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2002] [Revised: 02/04/2003] [Accepted: 02/23/2003] [Indexed: 05/20/2023]
Abstract
In higher plants, etioplast to chloroplast differentiation is characterized by dramatic ultrastructural changes of the plastid and a concomitant increase in chlorophylls and carotenoids. Whereas the formation and function of carotenes and their oxygenated derivatives, the xanthophylls, have been well studied, little is known about the regulation of the genes involved in xanthophyll biosynthesis. Here, we analyze the expression of three xanthophyll biosynthetic genes (i.e. beta-carotene hydroxylase [bhy], zeaxanthin epoxidase [zep], and violaxanthin de-epoxidase [vde]) during de-etiolation of seedlings of tobacco (Nicotiana tabacum L. cv Samsun) under different light conditions. White-light illumination caused an increase in the amount of all corresponding mRNAs. The expression profiles of bhy and zep not only resembled each other but were also similar to the pattern of a gene encoding a major light-harvesting protein of photosystem II. This finding indicates a coordinated synthesis during formation of the antenna complex. In contrast, the expression pattern of vde was clearly different. Furthermore, the gene expression of bhy was shown to be modulated after illumination with different white-light intensities. The expression of all xanthophyll biosynthetic genes under examination was up-regulated upon exposure to red, blue, and white light. Gene expression of bhy and vde but not of zep was more pronounced under red-light illumination, pointing at an involvement of the phytochrome system. Expression analysis in the presence of the photosynthetic electron transport inhibitors 3-(3,4-dichlorophenyl)-1,1-dimethyl-urea and 2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone indicated a redox control of transcription of two of the xanthophyll biosynthetic genes (bhy and zep).
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Affiliation(s)
- Sonja Woitsch
- Fachbereich Biologie, Lehrstuhl für Physiologie und Biochemie der Pflanzen, Universität Konstanz, Universitätsstrasse 10, 78434 Konstanz, Germany
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22
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Lee J, Herrin DL. Assessing the relative importance of light and the circadian clock in controlling chloroplast translation in Chlamydomonas reinhardtii. PHOTOSYNTHESIS RESEARCH 2002; 72:295-306. [PMID: 16228528 DOI: 10.1023/a:1019881306640] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Previous work has shown that transcription of a number of chloroplast-encoded genes, including those for photosynthesis, are under circadian clock control in Chlamydomonas reinhardtii. However, some of these genes encode long-lived mRNAs that are also subject to translational control. Rates of synthesis of the major chloroplast translation products vary dramatically (10-20-fold) during light-dark (LD) cycles, peaking in the light period. To determine whether this pattern reflects circadian clock control, LD-grown cells were shifted to continuous light (LL) and chloroplast protein synthesis monitored by periodic pulse-labeling in the presence of cycloheximide; chloroplast protein synthesis in LD was also examined for comparison. The LD patterns of synthesis of the major polypeptides (including D1, D2, and the large subunit of ribulose-1,5-bisphosphate carboxylase (LS)) were similar to those obtained previously in the absence of cycloheximide. In the LL condition, rates of synthesis of the major chloroplast translation products were high throughout the period examined ( approximately 36 h), fluctuating > 3-fold, although they were generally higher in the subjective light period. LD-grown cells were also shifted to continuous dark (DD) and chloroplast protein synthesis analyzed for approximately 24 h starting from the mid-dark period. There was a gradual decline in synthesis of the major proteins during the first subjective light period, which was followed by a very small peak in synthesis around the second subjective dark --> light transition. RNA blot analysis showed that the mRNAs for D1, D2 and LS were present at high levels during the period of declining translation. These results indicate that with photoautotrophic growth in LD cycles, the illumination conditions per se are more important than the clock in determining chloroplast translation, but the clock may contribute to this regulation. The advantages of controlling translation by a direct light response and transcription primarily by the circadian clock are discussed. Finally, evidence of translational control of elongation factor Tu synthesis was obtained.
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Affiliation(s)
- Jaesung Lee
- Molecular Cell and Developmental Biology Section and Institute for Cellular and Molecular Biology, School of Biological Sciences, University of Texas at Austin, Austin, TX, 78712, USA,
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23
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Adamska I. The Elip Family of Stress Proteins in the Thylakoid Membranes of Pro- and Eukaryota. REGULATION OF PHOTOSYNTHESIS 2001. [DOI: 10.1007/0-306-48148-0_28] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
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Kumar MA, Chaturvedi S, Söll D. Selective inhibition of HEMA gene expression by photooxidation in Arabidopsis thaliana. PHYTOCHEMISTRY 1999; 51:847-51. [PMID: 10423858 DOI: 10.1016/s0031-9422(99)00114-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Norflurazon (NF), a photobleaching herbicide, inhibits carotenoid biosynthesis. Lack of carotenoid pigments leads to photooxidative damage of chloroplasts. In this study of Arabidopsis thaliana we demonstrate that NF-treated photobleached plants are still able to make 5-aminolevulinic acid (ALA) the first precursor of porphyrins and tetrapyrroles. ALA is formed in the tRNA-dependent two-step C5-pathway in the chloroplast of plants. The expression of glutamyl-tRNA reductase (GluTR), the first enzyme in the pathway, was severely inhibited by NF, while treatment with this compound did not significantly reduce the levels of the other enzyme, glutamate-l-semialdehyde aminomutase, or of tRNA(Glu), the initial metabolite of the pathway. Extracts of these plants retained the capacity, albeit reduced, to convert exogenously added glutamate to ALA. Thus, the much-reduced level of ALA formation in photobleached plants is due to selective inhibition of GluTR expression.
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Affiliation(s)
- M A Kumar
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06520-8114, USA
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25
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Abstract
Photosynthesis is one of the important processes that enable life on earth. To optimize photosynthesis reactions during a solar day, most of them are timed to be active during the light phase. This includes the components of the thylakoid membranes in chloroplasts. Prominent representatives are the proteins of the light-harvesting complex (LHC). The synthesis of both the Lhc mRNA and the LHC protein occurs during the day and is regulated by the circadian clock, exhibiting the following pattern: increasing levels after sunrise, reaching a maximum around noon, and decreasing levels in the afternoon. To elucidate the involved control elements and regulatory circuits, the following strategies were applied: (1) analysis of promoters of Lhc genes, (2) analysis of DNA binding proteins, and (3) screening and investigation of mutants. The most promising elements found so far that may be involved in mediating the circadian rhythmicity of Lhc mRNA oscillations are a myb-like transcription factor CCA1 (Wang et al. 1997) and the corresponding DNA binding sequence (Piechulla et al. 1998).
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Affiliation(s)
- B Piechulla
- University of Rostock, Department of Molecular Physiology of Plants and Microorganisms, Rostock, Germany
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26
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Sangwan I, O'Brian MR. Expression of a soybean gene encoding the tetrapyrrole-synthesis enzyme glutamyl-tRNA reductase in symbiotic root nodules. PLANT PHYSIOLOGY 1999; 119:593-8. [PMID: 9952455 PMCID: PMC32136 DOI: 10.1104/pp.119.2.593] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/1998] [Accepted: 10/23/1998] [Indexed: 05/22/2023]
Abstract
Heme and chlorophyll accumulate to high levels in legume root nodules and in photosynthetic tissues, respectively, and they are both derived from the universal tetrapyrrole precursor delta-aminolevulinic acid (ALA). The first committed step in ALA and tetrapyrrole synthesis is catalyzed by glutamyl-tRNA reductase (GTR) in plants. A soybean (Glycine max) root-nodule cDNA encoding GTR was isolated by complementation of an Escherichia coli GTR-defective mutant for restoration of ALA prototrophy. Gtr mRNA was very low in uninfected roots but accumulated to high levels in root nodules. The induction of Gtr mRNA in developing nodules was subsequent to that of the gene Enod2 (early nodule) and coincided with leghemoglobin mRNA accumulation. Genomic analysis revealed two Gtr genes, Gtr1 and a 3' portion of Gtr2, which were isolated from the soybean genome. RNase-protection analysis using probes specific to Gtr1 and Gtr2 showed that both genes were expressed, but Gtr1 mRNA accumulated to significantly higher levels. In addition, the qualitative patterns of expression of Gtr1 and Gtr2 were similar to each other and to total Gtr mRNA in leaves and nodules of mature plants and etiolated plantlets. The data indicate that Gtr1 is universal for tetrapyrrole synthesis and that a Gtr gene specific for a tissue or tetrapyrrole is unlikely. We suggest that ALA synthesis in specialized root nodules involves an altered spatial expression of genes that are otherwise induced strongly only in photosynthetic tissues of uninfected plants.
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Affiliation(s)
- I Sangwan
- Department of Biochemistry, State University of New York, Buffalo, New York 14214, USA
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27
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Zhong HH, Painter JE, Salomé PA, Straume M, McClung CR. Imbibition, but not release from stratification, sets the circadian clock in Arabidopsis seedlings. THE PLANT CELL 1998; 10:2005-17. [PMID: 9836741 PMCID: PMC143968 DOI: 10.1105/tpc.10.12.2005] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Circadian rhythms in the abundance of the CAT2 catalase mRNA were not seen in etiolated seedlings but developed upon illumination. These circadian oscillations were preceded by a rapid and transient induction of CAT2 mRNA abundance that varied strikingly according to the timing (circadian phase) of the onset of illumination. This variation oscillated with a circadian periodicity of approximately 28 hr, indicating that the circadian oscillator is running in etiolated seedlings and regulates (gates) the induction of CAT2 by light. Moreover, because we assayed populations of seedlings, we infer that the individual clocks among populations of etiolated seedlings were synchronized before the onset of illumination. What developmental or environmental signals synchronized the clocks among seedlings? Varying the phase of the onset of illumination relative to release from stratification failed to affect the acute induction of CAT2, indicating that the temperature step from 4 to 22 degrees C associated with release from stratification did not reset the circadian clock. However, the acute induction of CAT2 mRNA varied with time after imbibition, demonstrating that imbibition provides a signal capable of resetting the circadian clock and of synchronizing the clocks among populations of seedlings.
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Affiliation(s)
- H H Zhong
- Department of Biological Sciences, Dartmouth College, Hanover, New Hampshire 03755, USA
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28
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Montane MH, Tardy F, Kloppstech K, Havaux M. Differential control of xanthophylls and light-induced stress proteins, as opposed to light-harvesting chlorophyll a/b proteins, during photosynthetic acclimation of barley leaves to light irradiance. PLANT PHYSIOLOGY 1998; 118:227-35. [PMID: 9733542 PMCID: PMC34860 DOI: 10.1104/pp.118.1.227] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/1998] [Accepted: 05/29/1998] [Indexed: 05/19/2023]
Abstract
Barley (Hordeum vulgare L.) plants were grown at different photon flux densities ranging from 100 to 1800 &mgr;mol m-2 s-1 in air and/or in atmospheres with reduced levels of O2 and CO2. Low O2 and CO2 partial pressures allowed plants to grow under high photosystem II (PSII) excitation pressure, estimated in vivo by chlorophyll fluorescence measurements, at moderate photon flux densities. The xanthophyll-cycle pigments, the early light-inducible proteins, and their mRNA accumulated with increasing PSII excitation pressure irrespective of the way high excitation pressure was obtained (high-light irradiance or decreased CO2 and O2 availability). These findings indicate that the reduction state of electron transport chain components could be involved in light sensing for the regulation of nuclear-encoded chloroplast gene expression. In contrast, no correlation was found between the reduction state of PSII and various indicators of the PSII light-harvesting system, such as the chlorophyll a-to-b ratio, the abundance of the major pigment-protein complex of PSII (LHCII), the mRNA level of LHCII, the light-saturation curve of O2 evolution, and the induced chlorophyll-fluorescence rise. We conclude that the chlorophyll antenna size of PSII is not governed by the redox state of PSII in higher plants and, consequently, regulation of early light-inducible protein synthesis is different from that of LHCII.
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Affiliation(s)
- MH Montane
- Commissariat a l'Energie Atomique/Cadarache, Departement d'Ecophysiologie Vegetale et de Microbiologie, Laboratoire de Radiobiologie Vegetale (M.-H.M.)
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Kreps JA, Kay SA. Coordination of Plant Metabolism and Development by the Circadian Clock. THE PLANT CELL 1997; 9:1235-1244. [PMID: 12237384 PMCID: PMC156994 DOI: 10.1105/tpc.9.7.1235] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Affiliation(s)
- J. A. Kreps
- Department of Cell Biology, Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037
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30
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Argyroudi-Akoyunoglou JH, Prombona A. Light-independent endogenous circadian rhythm in the capacity for chlorophyll formation. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 1996. [DOI: 10.1016/s1011-1344(96)07380-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Abstract
The significance of the circadian clock for living organisms is not fully understood. Recent findings demonstrate circadian control of transcription of quite a number of genes with individual maxima throughout the entire day. Evidence in favor of circadian-clock-controlled translation has also been documented. In this article, we want to promote the idea that in plants the clock functions as a regulator which coordinates critical cellular processes, such as cell division, nitrate reduction, or synthesis of chlorophyll-protein complexes, in such a way that the generation of dangerous, oxidative radicals or exposure to harmful light is minimized. This has been achieved by plant organisms either by confining gene expression to the dark phase or by a tight coordination of different tiers of gene expression during the light phase. This leads to the consequence for the researcher that the time of experimentation needs to be carefully considered and documented. It also follows that one might lose important findings if only a particular portion of the day is investigated.
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Affiliation(s)
- J Beator
- Institut für Botanik, Universität Hannover, Germany
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32
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O'Brian MR. Heme synthesis in the rhizobium-legume symbiosis: a palette for bacterial and eukaryotic pigments. J Bacteriol 1996; 178:2471-8. [PMID: 8626311 PMCID: PMC177968 DOI: 10.1128/jb.178.9.2471-2478.1996] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Affiliation(s)
- M R O'Brian
- Department of Biochemistry, State University of New York at Buffalo 14214, USA
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33
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Hwang S, Kawazoe R, Herrin DL. Transcription of tufA and other chloroplast-encoded genes is controlled by a circadian clock in Chlamydomonas. Proc Natl Acad Sci U S A 1996; 93:996-1000. [PMID: 8577775 PMCID: PMC40018 DOI: 10.1073/pnas.93.3.996] [Citation(s) in RCA: 82] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Levels of mRNA for the chloroplast-encoded elongation factor Tu (tufA) showed a dramatic daily oscillation in the green alga Chlamydomonas reinhardtii, peaking once each day in the early light period. The oscillation of tufA mRNA levels continued in cells shifted to continuous light or continuous dark for at least 2-3 days. Run-off transcription analyses showed that the rate of tufA transcription also peaked early in the light period and, moreover, that this transcriptional oscillation continued in cells shifted to continuous conditions. The half-life of tufA mRNA was estimated at different times and found to vary considerably during a light-dark cycle but not in cells shifted to continuous light. Light-dark patterns of transcription of several other chloroplast-encoded genes were examined and also found to persist in cells shifted to continuous light or dark. These results indicate that a circadian clock controls the transcription of tufA and other chloroplast-encoded genes.
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Affiliation(s)
- S Hwang
- Botany Department, University of Texas at Austin 78713-7640, USA
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34
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Winter L, Stöcker S, Merforth N, Mühlbach HP, Piechulla B. Circadian oscillations of Lhc mRNAs in a photoautotrophic cell culture of Lycopersicon peruvianum. PHOTOSYNTHESIS RESEARCH 1996; 47:77-84. [PMID: 24301709 DOI: 10.1007/bf00017755] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/1995] [Accepted: 11/06/1995] [Indexed: 06/02/2023]
Abstract
Fourteen genes encoding proteins of the light harvesting complex (Lhc) are expressed in a photoautotrophic cell culture from the wild species of tomato (Lycopersicon peruvianum). For two genes, Lhca2 (cab7) and Lhcb2(*)1 (cab4), a rhythmic oscillation of the transcript accumulation is observed under light/dark and constant dark conditions indicating that gene expression is controlled by a circadian clock in the tomato cell culture. The circadian expression of the Lhc genes remains present after application of 2,2'-dipyridyl. However, the amplitude of Lhc mRNA oscillations and the photosynthetic capacity (Fmax/Fo) decrease significantly. The transcript accumulations of psbA, rbcS and rbcL are less or not at all affected by 2,2'-dipyridyl.
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Affiliation(s)
- L Winter
- Institut für Biochemie der Pflanze, Untere Karspüle 2, 37073, Göttingen, Germany
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35
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Matters GL, Beale SI. Blue-Light-Regulated Expression of Genes for Two Early Steps of Chlorophyll Biosynthesis in Chlamydomonas reinhardtii. PLANT PHYSIOLOGY 1995; 109:471-479. [PMID: 12228605 PMCID: PMC157609 DOI: 10.1104/pp.109.2.471] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
In light:dark-synchronized cultures of Chlamydomonas reinhardtii, the genes encoding the enzymes for two early steps of chlorophyll biosynthesis, glutamate-1-semialdehyde aminotransferase (gsa) and [delta]-aminolevulinic acid dehydratase (alad), are expressed at high levels early in the light phase, just prior to a rapid burst of chlorophyll synthesis. Induction of gsa mRNA in synchronized cells is totally dependent on light, whereas induction of alad mRNA occurs to approximately one-half the light-induced level even in cells kept in the dark during the light phase and appears to be dependent on the cell cycle or a circadian rhythm. gsa mRNA and alad mRNA accumulation is induced by light that was passed through blue (400-480 nm) or green (490-590 nm) filters but not by light that was passed through orange (>560 nm) or red (>610 nm) filters, indicating the participation of a blue-light photoreceptor system rather than a protochlorophyllide- or rhodopsin-based photoreceptor. Light induction of gsa mRNA accumulation is absent in a carotenoid-deficient mutant, which suggests that a carotenoid-containing blue-light photoreceptor is involved. In contrast, pretreatment of wild-type cells with either of two flavin antagonists, phenylacetic acid and KI, does not prevent the light induction. In the later part of the light phase, the gsa mRNA level decreases more rapidly than that of alad mRNA. Turnover studies indicate that the half-life of alad mRNA is twice that of gsa mRNA. This difference in mRNA stability partially accounts for the more rapid decline in gsa mRNA levels after the peak of light induction is reached. Thus, differential blue-light induction and stability of mRNAs regulates the expression of these two chlorophyll biosynthetic genes.
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Affiliation(s)
- G. L. Matters
- Division of Biology and Medicine, Brown University, Providence, Rhode Island 02912
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Armstrong GA, Runge S, Frick G, Sperling U, Apel K. Identification of NADPH:protochlorophyllide oxidoreductases A and B: a branched pathway for light-dependent chlorophyll biosynthesis in Arabidopsis thaliana. PLANT PHYSIOLOGY 1995; 108:1505-17. [PMID: 7659751 PMCID: PMC157530 DOI: 10.1104/pp.108.4.1505] [Citation(s) in RCA: 186] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Illumination releases the arrest in chlorophyll (Chl) biosynthesis in etiolated angiosperm seedlings through the enzymatic photoreduction of protochlorophyllide (Pchlide) to chlorophyllide (Chlide), the first light-dependent step in chloroplast biogenesis. NADPH: Pchlide oxidoreductase (POR, EC 1.3.1.33), a nuclear-encoded plastid-localized enzyme, mediates this unique photoreduction. Paradoxically, light also triggers a drastic decrease in the amounts of POR activity and protein before the Chl accumulation rate reaches its maximum during greening. While investigating this seeming contradiction, we identified two distinct Arabidopsis thaliana genes encoding POR, in contrast to previous reports of only one gene in angiosperms. The genes, designated PorA and PorB, by analogy to the principal members of the phytochrome photoreceptor gene family, display dramatically different patterns of light and developmental regulation. PorA mRNA disappears within the first 4 h of greening, whereas PorB mRNA persists even after 16 h of illumination, mirroring the behavior of two distinct POR protein species. Experiments designed to help define the functions of POR A and POR B demonstrate exclusive expression of PorA in young seedlings and of PorB both in seedlings and in adult plants. Accordingly, we propose the existence of a branched light-dependent Chl biosynthesis pathway in which POR A performs a specialized function restricted to the initial stages of greening and POR B maintains Chl levels throughout angiosperm development.
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Affiliation(s)
- G A Armstrong
- Department of Plant Genetics, Swiss Federal Institute of Technology (ETH), Zürich
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Bei-Paraskevopoulou T, Anastassiou R, Argyroudi-Akoyunoglou J. Circadian expression of the light-harvesting protein of Photosystem II in etiolated bean leaves following a single red light pulse: Coordination with the capacity of the plant to form chlorophyll and the thylakoid-bound protease. PHOTOSYNTHESIS RESEARCH 1995; 44:93-106. [PMID: 24307029 DOI: 10.1007/bf00018300] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/1994] [Accepted: 12/21/1994] [Indexed: 06/02/2023]
Abstract
The appearance of the light harvesting II (LHC II) protein in etiolated bean leaves, as monitored by immunodetection in LDS-solubilized leaf protein extracts, is under phytochrome control. A single red light pulse induces accumulation of the protein, in leaves kept in the dark thereafter, which follows circadian oscillations similar to those earlier found for Lhcb mRNA (Tavladoraki et al. (1989) Plant Physiol 90: 665-672). These oscillations are closely followed by oscillations in the capacity of the leaf to form Chlorophyll (Chl) in the light, suggesting that the synthesis of the LHC II protein and its chromophore are in close coordination. Experiments with levulinic acid showed that PChl(ide) resynthesis does not affect the LHC II level nor its oscillations, but new Chl a synthesis affects LHC II stabilization in thylakoids, implicating a proteolytic mechanism. A proteolytic activity against exogenously added LHC II was detected in thylakoids of etiolated bean leaves, which was enhanced by the light pulse. The activity, also under phytochrome control, was found to follow circadian oscillations in verse to those in the stabilization of LHC II protein in thylakoids. Such a proteolytic mechanism therefore, may account for the circadian changes observed in LHC II protein level, being implicated in pigment-protein complex assembly/stabilization during thylakoid biogenesis.
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Frustaci JM, Sangwan I, O'Brian MR. gsa1 is a universal tetrapyrrole synthesis gene in soybean and is regulated by a GAGA element. J Biol Chem 1995; 270:7387-93. [PMID: 7706283 DOI: 10.1074/jbc.270.13.7387] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Expression of plant tetrapyrroles is high in photosynthetic tissues and in legume root nodules in the form of chlorophyll and heme, respectively. The universal tetrapyrrole precursor delta-aminolevulinic acid (ALA) is synthesized from glutamate 1-semialdehyde (GSA) by GSA aminotransferase in plants, which is encoded by gsa. Immunoblot analysis showed that GSA aminotransferase was expressed in soybean leaves and nodules, but not in roots, and that protein correlated with enzyme activity. These observations indicate that GSA aminotransferase expression is controlled in tetrapyrrole formation and argue against significant activity of an enzyme other than the well described aminotransferase for GSA-dependent ALA formation. gas mRNA and protein were induced in soybean nodules, and their activation was temporally intermediate between those of the respective early and late genes endo2 and lb. A GSA aminotransferase gene, designated gsa1, was isolated and appears to be one of two gsa genes in the soybean genome. gsa1 mRNA accumulated to high levels in leaves and nodules, but not in uninfected roots as discerned with a gsa1-specific probe. Message levels were higher in leaves from etiolated plantlets than in mature plants, and expression in the former was slightly elevated by light. The expression pattern of gsa1 mRNA was qualitatively similar to that of total gsa. The data strongly suggest that gsa1 is a universal tetrapyrrole synthesis gene and that a gsa gene specific for a tissue, tetrapyrrole, or light condition is unlikely. The gsa1 promoter contained a genetic element found in numerous Drosophila melanogaster genes; the so-called GAGA element displayed single-stranded character in vitro and formed a complex with nuclear factors from nodules and leaves but not from roots. From these observations we infer that the GAGA element is involved in the transcriptional control of gsa1.
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Affiliation(s)
- J M Frustaci
- Department of Biochemistry, State University of New York, Buffalo 14214, USA
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The greening process in cress seedlings IV. Light regulated expression of single Lhc genes. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B: BIOLOGY 1995. [DOI: 10.1016/1011-1344(94)07076-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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White RA, Hoober JK. Biogenesis of Thylakoid Membranes in Chlamydomonas reinhardtii y1 (A Kinetic Study of Initial Greening). PLANT PHYSIOLOGY 1994; 106:583-590. [PMID: 12232351 PMCID: PMC159564 DOI: 10.1104/pp.106.2.583] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Initiation of thylakoid membrane assembly was examined in degreened cells of Chlamydomonas reinhardtii y1 cells depleted of thylakoid membranes and photosynthetic activity by growth in the dark for 3 to 4 d. Photoreductive activities of photosystem II (PSII) and photosystem I (PSI) increased with no apparent lag when degreened cells were exposed to light at 38[deg]C. However, fluorescence transients induced by actinic light, which reflect the functional state of PSII, changed only slightly during the first 2 h of greening. When these cells were treated with 3-(3,4-dichlorophenyl)-1,1-dimethyl urea (DCMU) or saturating light, fluorescence increased commensurate with the cellular content of chlorophyll. In similar experiments with greening cells of C. reinhardtii CC-2341 (ac-u-g-2.3), a PSI-minus strain, fluorescence increased with chlorophyll without treatment with DCMU. These data suggested that fluorescence of initial PSII centers in greening y1 cells was quenched by activity of PSI. Continuous monitoring of fluorescence in the presence or absence of DCMU showed that assembly of quenched PSII centers occurred within seconds after exposure of y1 cells to light. These results are consistent with initial assembly of PSI and PSII within localized domains, where their proximity allows efficient energy coupling.
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Affiliation(s)
- R. A. White
- Department of Botany and Center for the Study of Early Events in Photosynthesis, Arizona State University, Tempe, Arizona 85287-1601
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