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Gu S, Dai X, Jiang J, Liu Y. Enhancing the catalytic activity of cyanobacterial chlorophyllase from Oscillatoria acuminata PCC 6304 through rational site-directed mutagenesis. Process Biochem 2022. [DOI: 10.1016/j.procbio.2022.01.023] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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2
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Sharafi E, Dehestani A, Farmani J, Parizi AP, Taheri‐Kafrani A. Chlorophyllase‐Catalyzed Chlorophyll Removal from Vegetable Oils Using Recombinant Eukaryotic and Prokaryotic Enzymes. J AM OIL CHEM SOC 2021. [DOI: 10.1002/aocs.12465] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Ebrahim Sharafi
- Genetics and Agricultural Biotechnology Institute of Tabarestan Sari Agricultural Sciences and Natural Resources University 578 Sari Iran
| | - Ali Dehestani
- Genetics and Agricultural Biotechnology Institute of Tabarestan Sari Agricultural Sciences and Natural Resources University 578 Sari Iran
| | - Jamshid Farmani
- Department of Food Science and Technology, Faculty of Agricultural Engineering Sari Agricultural Sciences and Natural Resources University 578 Sari Iran
| | - Ali Pakdin Parizi
- Genetics and Agricultural Biotechnology Institute of Tabarestan Sari Agricultural Sciences and Natural Resources University 578 Sari Iran
| | - Asghar Taheri‐Kafrani
- Department of Biotechnology, Faculty of Advanced Sciences and Technologies University of Isfahan Isfahan 81746‐73441 Iran
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Gu S, Dai X, Xu Z, Niu Q, Jiang J, Liu Y. Molecular, structural and biochemical characterization of a novel recombinant chlorophyllase from cyanobacterium Oscillatoria acuminata PCC 6304. Microb Cell Fact 2021; 20:14. [PMID: 33430874 PMCID: PMC7802212 DOI: 10.1186/s12934-020-01507-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Accepted: 12/29/2020] [Indexed: 11/26/2022] Open
Abstract
Background
Chlorophyllase catalyzes the hydrolysis of chlorophyll and produces chlorophyllide and phytol. Cyanobacterial chlorophyllases are likely to be more highly heterologously expressed than plant chlorophyllases. A novel recombinant chlorophyllase from the cyanobacterium Oscillatoria acuminata PCC 6304 was successfully expressed in Escherichia coli BL21(DE3). Results The putative N-terminal 28-amino-acid signal peptide sequence of O. acuminata chlorophyllase (OaCLH) is essential for its activity, but may confer poor solubility on OaCLH. The C-terminal fusion of a 6 × His tag caused a partial loss of activity in recombinant OaCLH, but an N-terminal 6 × His tag did not destroy its activity. The optimal pH and temperature for recombinant OaCLH activity are 7.0 and 40 °C, respectively. Recombinant OaCLH has hydrolysis activities against chlorophyll a, chlorophyll b, bacteriochlorophyll a, and pheophytin a, but prefers chlorophyll b and chlorophyll a as substrates. The results of site-directed mutagenesis experiments indicated that the catalytic triad of OaCLH consists of Ser159, Asp226, and His258. Conclusions The high-level expression and broad substrate specificity of recombinant OaCLH make it suitable for genetically engineering and a promising biocatalyst for industrial production, with applications in vegetable oil refining and laundry detergents.
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Affiliation(s)
- Sitian Gu
- State Key Laboratory of Food Science and Technology, Collaborative Innovation Center of Food Safety and Quality Control in Jiangsu Province, National Engineering Research Center for Functional Food, National Engineering Laboratory for Cereal Fermentation Technology, School of Food Science and Technology, Jiangnan University, 1800 Lihu Road, Jiangsu, 214122, Wuxi, People's Republic of China. .,Wilmar Biotechnology Research & Development Center Co., Ltd, 200137, Shanghai, People's Republic of China.
| | - Xiaojun Dai
- Wilmar Biotechnology Research & Development Center Co., Ltd, 200137, Shanghai, People's Republic of China
| | - Zhengjun Xu
- Wilmar Biotechnology Research & Development Center Co., Ltd, 200137, Shanghai, People's Republic of China
| | - Qiwen Niu
- Wilmar Biotechnology Research & Development Center Co., Ltd, 200137, Shanghai, People's Republic of China
| | - Jiang Jiang
- State Key Laboratory of Food Science and Technology, Collaborative Innovation Center of Food Safety and Quality Control in Jiangsu Province, National Engineering Research Center for Functional Food, National Engineering Laboratory for Cereal Fermentation Technology, School of Food Science and Technology, Jiangnan University, 1800 Lihu Road, Jiangsu, 214122, Wuxi, People's Republic of China
| | - Yuanfa Liu
- State Key Laboratory of Food Science and Technology, Collaborative Innovation Center of Food Safety and Quality Control in Jiangsu Province, National Engineering Research Center for Functional Food, National Engineering Laboratory for Cereal Fermentation Technology, School of Food Science and Technology, Jiangnan University, 1800 Lihu Road, Jiangsu, 214122, Wuxi, People's Republic of China.
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Yen CC, Chuang YC, Ko CY, Chen LFO, Chen SS, Lin CJ, Chou YL, Shaw JF. Immobilization of Chlamydomonas reinhardtii CLH1 on APTES-Coated Magnetic Iron Oxide Nanoparticles and Its Potential in the Production of Chlorophyll Derivatives. Molecules 2016; 21:molecules21080972. [PMID: 27472309 PMCID: PMC6273557 DOI: 10.3390/molecules21080972] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2016] [Revised: 07/18/2016] [Accepted: 07/21/2016] [Indexed: 11/16/2022] Open
Abstract
Recombinant Chlamydomonas reinhardtii chlorophyllase 1 (CrCLH1) that could catalyze chlorophyll hydrolysis to chlorophyllide and phytol in vitro was successfully expressed in Escherichia coli. The recombinant CrCLH1 was immobilized through covalent binding with a cubic (3-aminopropyl) triethoxysilane (APTES) coating on magnetic iron oxide nanoparticles (MIONPs), which led to markedly improved enzyme performance and decreased biocatalyst costs for potential industrial application. The immobilized enzyme exhibited a high immobilization yield (98.99 ± 0.91 mg/g of gel) and a chlorophyllase assay confirmed that the immobilized recombinant CrCLH1 retained enzymatic activity (722.3 ± 50.3 U/g of gel). Biochemical analysis of the immobilized enzyme, compared with the free enzyme, showed higher optimal pH and pH stability for chlorophyll-a hydrolysis in an acidic environment (pH 3-5). In addition, compared with the free enzyme, the immobilized enzyme showed higher activity in chlorophyll-a hydrolysis in a high temperature environment (50-60 °C). Moreover, the immobilized enzyme retained a residual activity of more than 64% of its initial enzyme activity after 14 cycles in a repeated-batch operation. Therefore, APTES-coated MIONP-immobilized recombinant CrCLH1 can be repeatedly used to lower costs and is potentially useful for the industrial production of chlorophyll derivatives.
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Affiliation(s)
- Chih-Chung Yen
- Institute of Genomics and Bioinformatics, National Chung Hsing University, Taichung 40227, Taiwan.
- Agricultural Biotechnology Center, National Chung Hsing University, Taichung 40227, Taiwan.
| | - Yao-Chen Chuang
- Institute of Biomedical Engineering and Nanomedicine, National Health Research Institutes, Miaoli 35053, Taiwan.
| | - Chia-Yun Ko
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei 11529, Taiwan.
| | - Long-Fang O Chen
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei 11529, Taiwan.
| | - Sheau-Shyang Chen
- Department of Biological Science & Technology, I-Shou University, Kaohsiung 840, Taiwan.
| | - Chia-Jung Lin
- Department of Biological Science & Technology, I-Shou University, Kaohsiung 840, Taiwan.
| | - Yi-Li Chou
- Department of Biological Science & Technology, I-Shou University, Kaohsiung 840, Taiwan.
| | - Jei-Fu Shaw
- Agricultural Biotechnology Center, National Chung Hsing University, Taichung 40227, Taiwan.
- Department of Biological Science & Technology, I-Shou University, Kaohsiung 840, Taiwan.
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5
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Chou YL, Ko CY, Yen CC, Chen LFO, Shaw JF. A Novel Recombinant Chlorophyllase1 from Chlamydomonas reinhardtii for the Production of Chlorophyllide Derivatives. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2015; 63:9496-9503. [PMID: 26478543 DOI: 10.1021/acs.jafc.5b02787] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Natural chlorophyll metabolites have exhibited physiological activity in vitro. In this study, a recombinant chlorophyllase1 gene from Chlamydomonas reinhardtii (CrCLH1) was isolated and characterized. Recombinant CrCLH1 can perform chlorophyll dephytylation and produce chlorophyllide and phytol. In a transient assay, the subcellular localization of CrCLH1-green fluorescent protein was determined to be outside the chloroplast. Biochemical analyses of the activity of recombinant CrCLH1 indicated that its optimal pH value and temperature are 6.0 and 40 °C, respectively. Enzyme kinetic data revealed that the recombinant CrCLH1 had a higher catalytic efficiency for chlorophyll a than for chlorophyll b and bacteriochlorophyll a. According to high-performance liquid chromatography analysis of chlorophyll hydrolysis, recombinant CrCLH1 catalyzed the conversion of chlorophyll a to pheophorbide a at pH 5. Therefore, recombinant CrCLH1 can be used as a biocatalyst to produce chlorophyllide derivatives.
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Affiliation(s)
- Yi-Li Chou
- Department of Biological Science and Technology, I-Shou University , Kaohsiung 82445, Taiwan
| | - Chia-Yun Ko
- Institute of Plant and Microbial Biology, Academia Sinica , Taipei 11529, Taiwan
| | - Chih-Chung Yen
- Institute of Genomics and Bioinformatics, National Chung Hsing University , Taichung 40227, Taiwan
- Agricultural Biotechnology Center, National Chung Hsing University , Taichung 40227, Taiwan
| | - Long-Fang O Chen
- Institute of Plant and Microbial Biology, Academia Sinica , Taipei 11529, Taiwan
| | - Jei-Fu Shaw
- Department of Biological Science and Technology, I-Shou University , Kaohsiung 82445, Taiwan
- Agricultural Biotechnology Center, National Chung Hsing University , Taichung 40227, Taiwan
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Lee GC, Chepyshko H, Chen HH, Chu CC, Chou YF, Akoh CC, Shaw JF. Genes and biochemical characterization of three novel chlorophyllase isozymes from Brassica oleracea. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2010; 58:8651-8657. [PMID: 20681655 DOI: 10.1021/jf1016384] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Three full length cDNAs (BoCLH1, 1140 bp; BoCLH2, 1104 bp; BoCLH3, 884 bp) encoding putative chlorophyllases were cloned from the cDNA pools of broccoli (Brassica oleracea) florets and characterized. The amino acid sequence analysis indicated that these three BoCLHs contained a highly conserved lipase motif (GXSXG). However, only BoCLH3 lacked the His residue which is the component of the catalytic triad (Ser-His-Asp). N-terminal sequences of BoCLH1 and BoCLH2 were predicted to have typical signal sequences for the chloroplast, whereas the plasma membrane-targeting sequence was identified in BoCLH3. The predicted molecular masses of BoCLH1, 2, and 3 were 34.7, 35.3, and 23.5 kDa, respectively. The recombinant BoCLHs were successfully expressed in Escherichia coli for the biochemical characterization. The recombinant BoCLH3 showed very low chlorophyllase activity possibly due to its incomplete catalytic triad. BoCLH1 and BoCLH2 showed significant differences in biochemical properties such as pH stability and temperature optimum. Kinetic analysis revealed that BoCLH1 preferably hydrolyzed Mg-free chlorophyll, while BoCLH2 hydrolyzed both chlorophyll and Mg-free chlorophyll at a similar level. Different characteristics between BoCLH1 and BoCLH2 implied that they may have different physiological functions in broccoli. The catalytic triad of recombinant BoCLH2 was identified as Ser141, His247, and Asp170 by site-directed mutagenesis. It suggested that the three broccoli chlorophyllase isozymes were serine hydrolases.
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Affiliation(s)
- Guan-Chiun Lee
- Department of Life Science, National Taiwan Normal University, Taipei, Taiwan
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Optimization of Chlorophyllase-catalyzed Hydrolysis of Chlorophyll in Monophasic Organic Solvent Media. Appl Biochem Biotechnol 2007; 142:263-75. [DOI: 10.1007/s12010-007-0021-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2005] [Revised: 07/19/2006] [Accepted: 07/21/2006] [Indexed: 11/25/2022]
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Arkus KAJ, Jez JM. Development of a high-throughput purification method and a continuous assay system for chlorophyllase. Anal Biochem 2006; 353:93-8. [PMID: 16643837 DOI: 10.1016/j.ab.2006.03.034] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2005] [Revised: 03/03/2006] [Accepted: 03/20/2006] [Indexed: 11/16/2022]
Abstract
In the degradation of chlorophyll, chlorophyllase catalyzes the initial hydrolysis of the phytol moiety from the pigment. Since chlorophyll degradation is a defining feature of plant senescence, compounds inhibiting chlorophyllase activity may delay senescence, thereby improving shelf life and appearance of plant products. Here we describe the development of a 96-well plate-based purification and assay system for measuring chlorophyllase activity. Integrated lysis and immobilized metal affinity chromatography plates were used for purifying recombinant hexahistidine-tagged Triticum aestivum (wheat) chlorophyllase from Escherichia coli. Chlorophyllase assays using chlorophyll as a substrate showed that the immobilized fusion protein displayed kinetic parameters similar to those of recombinant enzyme purified by affinity chromatography; however, the need to extract reaction products from a multiwell plate limits the value of this assay for high-throughput screening applications. Replacing chlorophyll with p-nitrophenyl-ester substrates eliminates the extraction step and allows for continuous measurement of chlorophyllase activity in a multiwell plate format. Determination of steady state kinetic constants, pH rate profile, the inhibitory effects of metal ions and esterase inhibitors, and the effect of functional group-modifying reagents validated the utility of the plate-based system. The combined purification and assay system provides a convenient and rapid method for the assessment of chlorophyllase activity.
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Affiliation(s)
- Kiani A J Arkus
- Donald Danforth Plant Science Center, St. Louis, MO 63132, USA
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9
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Arkus KAJ, Cahoon EB, Jez JM. Mechanistic analysis of wheat chlorophyllase. Arch Biochem Biophys 2005; 438:146-55. [PMID: 15913540 DOI: 10.1016/j.abb.2005.04.019] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2005] [Revised: 04/25/2005] [Accepted: 04/25/2005] [Indexed: 11/17/2022]
Abstract
Chlorophyllase catalyzes the initial step in the degradation of chlorophyll and plays a key role in leaf senescence and fruit ripening. Here, we report the cloning of chlorophyllase from Triticum aestivum (wheat) and provide a detailed mechanistic analysis of the enzyme. Purification of recombinant chlorophyllase from an Escherichia coli expression system indicates that the enzyme functions as a dimeric protein. Wheat chlorophyllase hydrolyzed the phytol moiety from chlorophyll (k(cat) = 566 min(-1); K(m) = 63 microM) and was active over a broad temperature range (10-75 degrees C). In addition, the enzyme displays carboxylesterase activity toward p-nitrophenyl (PNP)-butyrate, PNP-decanoate, and PNP-palmitate. The pH-dependence of the reaction showed the involvement of an active site residue with a pK(a) of approximately 6.5 for both k(cat) and k(cat)/K(m) with chlorophyll, PNP-butyrate, and PNP-decanoate. Using these substrates, solvent kinetic isotope effects ranging from 1.5 to 1.9 and from 1.4 to 1.9 on k(cat) and k(cat)/K(m), respectively, were observed. Proton inventory experiments suggest the transfer of a single proton in the rate-limiting step. Our analysis of wheat chlorophyllase indicates that the enzyme uses a charge-relay mechanism similar to other carboxylesterases for catalysis. Understanding the activity and mechanism of chlorophyllase provides insight on the biological and chemical control of senescence in plants and lays the groundwork for biotechnological improvement of this enzyme.
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Affiliation(s)
- Kiani A J Arkus
- Donald Danforth Plant Science Center, St. Louis, MO 63132, USA
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10
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Tsuchiya T, Suzuki T, Yamada T, Shimada H, Masuda T, Ohta H, Takamiya KI. Chlorophyllase as a serine hydrolase: identification of a putative catalytic triad. PLANT & CELL PHYSIOLOGY 2003; 44:96-101. [PMID: 12552153 DOI: 10.1093/pcp/pcg011] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Chlorophyllases (Chlases), cloned so far, contain a lipase motif with the active serine residue of the catalytic triad of triglyceride lipases. Inhibitors specific for the catalytic serine residue in serine hydrolases, which include lipases effectively inhibited the activity of the recombinant Chenopodium album Chlase (CaCLH). From this evidence we assumed that the catalytic mechanism of hydrolysis by Chlase might be similar to those of serine hydrolases that have a catalytic triad composed of serine, histidine and aspartic acid in their active site. Thus, we introduced mutations into the putative catalytic residue (Ser162) and conserved amino acid residues (histidine, aspartic acid and cysteine) to generate recombinant CaCLH mutants. The three amino acid residues (Ser162, Asp191 and His262) essential for Chlase activity were identified. These results indicate that Chlase is a serine hydrolase and, by analogy with a plausible catalytic mechanism of serine hydrolases, we proposed a mechanism for hydrolysis catalyzed by Chlase.
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Affiliation(s)
- Tohru Tsuchiya
- Department of Biological Sciences, Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, Nagatsuta, Midori-ku, Yokohama, Kanagawa, 226-8501 Japan.
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11
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Yi Y, Kermasha S, L’Hocine L, Neufeld R. Encapsulation of chlorophyllase in hydrophobically modified hydrogel. ACTA ACUST UNITED AC 2002. [DOI: 10.1016/s1381-1177(02)00182-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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12
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Takamiya KI, Tsuchiya T, Ohta H. Degradation pathway(s) of chlorophyll: what has gene cloning revealed? TRENDS IN PLANT SCIENCE 2000; 5:426-31. [PMID: 11044719 DOI: 10.1016/s1360-1385(00)01735-0] [Citation(s) in RCA: 95] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
The mechanism responsible for the degreening of plants and the degradation of chlorophyll was unclear for many years. However, recent studies have identified the colorless intermediates and helped to construct a basic pathway for degradation. After the successive removal of phytol and Mg21 from the chlorophyll molecule by chlorophyllase and 'Mg dechelatase', pheophorbide a is cleaved and reduced to yield a colorless, open tetrapyrrole intermediate. After further modifications, this is finally transported to the vacuole. Cloning the genes for chlorophyllase isozymes and the reductase should help to elucidate the physiological roles of each enzyme at a molecular level.
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Affiliation(s)
- K I Takamiya
- Dept of Biological Sciences, Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, Nagatsuta 4259, Midori-ku, Yokohama 226-8501, Japan
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Tsuchiya T, Ohta H, Okawa K, Iwamatsu A, Shimada H, Masuda T, Takamiya K. Cloning of chlorophyllase, the key enzyme in chlorophyll degradation: finding of a lipase motif and the induction by methyl jasmonate. Proc Natl Acad Sci U S A 1999; 96:15362-7. [PMID: 10611389 PMCID: PMC24824 DOI: 10.1073/pnas.96.26.15362] [Citation(s) in RCA: 253] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/1999] [Accepted: 10/21/1999] [Indexed: 11/18/2022] Open
Abstract
Chlorophyllase (Chlase) is the first enzyme involved in chlorophyll (Chl) degradation and catalyzes the hydrolysis of ester bond to yield chlorophyllide and phytol. In the present study, we isolated the Chlase cDNA. We synthesized degenerate oligo DNA probes based on the internal amino acid sequences of purified Chlase from Chenopodium album, screened the C. album cDNA library, and cloned a cDNA (CaCLH, C. album chlorophyll-chlorophyllido hydrolase). The deduced amino acid sequence (347 aa residues) had a lipase motif overlapping with an ATP/GTP-binding motif (P-loop). CaCLH possibly was localized in the extraplastidic part of the cell, because a putative signal sequence for endoplasmic reticulum is at the N terminus. The amino acid sequence shared 37% identity with a function-unknown gene whose mRNA is inducible by coronatine and methyl jasmonate (MeJA) in Arabidopsis thaliana (AtCLH1). We expressed the gene products of AtCLH1 and of CaCLH in Escherichia coli, and they similarly exhibited Chlase activity. Moreover, we isolated another full-length cDNA based on an Arabidopsis genomic fragment and expressed it in E. coli, demonstrating the presence of the second Arabidopsis CLH gene (AtCLH2). No typical feature of signal sequence was identified in AtCLH1, whereas AtCLH2 had a typical signal sequence for chloroplast. AtCLH1 mRNA was induced rapidly by a treatment of MeJA, which is known to promote senescence and Chl degradation in plants, and a high mRNA level was maintained up to 9 h. AtCLH2, however, did not respond to MeJA.
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Affiliation(s)
- T Tsuchiya
- Department of Biological Sciences, Faculty of Bioscience and Biotechnology, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama, Kanagawa 226-8501, Japan
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Abstract
Although the loss of green color in senescent leaves and ripening fruits is a spectacular natural phenomenon, research on chlorophyll breakdown has been largely neglected until recently. This review summarizes knowledge about the fate of chlorophyll in degreening tissues that has been gained during the past few years. Structures of end- and intermediary products of degradation as well as the biochemistry of the porphyrin-cleaving reaction have been elucidated. The intracellular localization of the catabolic pathway is particularly important in the regulation of chlorophyll breakdown. None of the genes encoding the related catabolic enzymes has so far been isolated, which makes chlorophyll degradation an area of opportunity for future research.
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Affiliation(s)
- Philippe Matile
- University of Zurich, Institute of Plant Biology, Zollikerstrasse 107, Zurich, CH 8008 Switzerland; e-mail: , Cell Biology Department, Institute of Grassland and Environmental Research, Plas Gogerddan, Aberystwyth, Ceredigion, SY23 3EB, United Kingdom; e-mail:
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Apt KE, Kroth-Pancic PG, Grossman AR. Stable nuclear transformation of the diatom Phaeodactylum tricornutum. MOLECULAR & GENERAL GENETICS : MGG 1996; 252:572-9. [PMID: 8914518 DOI: 10.1007/bf02172403] [Citation(s) in RCA: 126] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
A nuclear transformation system has been developed for the diatom Phaeodactylum tricornutum using microparticle bombardment to introduce the sh ble gene from Streptoalloteichus hindustanus into cells. The sh ble gene encodes a protein that confers resistance to the antibiotics Zeocin and phleomycin. Chimeric genes containing promoter and terminator sequences from the P. tricornutum fcp genes were used to drive expression of sh ble. Between 10-100 transformants were recovered/10(8) cells. Transformants were able to grow on at least 500 micrograms/ml of Zeocin, which is 10 times the amount necessary to kill wild-type cells. Based on Southern hybridizations the sh ble gene was present in 1-3 copies/transformant. Relative levels of correctly processed transcripts were correlated with the abundance of the Sh ble protein (present at 0.1-2.0 micrograms/mg total protein). The cat reporter gene fused to a fcp promoter could also be introduced by microparticle bombardment and was found to be highly expressed (average of 7.1 U/mg total protein). This work demonstrates that heterologous genes can be readily expressed in P. tricornutum. The development of selectable marker and reporter gene constructs provides the tools necessary for dissecting gene structure and regulation, and introducing novel functions into diatoms.
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Affiliation(s)
- K E Apt
- Carnegie Institution of Washington, Department of Plant Biology, Stanford, CA 94305, USA
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