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Xu HF, Yu C, Bai Y, Zuo AW, Ye YT, Liu YR, Li ZK, Dai GZ, Chen M, Qiu BS. Red-light-dependent chlorophyll synthesis kindles photosynthetic recovery of chlorotic dormant cyanobacteria using a dark-operative enzyme. Curr Biol 2024:S0960-9822(24)01022-4. [PMID: 39146941 DOI: 10.1016/j.cub.2024.07.083] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2024] [Revised: 07/16/2024] [Accepted: 07/23/2024] [Indexed: 08/17/2024]
Abstract
Chlorosis dormancy resulting from nitrogen starvation and its resuscitation upon available nitrogen contributes greatly to the fitness of cyanobacterial population under nitrogen-fluctuating environments. The reinstallation of the photosynthetic machinery is a key process for resuscitation from a chlorotic dormant state; however, the underlying regulatory mechanism is still elusive. Here, we reported that red light is essential for re-greening chlorotic Synechocystis sp. PCC 6803 (a non-diazotrophic cyanobacterium) after nitrogen supplement under weak light conditions. The expression of dark-operative protochlorophyllide reductase (DPOR) governed by the transcriptional factor RpaB was strikingly induced by red light in chlorotic cells, and its deficient mutant lost the capability of resuscitation from a dormant state, indicating DPOR catalyzing chlorophyll synthesis is a key step in the photosynthetic recovery of dormant cyanobacteria. Although light-dependent protochlorophyllide reductase is widely considered as a master switch in photomorphogenesis, this study unravels the primitive DPOR as a spark to activate the photosynthetic recovery of chlorotic dormant cyanobacteria. These findings provide new insight into the biological significance of DPOR in cyanobacteria and even some plants thriving in extreme environments.
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Affiliation(s)
- Hai-Feng Xu
- School of Life Sciences and Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan 430079, Hubei, China
| | - Chen Yu
- School of Life Sciences and Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan 430079, Hubei, China
| | - Yang Bai
- School of Life Sciences and Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan 430079, Hubei, China
| | - Ai-Wei Zuo
- School of Life Sciences and Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan 430079, Hubei, China
| | - Ying-Tong Ye
- School of Life Sciences and Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan 430079, Hubei, China
| | - Yan-Ru Liu
- School of Life Sciences and Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan 430079, Hubei, China
| | - Zheng-Ke Li
- School of Life Sciences and Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan 430079, Hubei, China
| | - Guo-Zheng Dai
- School of Life Sciences and Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan 430079, Hubei, China.
| | - Min Chen
- School of Life and Environmental Sciences, University of Sydney, Sydney, NSW 2006, Australia
| | - Bao-Sheng Qiu
- School of Life Sciences and Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan 430079, Hubei, China.
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Vedalankar P, Tripathy BC. Light dependent protochlorophyllide oxidoreductase: a succinct look. PHYSIOLOGY AND MOLECULAR BIOLOGY OF PLANTS : AN INTERNATIONAL JOURNAL OF FUNCTIONAL PLANT BIOLOGY 2024; 30:719-731. [PMID: 38846463 PMCID: PMC11150229 DOI: 10.1007/s12298-024-01454-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2023] [Revised: 03/01/2024] [Accepted: 04/29/2024] [Indexed: 06/09/2024]
Abstract
Reducing protochlorophyllide (Pchlide) to chlorophyllide (Chlide) is a major regulatory step in the chlorophyll biosynthesis pathway. This reaction is catalyzed by light-dependent protochlorophyllide oxidoreductase (LPOR) in oxygenic phototrophs, particularly angiosperms. LPOR-NADPH and Pchlide form a ternary complex to be efficiently photo-transformed to synthesize Chlide and, subsequently, chlorophyll during the transition from skotomorphogenesis to photomorphogenesis. Besides lipids, carotenoids and poly-cis xanthophylls influence the formation of the photoactive LPOR complexes and the PLBs. The crystal structure of LPOR reveals evolutionarily conserved cysteine residues implicated in the Pchlide binding and catalysis around the active site. Different isoforms of LPOR viz PORA, PORB, and PORC expressed at different stages of chloroplast development play a photoprotective role by quickly transforming the photosensitive Pchlide to Chlide. Non-photo-transformed Pchlide acts as a photosensitizer to generate singlet oxygen that causes oxidative stress and cell death. Therefore, different isoforms of LPOR have evolved and differentially expressed during plant development to protect plants from photodamage and thus play a pivotal role during photomorphogenesis. This review brings out the salient features of LPOR structure, structure-function relationships, and ultra-fast photo transformation of Pchlide to Chlide by oligomeric and polymeric forms of LPOR.
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Affiliation(s)
| | - Baishnab C. Tripathy
- Department of Biotechnology, Sharda University, Greater Noida, Uttar Pradesh 201310 India
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Vedalankar P, Tripathy BC. Evolution of light-independent protochlorophyllide oxidoreductase. PROTOPLASMA 2019; 256:293-312. [PMID: 30291443 DOI: 10.1007/s00709-018-1317-y] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Accepted: 09/27/2018] [Indexed: 06/08/2023]
Abstract
The nonhomologous enzymes, the light-independent protochlorophyllide reductase (DPOR) and the light-dependent protochlorophyllide oxidoreductase (LPOR), catalyze the reduction of protochlorophyllide (Pchlide) to chlorophyllide (Chlide) in the penultimate step of biosynthesis of chlorophyll (Chl) required for photosynthetic light absorption and energy conversion. The two enzymes differ with respect to the requirement of light for catalysis and oxygen sensitivity. DPOR and LPOR initially evolved in the ancestral prokaryotic genome perhaps at different times. DPOR originated in the anoxygenic environment of the Earth from nitrogenase-like enzyme of methanogenic archaea. Due to the transition from anoxygenic to oxygenic photosynthesis in the prokaryote, the DPOR was mostly inactivated in the daytime by photosynthetic O2 leading to the evolution of oxygen-insensitive LPOR that could function in the light. The primary endosymbiotic event transferred the DPOR and LPOR genes to the eukaryotic phototroph; the DPOR remained in the genome of the ancestor that turned into the plastid, whereas LPOR was transferred to the host nuclear genome. From an evolutionary point of view, several compelling theories that explain the disappearance of DPOR from several species cutting across different phyla are as follows: (i) pressure of the oxygenic environment; (ii) change in the light conditions and temperature; and (iii) lineage-specific gene losses, RNA editing, and nonsynonymous substitution. Certain primary amino acid sequence and the physiochemical properties of the ChlL subunit of DPOR have similarity with that of LPOR suggesting a convergence of these two enzymes in certain evolutionary event. The newly obtained sequence data from different phototrophs will further enhance the width of the phylogenetic information on DPOR.
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Affiliation(s)
| | - Baishnab C Tripathy
- School of Life Sciences, Jawaharlal Nehru University, New Delhi, 110067, India.
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Kianianmomeni A. Cell-type specific light-mediated transcript regulation in the multicellular alga Volvox carteri. BMC Genomics 2014; 15:764. [PMID: 25194509 PMCID: PMC4167131 DOI: 10.1186/1471-2164-15-764] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2014] [Accepted: 09/03/2014] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND The multicellular green alga Volvox carteri makes use of none less than 13 photoreceptors, which are mostly expressed in a cell-type specific manner. This gives reason to believe that trasncriptome pattern of each cell type could change differentially in response to environmental light. Here, the cell-type specific changes of various transcripts from different pathways in response to blue, red and far-red light were analyzed. RESULTS In response to different light qualities, distinct changes in transcript accumulation of genes encoding proteins involved in chlorophyll and carotenoid biosynthesis, light-harvesting complexes, circadian clock and cell cycle control were observed. Namely, blue light tends to be effective to accumulate transcripts in the somatic cells; while red light leads to accumulate transcripts predominantly in the reproductive cells. Blue light also induced marked accumulation of two components of circadian rhythms only in the somatic cells, indicating that these clock-relevant components are affected by blue light in a cell-type specific manner. Further, we show that photosynthetic associated genes are regulated distinctly among cell types by different light qualities. CONCLUSION Our results suggest that Volvox uses different sophisticated cell-type specific light signaling pathways to modulate expression of genes involved in various cellular and metabolic pathways including circadian rhythms and photosynthesis in response to environmental light.
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Affiliation(s)
- Arash Kianianmomeni
- Department of Cellular and Developmental Biology of Plants, University of Bielefeld, Universitätsstr, 25, D-33615 Bielefeld, Germany.
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Kopečná J, Sobotka R, Komenda J. Inhibition of chlorophyll biosynthesis at the protochlorophyllide reduction step results in the parallel depletion of Photosystem I and Photosystem II in the cyanobacterium Synechocystis PCC 6803. PLANTA 2013; 237:497-508. [PMID: 23011568 DOI: 10.1007/s00425-012-1761-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2012] [Accepted: 09/03/2012] [Indexed: 05/07/2023]
Abstract
In most oxygenic phototrophs, including cyanobacteria, two independent enzymes catalyze the reduction of protochlorophyllide to chlorophyllide, which is the penultimate step in chlorophyll (Chl) biosynthesis. One is light-dependent NADPH:protochlorophyllide oxidoreductase (LPOR) and the second type is dark-operative protochlorophyllide oxidoreductase (DPOR). To clarify the roles of both enzymes, we assessed synthesis and accumulation of Chl-binding proteins in mutants of cyanobacterium Synechocystis PCC 6803 that either completely lack LPOR or possess low levels of the active enzyme due to its ectopic regulatable expression. The LPOR-less mutant grew photoautotrophically in moderate light and contained a maximum of 20 % of the wild-type (WT) Chl level. Both Photosystem II (PSII) and Photosystem I (PSI) were reduced to the same degree. Accumulation of PSII was mostly limited by the synthesis of antennae CP43 and especially CP47 as indicated by the accumulation of reaction center assembly complexes. The phenotype of the LPOR-less mutant was comparable to the strain lacking DPOR that also contained <25 % of the wild-type level of PSII and PSI when cultivated under light-activated heterotrophic growth conditions. However, in the latter case, we detected no reaction center assembly complexes, indicating that synthesis was almost completely inhibited for all Chl-proteins, including the D1 and D2 proteins.
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Affiliation(s)
- Jana Kopečná
- Department of Phototrophic Microorganisms, Institute of Microbiology, Academy of Sciences, Opatovický mlýn, Třeboň, Czech Republic
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Formighieri C, Ceol M, Bonente G, Rochaix JD, Bassi R. Retrograde signaling and photoprotection in a gun4 mutant of Chlamydomonas reinhardtii. MOLECULAR PLANT 2012; 5:1242-62. [PMID: 22767629 DOI: 10.1093/mp/sss051] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
GUN4 is a regulatory subunit of Mg-chelatase involved in the control of tetrapyrrole synthesis in plants and cyanobacteria. Here, we report the first characterization of a gun4 insertion mutant of the unicellular green alga Chlamydomonas reinhardtii. The mutant contains 50% of chlorophyll as compared to wild-type and accumulates ProtoIX. In contrast to the increase in LHC transcription, the accumulation of most LHC proteins is drastically diminished, implying posttranscriptional down-regulation in the absence of transcriptional coordination. We found that 803 genes change their expression level in gun4 as compared to wild-type, by RNA-Seq, and this wide-ranging effect on transcription is apparent under physiological conditions. Besides LHCs, we identified transcripts encoding enzymes of the tetrapyrrole pathway and factors involved in signal transduction, transcription, and chromatin remodeling. Moreover, we observe perturbations in electron transport with a strongly decreased PSI-to-PSII ratio. This is accompanied by an enhanced activity of the plastid terminal oxidase (PTOX) that could have a physiological role in decreasing photosystem II excitation pressure.
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Affiliation(s)
- Cinzia Formighieri
- Dipartimento di Biotecnologie, Università di Verona, Strada Le Grazie 15, I-37134 Verona, Italy
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Formighieri C, Ceol M, Bonente G, Rochaix JD, Bassi R. Retrograde signaling and photoprotection in a gun4 mutant of Chlamydomonas reinhardtii. MOLECULAR PLANT 2012. [PMID: 22767629 DOI: 10.1093/mp/sss051 [epub ahead of print]] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
GUN4 is a regulatory subunit of Mg-chelatase involved in the control of tetrapyrrole synthesis in plants and cyanobacteria. Here, we report the first characterization of a gun4 insertion mutant of the unicellular green alga Chlamydomonas reinhardtii. The mutant contains 50% of chlorophyll as compared to wild-type and accumulates ProtoIX. In contrast to the increase in LHC transcription, the accumulation of most LHC proteins is drastically diminished, implying posttranscriptional down-regulation in the absence of transcriptional coordination. We found that 803 genes change their expression level in gun4 as compared to wild-type, by RNA-Seq, and this wide-ranging effect on transcription is apparent under physiological conditions. Besides LHCs, we identified transcripts encoding enzymes of the tetrapyrrole pathway and factors involved in signal transduction, transcription, and chromatin remodeling. Moreover, we observe perturbations in electron transport with a strongly decreased PSI-to-PSII ratio. This is accompanied by an enhanced activity of the plastid terminal oxidase (PTOX) that could have a physiological role in decreasing photosystem II excitation pressure.
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Affiliation(s)
- Cinzia Formighieri
- Dipartimento di Biotecnologie, Università di Verona, Strada Le Grazie 15, I-37134 Verona, Italy
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Domingos RF, Simon DF, Hauser C, Wilkinson KJ. Bioaccumulation and effects of CdTe/CdS quantum dots on Chlamydomonas reinhardtii - nanoparticles or the free ions? ENVIRONMENTAL SCIENCE & TECHNOLOGY 2011; 45:7664-7669. [PMID: 21842898 DOI: 10.1021/es201193s] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
In order to properly assess the environmental risk of engineered nanoparticles (ENP), it is necessary to determine their fate (including dissolution, aggregation, and bioaccumulation) under representative environmental conditions. CdTe/CdS quantum dots (QD), such as those used in medical imaging, are known to release Cd(2+) due (mainly) to the dissolution of their outer shell. In this study, Chlamydomonas reinhardtii was exposed to either a soluble Cd salt or QD at similar concentrations of total Cd. Free Cd concentrations were measured using the Absence of Gradients and Nernstian Equilibrium Stripping technique. QD dissolution increased with decreasing pH and with increasing QD concentration. When exposed to QD, bioaccumulation was largely accounted for by dissolved Cd. Nonetheless, QD were shown to be taken up by the cells and to provoke unique biological effects. Whole transcriptome screening using RNA-Seq analysis showed that the free Cd and the QD had distinctly different biological effects.
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Affiliation(s)
- Rute F Domingos
- Département de Chimie, Université de Montréal, C.P. 6128, succursale Centre-ville, Montréal, Quebec H3C 3J7, Canada.
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Belyaeva OB, Litvin FF. Photoactive pigment—enzyme complexes of chlorophyll precursor in plant leaves. BIOCHEMISTRY (MOSCOW) 2007; 72:1458-77. [DOI: 10.1134/s0006297907130044] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Ledford HK, Chin BL, Niyogi KK. Acclimation to singlet oxygen stress in Chlamydomonas reinhardtii. EUKARYOTIC CELL 2007; 6:919-30. [PMID: 17435007 PMCID: PMC1951523 DOI: 10.1128/ec.00207-06] [Citation(s) in RCA: 138] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In an aerobic environment, responding to oxidative cues is critical for physiological adaptation (acclimation) to changing environmental conditions. The unicellular alga Chlamydomonas reinhardtii was tested for the ability to acclimate to specific forms of oxidative stress. Acclimation was defined as the ability of a sublethal pretreatment with a reactive oxygen species to activate defense responses that subsequently enhance survival of that stress. C. reinhardtii exhibited a strong acclimation response to rose bengal, a photosensitizing dye that produces singlet oxygen. This acclimation was dependent upon photosensitization and occurred only when pretreatment was administered in the light. Shifting cells from low light to high light also enhanced resistance to singlet oxygen, suggesting an overlap in high-light and singlet oxygen response pathways. Microarray analysis of RNA levels indicated that a relatively small number of genes respond to sublethal levels of singlet oxygen. Constitutive overexpression of either of two such genes, a glutathione peroxidase gene and a glutathione S-transferase gene, was sufficient to enhance singlet oxygen resistance. Escherichia coli and Saccharomyces cerevisiae exhibit well-defined responses to reactive oxygen but did not acclimate to singlet oxygen, possibly reflecting the relative importance of singlet oxygen stress for photosynthetic organisms.
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Affiliation(s)
- Heidi K Ledford
- Department of Plant and Microbial Biology, 111 Koshland Hall, University of California-Berkeley, Berkeley, CA 94720-3102, USA
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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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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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Yang J, Cheng Q. Origin and evolution of the light-dependent protochlorophyllide oxidoreductase (LPOR) genes. PLANT BIOLOGY (STUTTGART, GERMANY) 2004; 6:537-544. [PMID: 15375724 DOI: 10.1055/s-2004-821270] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Light-dependent NADPH-protochlorophyllide oxidoreductase (LPOR) is a nuclear-encoded chloroplast protein in green algae and higher plants which catalyzes the light-dependent reduction of protochlorophyllide to chlorophyllide. Light-dependent chlorophyll biosynthesis occurs in all oxygenic photosynthetic organisms. With the exception of angiosperms, this pathway coexists with a separate light-independent chlorophyll biosynthetic pathway, which is catalyzed by light-independent protochlorophyllide reductase (DPOR) in the dark. In contrast, the light-dependent function of chlorophyll biosynthesis is absent from anoxygenic photosynthetic bacteria. Consequently, the question is whether cyanobacteria are the ancestors of all organisms that conduct light-dependent chlorophyll biosynthesis. If so, how did photosynthetic eukaryotes acquire the homologous genes of LPOR in their nuclear genomes? The large number of complete genome sequences now available allow us to detect the evolutionary history of LPOR genes by conducting a genome-wide sequence comparison and phylogenetic analysis. Here, we show the results of a detailed phylogenetic analysis of LPOR and other functionally related enzymes in the short chain dehydrogenase/reductase (SDR) family. We propose that the LPOR gene originated in the cyanobacterial genome before the divergence of eukaryotic photosynthetic organisms. We postulated that the photosynthetic eukaryotes obtained their LPOR homologues through endosymbiotic gene transfer.
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Affiliation(s)
- J Yang
- College of Life Sciences, Peking University, Beijing 100871, China
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Abstract
Protochlorophyllide (Pchlide) reductases are key enzymes in the process of chlorophyll biosynthesis. In this review, current knowledge on the molecular organization, substrate specificity and assembly of the light-dependent reduced nicotinamide adenine dinucleotide phosphate:Pchlide oxidoreductases are discussed. Characteristics of light-independent enzymes are also described briefly, and the possible reasons for the selection of light-dependent enzymes during the course of evolution are discussed.
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Affiliation(s)
- Benoît Schoefs
- Laboratoire de Phytobiologie cellulaire, UMR-INRA/UB 1088, FRE-CNRS 2625-Plante Microbe Environnement, Université de Bourgogne à Dijon, Dijon, France
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Frick G, Su Q, Apel K, Armstrong GA. An Arabidopsis porB porC double mutant lacking light-dependent NADPH:protochlorophyllide oxidoreductases B and C is highly chlorophyll-deficient and developmentally arrested. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2003; 35:141-53. [PMID: 12848821 DOI: 10.1046/j.1365-313x.2003.01798.x] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
A key reaction in the biosynthesis of chlorophylls (Chls) a and b from cyanobacteria through higher plants is the strictly light-dependent reduction of protochlorophyllide (Pchlide) a to chlorophyllide (Chlide) a. Angiosperms, unlike other photosynthetic organisms, rely exclusively upon this mechanism to reduce Pchlide and hence require light to green. In Arabidopsis, light-dependent Pchlide reduction is mediated by three structurally related but differentially regulated NADPH:Pchlide oxidoreductases, denoted as PORA, PORB, and PORC. The PORA and PORB genes, but not PORC, are strongly expressed early in seedling development. In contrast, expression of PORB and PORC, but not PORA, is observed in older seedlings and adult plants. We have tested the hypothesis that PORB and PORC govern light-dependent Chl biosynthesis throughout most of the plant development by identifying porB and porC mutants of Arabidopsis, the first higher plant por mutants characterized. The porB-1 and porC-1 mutants lack the respective POR transcripts and specific POR isoforms because of the interruption of the corresponding genes by a derivative of the maize Dissociation (Ds) transposable element. Single por mutants, grown photoperiodically, display no obvious phenotypes at the whole plant or chloroplast ultrastructural levels, although the porB-1 mutant has less extensive etioplast inner membranes. However, a light-grown porB-1 porC-1 double mutant develops a seedling-lethal xantha phenotype at the cotyledon stage, contains only small amounts of Chl a, and possesses chloroplasts with mostly unstacked thylakoid membranes. PORB and PORC thus seem to play redundant roles in maintaining light-dependent Chl biosynthesis in green plants, and are together essential for growth and development.
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Affiliation(s)
- Geneviève Frick
- Institute for Plant Sciences, Plant Genetics, Swiss Federal Institute of Technology (ETH), Zürich, Switzerland
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Kathir P, LaVoie M, Brazelton WJ, Haas NA, Lefebvre PA, Silflow CD. Molecular map of the Chlamydomonas reinhardtii nuclear genome. EUKARYOTIC CELL 2003; 2:362-79. [PMID: 12684385 PMCID: PMC154841 DOI: 10.1128/ec.2.2.362-379.2003] [Citation(s) in RCA: 94] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2002] [Accepted: 12/10/2002] [Indexed: 11/20/2022]
Abstract
We have prepared a molecular map of the Chlamydomonas reinhardtii genome anchored to the genetic map. The map consists of 264 markers, including sequence-tagged sites (STS), scored by use of PCR and agarose gel electrophoresis, and restriction fragment length polymorphism markers, scored by use of Southern blot hybridization. All molecular markers tested map to one of the 17 known linkage groups of C. reinhardtii. The map covers approximately 1,000 centimorgans (cM). Any position on the C. reinhardtii genetic map is, on average, within 2 cM of a mapped molecular marker. This molecular map, in combination with the ongoing mapping of bacterial artificial chromosome (BAC) clones and the forthcoming sequence of the C. reinhardtii nuclear genome, should greatly facilitate isolation of genes of interest by using positional cloning methods. In addition, the presence of easily assayed STS markers on each arm of each linkage group should be very useful in mapping new mutations in preparation for positional cloning.
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Affiliation(s)
- Pushpa Kathir
- Department of Genetics, University of Minnesota, St. Paul, Minnesota, USA
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Harris EH. CHLAMYDOMONAS AS A MODEL ORGANISM. ANNUAL REVIEW OF PLANT PHYSIOLOGY AND PLANT MOLECULAR BIOLOGY 2001; 52:363-406. [PMID: 11337403 DOI: 10.1146/annurev.arplant.52.1.363] [Citation(s) in RCA: 430] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The unicellular green alga Chlamydomonas offers a simple life cycle, easy isolation of mutants, and a growing array of tools and techniques for molecular genetic studies. Among the principal areas of current investigation using this model system are flagellar structure and function, genetics of basal bodies (centrioles), chloroplast biogenesis, photosynthesis, light perception, cell-cell recognition, and cell cycle control. A genome project has begun with compilation of expressed sequence tag data and gene expression studies and will lead to a complete genome sequence. Resources available to the research community include wild-type and mutant strains, plasmid constructs for transformation studies, and a comprehensive on-line database.
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Affiliation(s)
- Elizabeth H Harris
- Developmental, Cell and Molecular Biology Group, Biology Department, Duke University, Durham, North Carolina 27708-1000; e-mail:
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Heyes DJ, Martin GE, Reid RJ, Hunter CN, Wilks HM. NADPH:protochlorophyllide oxidoreductase from Synechocystis: overexpression, purification and preliminary characterisation. FEBS Lett 2000; 483:47-51. [PMID: 11033354 DOI: 10.1016/s0014-5793(00)02081-0] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
NADPH:protochlorophyllide oxidoreductase (POR) catalyses the light-dependent reduction of protochlorophyllide to chlorophyllide, a key regulatory reaction in the chlorophyll biosynthetic pathway. POR from the cyanobacterium Synechocystis has been overproduced in Escherichia coli with a hexahistidine tag at the N-terminus. This enzyme (His(6)-POR) has been purified to homogeneity and a preliminary characterisation of its kinetic and substrate binding properties is presented. Chemical modification experiments have been used to demonstrate inhibition of POR activity by the thiol-specific reagent N-ethyl maleimide. Substrate protection experiments reveal that the modified Cys residues are involved in either substrate binding or catalysis.
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Affiliation(s)
- D J Heyes
- Krebs Institute for Biomolecular Research and Robert Hill Institute for Photosynthesis, Department of Molecular Biology and Biotechnology, The University of Sheffield, S10 2TN, Sheffield, UK
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22
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Moseley J, Quinn J, Eriksson M, Merchant S. The Crd1 gene encodes a putative di-iron enzyme required for photosystem I accumulation in copper deficiency and hypoxia in Chlamydomonas reinhardtii. EMBO J 2000; 19:2139-51. [PMID: 10811605 PMCID: PMC384357 DOI: 10.1093/emboj/19.10.2139] [Citation(s) in RCA: 153] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Chlamydomonas reinhardtii adapts to copper deficiency by degrading apoplastocyanin and inducing Cyc6 and Cpx1 encoding cytochrome c(6) and coproporphyrinogen oxidase, respectively. To identify other components in this pathway, colonies resulting from insertional mutagenesis were screened for copper- conditional phenotypes. Twelve crd (copper response defect) strains were identified. In copper-deficient conditions, the crd strains fail to accumulate photosystem I and light-harvesting complex I, and they contain reduced amounts of light-harvesting complex II. Cyc6, Cpx1 expression and plastocyanin accumulation remain copper responsive. The crd phenotype is rescued by a similar amount of copper as is required for repression of Cyc6 and Cpx1 and for maintenance of plastocyanin at its usual stoichiometry, suggesting that the affected gene is a target of the same signal transduction pathway. The crd strains represent alleles at a single locus, CRD1, which encodes a 47 kDa, hydrophilic protein with a consensus carboxylate-bridged di-iron binding site. Crd1 homologs are present in the genomes of photosynthetic organisms. In Chlamydomonas, Crd1 expression is activated in copper- or oxygen-deficient cells, and Crd1 function is required for adaptation to these conditions.
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Affiliation(s)
- J Moseley
- Department of Chemistry and Biochemistry and Molecular Biology Institute, University of California, Los Angeles, Los Angeles, CA 90095-1569, USA
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Armstrong GA. Greening in the dark: light-independent chlorophyll biosynthesis from anoxygenic photosynthetic bacteria to gymnosperms. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 1998. [DOI: 10.1016/s1011-1344(98)00063-3] [Citation(s) in RCA: 105] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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24
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Abstract
During this decade, there have been major advancements in the understanding of genetic loci involved in synthesis of the family of Mg-tetrapyrroles known as chlorophylls and bacteriochlorophylls. Molecular genetic analysis of Mg-tetrapyrrole biosynthesis was initiated by the performance of detailed sequence and mutational analysis of the photosynthesis gene cluster from Rhodobacter capsulatus. These studies provided the first detailed understanding of genes involved in bacteriochlorophyll a biosynthesis. In the short time since these studies were initiated, most of the chlorophyll biosynthesis genes have been identified by virtue of their ability to complement bacteriochlorophyll a biosynthesis mutants as well as by sequence homology comparisons. This review is centered on a discussion of our current understanding of bacterial, algal, and plant genes that code for enzymes in the Mg-branch of the tetrapyrrole biosynthetic pathway that are responsible for synthesis of chlorophylls and bacteriochlorophylls.
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Affiliation(s)
- J Y Suzuki
- Center for Gene Research, Nagoya University, Japan
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25
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[3] High-frequency nuclear transformation of Chlamydomonas reinhardtii. Methods Enzymol 1998. [DOI: 10.1016/s0076-6879(98)97005-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/21/2023]
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Kropat J, Oster U, Rüdiger W, Beck CF. Chlorophyll precursors are signals of chloroplast origin involved in light induction of nuclear heat-shock genes. Proc Natl Acad Sci U S A 1997; 94:14168-72. [PMID: 9391171 PMCID: PMC28451 DOI: 10.1073/pnas.94.25.14168] [Citation(s) in RCA: 202] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Coordination between the activities of organelles and the nucleus requires the exchange of signals. Using Chlamydomonas, we provide evidence that plastid-derived chlorophyll precursors may replace light in the induction of two nuclear heat-shock genes (HSP70A and HSP70B) and thus qualify as plastidic signal. Mutants defective in the synthesis of Mg-protoporphyrin IX were no longer inducible by light. Feeding of Mg-protoporphyrin IX or its dimethyl ester to wild-type or mutant cells in the dark resulted in induction. The analysis of HSP70A promoter mutants that do or do not respond to light revealed that these chlorophyll precursors specifically activate the light signaling pathway. Activation of gene expression was not observed when protoporphyrin IX, protochlorophyllide, or chlorophyllide were added. A specific interaction of defined chlorophyll precursors with factor(s) that regulate nuclear gene expression is suggested.
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Affiliation(s)
- J Kropat
- Institut fur Biologie III, Universitat Freiburg, Schanzlestrasse 1, D-79104 Freiburg, Germany
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27
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Li HH, Quinn J, Culler D, Girard-Bascou J, Merchant S. Molecular genetic analysis of plastocyanin biosynthesis in Chlamydomonas reinhardtii. J Biol Chem 1996; 271:31283-9. [PMID: 8940133 DOI: 10.1074/jbc.271.49.31283] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Five plastocyanin-deficient mutants were identified from a population of UV-mutagenized Chlamydomonas reinhardtii cells. Genetic complementation experiments indicated that four mutants represented alleles at the PCY1 locus (pcy1-2, pcy1-3, pcy1-4, and pcy1-5). Sequence analysis confirmed that two strains, pcy1-2 and pcy1-3, carry a frameshift (-1) and a nonsense mutation, respectively, while strains pcy1-4 and pcy1-5 synthesize an extended protein as a result of read-through mutations at the stop codon. The C-terminal extension does not affect synthesis or processing of the pre-proteins, but the polypeptides are rapidly degraded after the second (lumenal) processing event. The frameshift mutation in pcy1-2 results in loss of Pcy1 mRNA, as noted previously for strain ac208 (pcy1-1), but the abundance of Pcy1 mRNA in strain pcy1-3, which carries a nonsense mutation at codon 26, is unaffected relative to wild-type cells. The decreased abundance of frameshifted Pcy1 mRNA is attributed to increased degradation rather than decreased synthesis, since the mRNAs can be stabilized by treatment of cells with cycloheximide or anisomycin. The fifth strain has a wild-type plastocyanin-encoding gene, but the strain accumulates apoplastocyanin at the expense of holoplastocyanin. We suggest that the mutation identifies a new locus (PCY2) whose function is required for normal holoplastocyanin accumulation. Like ac208 (pcy1-1), several of the new mutants were suppressed spontaneously owing to accumulation of cytochrome c6 (a functional substitute for plastocyanin). The suppressor mutation(s) displayed Mendelian inheritance and segregated independently from the PCY1 locus, which confirms that regulation of Cyc6 expression is not tightly linked to plastocyanin function.
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Affiliation(s)
- H H Li
- Department of Chemistry and Biochemistry, UCLA, Los Angeles, California 90095-1569, USA
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