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Frascogna F, Ledermann B, Hartmann J, Pérez Patallo E, Zeqiri F, Hofmann E, Frankenberg-Dinkel N. On the evolution of the plant phytochrome chromophore biosynthesis. PLANT PHYSIOLOGY 2023; 193:246-258. [PMID: 37311159 DOI: 10.1093/plphys/kiad327] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Revised: 05/25/2023] [Accepted: 05/29/2023] [Indexed: 06/15/2023]
Abstract
Phytochromes are biliprotein photoreceptors present in plants, algae, certain bacteria, and fungi. Land plant phytochromes use phytochromobilin (PΦB) as the bilin chromophore. Phytochromes of streptophyte algae, the clade within which land plants evolved, employ phycocyanobilin (PCB), leading to a more blue-shifted absorption spectrum. Both chromophores are synthesized by ferredoxin-dependent bilin reductases (FDBRs) starting from biliverdin IXα (BV). In cyanobacteria and chlorophyta, BV is reduced to PCB by the FDBR phycocyanobilin:ferredoxin oxidoreductase (PcyA), whereas, in land plants, BV is reduced to PФB by phytochromobilin synthase (HY2). However, phylogenetic studies suggested the absence of any ortholog of PcyA in streptophyte algae and the presence of only PФB biosynthesis-related genes (HY2). The HY2 of the streptophyte alga Klebsormidium nitens (formerly Klebsormidium flaccidum) has already indirectly been indicated to participate in PCB biosynthesis. Here, we overexpressed and purified a His6-tagged variant of K. nitens HY2 (KflaHY2) in Escherichia coli. Employing anaerobic bilin reductase activity assays and coupled phytochrome assembly assays, we confirmed the product and identified intermediates of the reaction. Site-directed mutagenesis revealed 2 aspartate residues critical for catalysis. While it was not possible to convert KflaHY2 into a PΦB-producing enzyme by simply exchanging the catalytic pair, the biochemical investigation of 2 additional members of the HY2 lineage enabled us to define 2 distinct clades, the PCB-HY2 and the PΦB-HY2 clade. Overall, our study gives insight into the evolution of the HY2 lineage of FDBRs.
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Affiliation(s)
- Federica Frascogna
- Department of Microbiology, University of Kaiserslautern-Landau, Kaiserslautern 67663, Germany
| | - Benjamin Ledermann
- Department of Microbiology, University of Kaiserslautern-Landau, Kaiserslautern 67663, Germany
| | - Jana Hartmann
- Department of Microbiology, University of Kaiserslautern-Landau, Kaiserslautern 67663, Germany
| | - Eugenio Pérez Patallo
- Department of Microbiology, University of Kaiserslautern-Landau, Kaiserslautern 67663, Germany
| | - Fjoralba Zeqiri
- Protein Crystallography, Faculty of Biology and Biotechnology, Ruhr University Bochum, Bochum 44780, Germany
| | - Eckhard Hofmann
- Protein Crystallography, Faculty of Biology and Biotechnology, Ruhr University Bochum, Bochum 44780, Germany
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Zheng T, Wang M, Zhan J, Sun W, Yang Q, Lin Z, Bu T, Tang Z, Li C, Yan J, Shan Z, Chen H. Ferrous iron-induced increases in capitate glandular trichome density and upregulation of CbHO-1 contributes to increases in blinin content in Conyza blinii. PLANTA 2020; 252:81. [PMID: 33037484 DOI: 10.1007/s00425-020-03492-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Accepted: 10/04/2020] [Indexed: 06/11/2023]
Abstract
Ferrous iron can promote the development of glandular trichomes and increase the content of blinin, which depends on CbHO-1 expression. Conyza blinii (C. blinii) is a unique Chinese herbal medicine that grows in Sichuan Province, China. Because the habitat of C. blinii is an iron ore mining area with abundant iron content, this species can be used as one of the best materials to study the mechanism of plant tolerance to iron. In this study, C. blinii was treated with ferrous-EDTA solutions at different concentrations, and it was found that the tolerance value of C. blinii to iron was 200 μM. Under this concentration, the plant height, root length, biomass, and iron content of C. blinii increased to the maximum values, and the effect was dependent on the upregulated expression of CbHO-1. At the same time, under ferrous iron, the photosynthetic capacity and capitate glandular trichome density of C. blinii also significantly increased, providing precursors and sites for the synthesis of blinin, thus significantly increasing the content of blinin. These processes were also dependent on the high expression of CbHO-1. Correlation analysis showed that there were strong positive correlations between iron content, capitate glandular trichome density, CbHO-1 gene expression, and blinin content. This study explored the effects of ferrous iron on the physiology and biochemistry of C. blinii, greatly improving our understanding of the mechanism of iron tolerance in C. blinii.
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Affiliation(s)
- Tianrun Zheng
- College of Life Science, Sichuan Agricultural University, Ya'an, China
| | - Maojia Wang
- College of Life Science, Sichuan Agricultural University, Ya'an, China
| | - Junyi Zhan
- College of Life Science, Sichuan Agricultural University, Ya'an, China
| | - Wenjun Sun
- College of Life Science, Sichuan Agricultural University, Ya'an, China
| | - Qin Yang
- College of Life Science, Sichuan Agricultural University, Ya'an, China
| | - Zhiyi Lin
- College of Life Science, Sichuan Agricultural University, Ya'an, China
| | - Tongliang Bu
- College of Life Science, Sichuan Agricultural University, Ya'an, China
| | - Zizhong Tang
- College of Life Science, Sichuan Agricultural University, Ya'an, China
| | - Chenglei Li
- College of Life Science, Sichuan Agricultural University, Ya'an, China
| | - Jun Yan
- Key Laboratory of Coarse Cereal Processing, Ministry of Agriculture Rural Affairs, School of Food and Bioengineering, Chengdu University, Chengdu, China
| | - Zhi Shan
- College of Life Science, Sichuan Agricultural University, Ya'an, China
| | - Hui Chen
- College of Life Science, Sichuan Agricultural University, Ya'an, China.
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Puzorjov A, McCormick AJ. Phycobiliproteins from extreme environments and their potential applications. JOURNAL OF EXPERIMENTAL BOTANY 2020; 71:3827-3842. [PMID: 32188986 DOI: 10.1093/jxb/eraa139] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2019] [Accepted: 03/13/2020] [Indexed: 05/18/2023]
Abstract
The light-harvesting phycobilisome complex is an important component of photosynthesis in cyanobacteria and red algae. Phycobilisomes are composed of phycobiliproteins, including the blue phycobiliprotein phycocyanin, that are considered high-value products with applications in several industries. Remarkably, several cyanobacteria and red algal species retain the capacity to harvest light and photosynthesise under highly selective environments such as hot springs, and flourish in extremes of pH and elevated temperatures. These thermophilic organisms produce thermostable phycobiliproteins, which have superior qualities much needed for wider adoption of these natural pigment-proteins in the food, textile, and other industries. Here we review the available literature on the thermostability of phycobilisome components from thermophilic species and discuss how a better appreciation of phycobiliproteins from extreme environments will benefit our fundamental understanding of photosynthetic adaptation and could provide a sustainable resource for several industrial processes.
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Affiliation(s)
- Anton Puzorjov
- SynthSys and Institute of Molecular Plant Sciences, School of Biological Sciences, University of Edinburgh, Edinburgh, UK
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Aras M, Hartmann V, Hartmann J, Nowaczyk MM, Frankenberg-Dinkel N. Proximity channeling during cyanobacterial phycoerythrobilin synthesis. FEBS J 2019; 287:284-294. [PMID: 31319014 DOI: 10.1111/febs.15003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2019] [Revised: 06/17/2019] [Accepted: 07/16/2019] [Indexed: 11/30/2022]
Abstract
Substrate channeling is a widespread mechanism in metabolic pathways to avoid decomposition of unstable intermediates, competing reactions, and to accelerate catalytic turnover. During the biosynthesis of light-harvesting phycobilins in cyanobacteria, two members of the ferredoxin-dependent bilin reductases are involved in the reduction of the open-chain tetrapyrrole biliverdin IXα to the pink pigment phycoerythrobilin. The first reaction is catalyzed by 15,16-dihydrobiliverdin:ferredoxin oxidoreductase and produces the unstable intermediate 15,16-dihydrobiliverdin (DHBV). This intermediate is subsequently converted by phycoerythrobilin:ferredoxin oxidoreductase to the final product phycoerythrobilin. Although substrate channeling has been postulated already a decade ago, detailed experimental evidence was missing. Using a new on-column assay employing immobilized enzyme in combination with UV-Vis and fluorescence spectroscopy revealed that both enzymes transiently interact and that transfer of the intermediate is facilitated by a significantly higher binding affinity of DHBV toward phycoerythrobilin:ferredoxin oxidoreductase. Concluding from the presented data, the intermediate DHBV is transferred via proximity channeling.
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Affiliation(s)
- Marco Aras
- Fachbereich Biologie, Abteilung für Mikrobiologie, Technische Universität Kaiserslautern, Germany
| | - Volker Hartmann
- Cyanobakterielle Membranprotein Komplexe, Fakultät für Biologie und Biotechnologie, Ruhr-Universität Bochum, Germany
| | - Jana Hartmann
- Fachbereich Biologie, Abteilung für Mikrobiologie, Technische Universität Kaiserslautern, Germany
| | - Marc M Nowaczyk
- Cyanobakterielle Membranprotein Komplexe, Fakultät für Biologie und Biotechnologie, Ruhr-Universität Bochum, Germany
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5
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Mahawar L, Shekhawat GS. Haem oxygenase: A functionally diverse enzyme of photosynthetic organisms and its role in phytochrome chromophore biosynthesis, cellular signalling and defence mechanisms. PLANT, CELL & ENVIRONMENT 2018; 41:483-500. [PMID: 29220548 DOI: 10.1111/pce.13116] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2017] [Revised: 05/26/2017] [Accepted: 11/23/2017] [Indexed: 05/08/2023]
Abstract
Haem oxygenase (HO) is a universal enzyme that catalyses stereospecific cleavage of haem to BV IX α and liberates Fe+2 ion and CO as by-product. Beside haem degradation, it has important functions in plants that include cellular defence, stomatal regulation, iron mobilization, phytochrome chromophore synthesis, and lateral root formation. Phytochromes are an extended family of photoreceptors with a molecular mass of 250 kDa and occur as a dimer made up of 2 equivalent subunits of 125 kDa each. Each subunit is made of two components: the chromophore, a light-capturing pigment molecule and the apoprotein. Biosynthesis of phytochrome (phy) chromophore includes the oxidative splitting of haem to biliverdin IX by an enzyme HO, which is the decisive step in the biosynthesis. In photosynthetic organisms, BVα is reduced to 3Z PΦB by a ferredoxin-dependent PΦB synthase that finally isomerised to PΦB. The synthesized PΦB assembles with the phytochrome apoprotein in the cytoplasm to generate holophytochrome. Thus, necessary for photomorphogenesis in plants, which has confirmed from the genetic studies, conducted on Arabidopsis thaliana and pea. Besides the phytochrome chromophore synthesis, the review also emphasises on the current advances conducted in plant HO implying its developmental and defensive role.
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Affiliation(s)
- Lovely Mahawar
- Department of Botany, Jai Narain Vyas University, Jodhpur, 342001, India
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Yu P, Wu Y, Wang G, Jia T, Zhang Y. Purification and bioactivities of phycocyanin. Crit Rev Food Sci Nutr 2016; 57:3840-3849. [DOI: 10.1080/10408398.2016.1167668] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Affiliation(s)
- Ping Yu
- College of Food Science and Biotechnology, Zhejiang Gongshang University, Hangzhou, Zhejiang Province, P.R. China
| | - Yunting Wu
- College of Food Science and Biotechnology, Zhejiang Gongshang University, Hangzhou, Zhejiang Province, P.R. China
| | - Guangwei Wang
- College of Food Science and Biotechnology, Zhejiang Gongshang University, Hangzhou, Zhejiang Province, P.R. China
| | - Tianmei Jia
- College of Food Science and Biotechnology, Zhejiang Gongshang University, Hangzhou, Zhejiang Province, P.R. China
| | - Yishu Zhang
- College of Food Science and Biotechnology, Zhejiang Gongshang University, Hangzhou, Zhejiang Province, P.R. China
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Rajamani K, Renju VC, Sethupathy S, Thirugnanasambandan SS. Ameliorative effect of polyphenols from Padina boergesenii against ferric nitrilotriacetate induced renal oxidative damage: With inhibition of oxidative hemolysis and in vitro free radicals. ENVIRONMENTAL TOXICOLOGY 2015; 30:865-76. [PMID: 24458998 DOI: 10.1002/tox.21951] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2013] [Revised: 12/28/2013] [Accepted: 01/08/2014] [Indexed: 06/03/2023]
Abstract
The aim of this study was to evaluate the antioxidant activities of diethyl ether (DEE) and methanol (M) extracts from brown alga Padina boergesenii using in vitro and in vivo antioxidant assay, which may help to relate the antioxidant properties with the possible outline of its ameliorative effect. M extract showed higher radical scavenging activity through ferric reducing antioxidant power 139.11 µmol tannic acid equivalent/g; DPPH 71.32 ± 0.56%; deoxyribose radical 88.31 ± 0.47%, and total antioxidant activity 0.47 ± 0.02 mg ascorbic acid equivalents/g. Oxidative red blood cell (RBC) hemolysis inhibition rate was significantly higher in M extract (150 mg/kg body weight) in reference to total phenolic content (r = 0.935). Rats administered with DEE and M extracts (150 mg/kg body weight) for seven days before the administration of ferric nitrilotriacetate (9 mg of Fe/mg/kg bodyweight). Rats pretreated with extracts significantly changed the level of renal microsomal lipid peroxidation, glutathione, and antioxidant enzymes in post-mitochondrial supernatant (P < 0.05). Ameliorative effect of extracts against renal oxidative damage was evident in rat kidney through changes in necrotic and epithelial cells. HPTLC technique has identified the presence of rutin with reference to retardation factor (Rf ) in both the extracts. These findings support the source of polyphenols (rutin) from P. boergesenii had potent antioxidant activity; further work on isolation of bioactive compounds can be channeled to develop as a natural antioxidant.
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Affiliation(s)
- Karthikeyan Rajamani
- Department of Marine Sciences, Centre of Advanced Study in Marine Biology, Annamalai University, Parangipettai, 608 502, Tamil Nadu, India
- Department of Pathology and Laboratory Medicine, UBC James Hogg Research Centre, St. Paul's Hospital, Vancouver-V6Z 1Y6, British Columbia, Canada
| | - V C Renju
- Department of Medical Biochemistry, Rajah Muthiah Medical College, Annamalai University, Annamalainagar, 608 002, Tamil Nadu, India
| | - S Sethupathy
- Department of Medical Biochemistry, Rajah Muthiah Medical College, Annamalai University, Annamalainagar, 608 002, Tamil Nadu, India
| | - Somasundaram S Thirugnanasambandan
- Department of Marine Sciences, Centre of Advanced Study in Marine Biology, Annamalai University, Parangipettai, 608 502, Tamil Nadu, India
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8
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Heme-iron utilization by Leptospira interrogans requires a heme oxygenase and a plastidic-type ferredoxin-NADP+ reductase. Biochim Biophys Acta Gen Subj 2014; 1840:3208-17. [PMID: 25092651 DOI: 10.1016/j.bbagen.2014.07.021] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2014] [Revised: 07/04/2014] [Accepted: 07/28/2014] [Indexed: 11/24/2022]
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9
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Shekhawat GS, Verma K. Haem oxygenase (HO): an overlooked enzyme of plant metabolism and defence. JOURNAL OF EXPERIMENTAL BOTANY 2010; 61:2255-70. [PMID: 20378668 DOI: 10.1093/jxb/erq074] [Citation(s) in RCA: 118] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Haem oxygenase (HO) degrades free haem released from haem proteins with the generation of ferrous iron (Fe2+), biliverdin-IXalpha (BV-IXalpha), and carbon monoxide (CO). The mechanism of haem cleavage has been conserved between plants and other organisms even though the function, subcellular localization, and cofactor requirements of HO differ substantially. The crystal structure of HO1, a monomeric protein, has been extensively reported in mammals, pathogenic bacteria, and cyanobacteria, but no such reports are available for higher plant HOs except a predicted model for pea HO1. Along with haem degradation, HO performs various cellular processes including iron acquisition/mobilization, phytochrome chromophore synthesis, cell protection, and stomatal regulation. To date, four HO genes (HO1, HO2, HO3, and HO4) have been reported in plants. HO1 has been well explored in cell metabolism; however, the divergent roles of the other three HOs is less known. The transcriptional up-regulation of HO1 in plants responds to many agents, such as light, UV, iron deprivation, reactive oxygen species (ROS), abscisic acid (ABA), and haematin. Recently the HO1/CO system has gained more attention due to its physiological cytoprotective role in plants. This review focuses on the recent advances made in plant HO research involving its role in environmental stresses. Moreover, the review emphasizes physiological, biochemical, and molecular aspects of this enzyme in plants.
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Affiliation(s)
- G S Shekhawat
- Department of Bioscience and Biotechnology, Banasthali University, Banasthali-304022, Rajasthan, India.
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Okada K. HO1 and PcyA proteins involved in phycobilin biosynthesis form a 1:2 complex with ferredoxin-1 required for photosynthesis. FEBS Lett 2009; 583:1251-6. [DOI: 10.1016/j.febslet.2009.03.052] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2009] [Revised: 03/18/2009] [Accepted: 03/23/2009] [Indexed: 10/21/2022]
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Okada K. The novel heme oxygenase-like protein fromPlasmodiumfalciparumconverts heme to bilirubin IXα in the apicoplast. FEBS Lett 2008; 583:313-9. [DOI: 10.1016/j.febslet.2008.12.015] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2008] [Revised: 12/02/2008] [Accepted: 12/05/2008] [Indexed: 11/24/2022]
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12
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Dammeyer T, Frankenberg-Dinkel N. Function and distribution of bilin biosynthesis enzymes in photosynthetic organisms. Photochem Photobiol Sci 2008; 7:1121-30. [PMID: 18846276 DOI: 10.1039/b807209b] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Bilins are open-chain tetrapyrrole molecules essential for light-harvesting and/or sensing in many photosynthetic organisms. While they serve as chromophores in phytochrome-mediated light-sensing in plants, they additionally function in light-harvesting in cyanobacteria, red algae and cryptomonads. Associated to phycobiliproteins a variety of bile pigments is responsible for the specific light-absorbance properties of the organisms enabling efficient photosynthesis under different light conditions. The initial step of bilin biosynthesis is the cleavage of heme by heme oxygenases (HO) to afford the first linear molecule biliverdin. This reaction is ubiquitously found also in non-photosynthetic organisms. Biliverdin is then further reduced by site specific reductases most of them belonging to the interesting family of ferredoxin-dependent bilin reductases (FDBRs)-a new family of radical oxidoreductases. In recent years much progress has been made in the field of heme oxygenases but even more in the widespread family of FDBRs, revealing novel biochemical FDBR activities, new crystal structures and new ecological aspects, including the discovery of bilin biosynthesis genes in wild marine phage populations. The aim of this review is to summarize and discuss the recent progress in this field and to highlight the new and remaining questions.
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Affiliation(s)
- Thorben Dammeyer
- Physiology of Microorganisms, Ruhr-University Bochum, Universitaetsstr. 150, 44780 Bochum, Germany
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Beale SI. Biosynthesis of open-chain tetrapyrroles in plants, algae, and cyanobacteria. CIBA FOUNDATION SYMPOSIUM 2007; 180:156-68; discussion 168-71. [PMID: 7842851 DOI: 10.1002/9780470514535.ch9] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Phycobilins are open-chain tetrapyrroles of plants and algae which act as the chromophores of phycobiliproteins where they function as light energy-harvesting pigments. Phytochromobilin, another open-chain tetrapyrrole, is the chromophore of phytochrome, which functions as a light-sensing pigment in plant development. These open-chain tetrapyrroles are biosynthetically derived from protohaem. Enzyme reactions that convert protohaem to biliverdin IX alpha, and biliverdin IX alpha to phycocyanobilin, have been detected and characterized in extracts of the unicellular rhodophyte Cyanidium caldarium. Algal haem oxygenase and algal biliverdin-IX alpha reductase are both soluble enzymes that use electrons derived from reduced ferredoxin. Biochemical intermediates in the conversion of biliverdin IX alpha to (3E)-phycocyanobilin were identified as 15, 16-dihydrobiliverdin IX alpha, (3Z)-phycoerythrobilin and (3Z)-phycocyanobilin. Separate enzymes catalyse the two two-electron reduction steps in the conversion of biliverdin IX alpha to (3Z)-phycoerythrobilin. Z-to-E isomerization of the phycobilin ethylidine group is catalysed by an enzyme that requires glutathione for activity. Protein-bound phycoerythrobilin can be chemically converted to phytochromobilin which can then be released from the protein by methanolysis. This procedure was used to produce phytochromobilin in quantities sufficient to allow its chemical characterization and use in phytochrome reconstitution experiments. The results indicate that (2R,3E)-phytochromobilin spontaneously condenses with recombinant oat apophytochrome to form photoreversible holoprotein that is spectrally identical to native phytochrome.
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Affiliation(s)
- S I Beale
- Division of Biology and Medicine, Brown University, Providence, RI 02912
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Zhang X, Migita CT, Sato M, Sasahara M, Yoshida T. Protein expressed by the ho2 gene of the cyanobacterium Synechocystis sp. PCC 6803 is a true heme oxygenase. Properties of the heme and enzyme complex. FEBS J 2005; 272:1012-22. [PMID: 15691334 DOI: 10.1111/j.1742-4658.2004.04535.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Two isoforms of a heme oxygenase gene, ho1 and ho2, with 51% identity in amino acid sequence have been identified in the cyanobacterium Synechocystis sp. PCC 6803. Isoform-1, Syn HO-1, has been characterized, while isoform-2, Syn HO-2, has not. In this study, a full-length ho2 gene was cloned using synthetic DNA and Syn HO-2 was demonstrated to be highly expressed in Escherichia coli as a soluble, catalytically active protein. Like Syn HO-1, the purified Syn HO-2 bound hemin stoichiometrically to form a heme-enzyme complex and degraded heme to biliverdin IXalpha, CO and iron in the presence of reducing systems such as NADPH/ferredoxin reductase/ferredoxin and sodium ascorbate. The activity of Syn HO-2 was found to be comparable to that of Syn HO-1 by measuring the amount of bilirubin formed. In the reaction with hydrogen peroxide, Syn HO-2 converted heme to verdoheme. This shows that during the conversion of hemin to alpha-meso-hydroxyhemin, hydroperoxo species is the activated oxygen species as in other heme oxygenase reactions. The absorption spectrum of the hemin-Syn HO-2 complex at neutral pH showed a Soret band at 412 nm and two peaks at 540 nm and 575 nm, features observed in the hemin-Syn HO-1 complex at alkaline pH, suggesting that the major species of iron(III) heme iron at neutral pH is a hexa-coordinate low spin species. Electron paramagnetic resonance (EPR) revealed that the iron(III) complex was in dynamic equilibrium between low spin and high spin states, which might be caused by the hydrogen bonding interaction between the distal water ligand and distal helix components. These observations suggest that the structure of the heme pocket of the Syn HO-2 is different from that of Syn HO-1.
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Affiliation(s)
- Xuhong Zhang
- Department of Biochemistry, Yamagata University School of Medicine, Japan
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Sugishima M, Migita CT, Zhang X, Yoshida T, Fukuyama K. Crystal structure of heme oxygenase-1 from cyanobacterium Synechocystis sp. PCC 6803 in complex with heme. ACTA ACUST UNITED AC 2005; 271:4517-25. [PMID: 15560792 DOI: 10.1111/j.1432-1033.2004.04411.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Heme oxygenase (HO) catalyzes the oxidative degradation of heme utilizing molecular oxygen and reducing equivalents. In photosynthetic organisms, HO functions in the biosynthesis of such open-chain tetrapyrroles as phyto-chromobilin and phycobilins, which are involved in the signal transduction for light responses and light harvesting for photosynthesis, respectively. We have determined the first crystal structure of a HO-1 from a photosynthetic organism, Synechocystis sp. PCC 6803 (Syn HO-1), in complex with heme at 2.5 A resolution. Heme-Syn HO-1 shares a common folding with other heme-HOs. Although the heme pocket of heme-Syn HO-1 is, for the most part, similar to that of mammalian HO-1, they differ in such features as the flexibility of the distal helix and hydrophobicity. In addition, 2-propanol derived from the crystallization solution occupied the hydrophobic cavity, which is proposed to be a CO trapping site in rat HO-1 that suppresses product inhibition. Although Syn HO-1 and mammalian HO-1 are similar in overall structure and amino acid sequence (57% similarity vs. human HO-1), their molecular surfaces differ in charge distribution. The surfaces of the heme binding sides are both positively charged, but this patch of Syn HO-1 is narrow compared to that of mammalian HO-1. This feature is suited to the selective binding of ferredoxin, the physiological redox partner of Syn HO-1; the molecular size of ferredoxin is approximately 10 kDa whereas the size of NADPH-cytochrome P450 reductase, a reducing partner of mammalian HO-1, is approximately 77 kDa. A docking model of heme-Syn HO-1 and ferredoxin suggests indirect electron transfer from an iron-sulfur cluster in ferredoxin to the heme iron of heme-Syn HO-1.
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Affiliation(s)
- Masakazu Sugishima
- Department of Biology, Graduate School of Science, Osaka University, Toyonaka, Osaka, Japan
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Wang J, Lad L, Poulos TL, Ortiz de Montellano PR. Regiospecificity determinants of human heme oxygenase: differential NADPH- and ascorbate-dependent heme cleavage by the R183E mutant. J Biol Chem 2004; 280:2797-806. [PMID: 15525643 DOI: 10.1074/jbc.m411229200] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The ability of the human heme oxygenase-1 (hHO-1) R183E mutant to oxidize heme in reactions supported by either NADPH-cytochrome P450 reductase or ascorbic acid has been compared. The NADPH-dependent reaction, like that of wild-type hHO-1, yields exclusively biliverdin IXalpha. In contrast, the R183E mutant with ascorbic acid as the reductant produces biliverdin IXalpha (79 +/- 4%), IXdelta (19 +/- 3%), and a trace of IXbeta. In the presence of superoxide dismutase and catalase, the yield of biliverdin IXdelta is decreased to 8 +/- 1% with a corresponding increase in biliverdin IXalpha. Spectroscopic analysis of the NADPH-dependent reaction shows that the R183E ferric biliverdin complex accumulates, because reduction of the iron, which is required for sequential iron and biliverdin release, is impaired. Reversal of the charge at position 183 makes reduction of the iron more difficult. The crystal structure of the R183E mutant, determined in the ferric and ferrous-NO bound forms, shows that the heme primarily adopts the same orientation as in wild-type hHO-1. The structure of the Fe(II).NO complex suggests that an altered active site hydrogen bonding network supports catalysis in the R183E mutant. Furthermore, Arg-183 contributes to the regiospecificity of the wild-type enzyme, but its contribution is not critical. The results indicate that the ascorbate-dependent reaction is subject to a lower degree of regiochemical control than the NADPH-dependent reaction. Ascorbate may be able to reduce the R183E ferric and ferrous dioxygen complexes in active site conformations that cannot be reduced by NADPH-cytochrome P450 reductase.
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Affiliation(s)
- Jinling Wang
- Department of Pharmaceutical Chemistry, University of California, San Francisco, California 94143-2280, USA
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Migita CT, Zhang X, Yoshida T. Expression and characterization of cyanobacterium heme oxygenase, a key enzyme in the phycobilin synthesis. Properties of the heme complex of recombinant active enzyme. EUROPEAN JOURNAL OF BIOCHEMISTRY 2003; 270:687-98. [PMID: 12581208 DOI: 10.1046/j.1432-1033.2003.03421.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
An efficient bacterial expression system of cyanobacterium Synechocystis sp. PCC 6803 heme oxygenase gene, ho-1, has been constructed, using a synthetic gene. A soluble protein was expressed at high levels and was highly purified, for the first time. The protein binds equimolar free hemin to catabolize the bound hemin to ferric-biliverdin IX alpha in the presence of oxygen and reducing equivalents, showing the heme oxygenase activity. During the reaction, verdoheme intermediate is formed with the evolution of carbon monoxide. Though both ascorbate and NADPH-cytochrome P450 reductase serve as an electron donor, the heme catabolism assisted by ascorbate is considerably slow and the reaction with NADPH-cytochrome P450 reductase is greatly retarded after the oxy-heme complex formation. The optical absorption spectra of the heme-enzyme complexes are similar to those of the known heme oxygenase complexes but have some distinct features, exhibiting the Soret band slightly blue-shifted and relatively strong CT bands of the high-spin component in the ferric form spectrum. The heme-enzyme complex shows the acid-base transition, where two alkaline species are generated. EPR of the nitrosyl heme complex has established the nitrogenous proximal ligand, presumably histidine 17 and the obtained EPR parameters are discriminated from those of the rat heme oxygenase-1 complex. The spectroscopic characters as well as the catabolic activities strongly suggest that, in spite of very high conservation of the primary structure, the heme pocket structure of Synechocystis heme oxygenase isoform-1 is different from that of rat heme oxygenase isoform-1, rather resembling that of bacterial heme oxygenase, H mu O.
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Affiliation(s)
- Catharina T Migita
- Department of Biological Chemistry, Faculty of Agriculture, Yoshida, Yamaguchi University, Japan.
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Muramoto T, Tsurui N, Terry MJ, Yokota A, Kohchi T. Expression and biochemical properties of a ferredoxin-dependent heme oxygenase required for phytochrome chromophore synthesis. PLANT PHYSIOLOGY 2002; 130:1958-66. [PMID: 12481078 PMCID: PMC166706 DOI: 10.1104/pp.008128] [Citation(s) in RCA: 105] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2002] [Revised: 06/18/2002] [Accepted: 08/29/2002] [Indexed: 05/19/2023]
Abstract
The HY1 gene of Arabidopsis encodes a plastid heme oxygenase (AtHO1) required for the synthesis of the chromophore of the phytochrome family of plant photoreceptors. To determine the enzymatic properties of plant heme oxygenases, we have expressed the HY1 gene (without the plastid transit peptide) in Escherichia coli to produce an amino terminal fusion protein between AtHO1 and glutathione S-transferase. The fusion protein was soluble and expressed at high levels. Purified recombinant AtHO1, after glutathione S-transferase cleavage, is a hemoprotein that forms a 1:1 complex with heme. In the presence of reduced ferredoxin, AtHO1 catalyzed the formation of biliverdin IXalpha from heme with the concomitant production of carbon monoxide. Heme oxygenase activity could also be reconstituted using photoreduced ferredoxin generated through light irradiation of isolated thylakoid membranes, suggesting that ferredoxin may be the electron donor in vivo. In addition, AtHO1 required an iron chelator and second reductant, such as ascorbate, for full activity. These results show that the basic mechanism of heme cleavage has been conserved between plants and other organisms even though the function, subcellular localization, and cofactor requirements of heme oxygenases differ substantially.
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Affiliation(s)
- Takuya Muramoto
- Graduate School of Biological Sciences, Nara Institute of Science and Technology, Ikoma, Nara 630-0101, Japan
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20
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Zhu W, Hunt DJ, Richardson AR, Stojiljkovic I. Use of heme compounds as iron sources by pathogenic neisseriae requires the product of the hemO gene. J Bacteriol 2000; 182:439-47. [PMID: 10629191 PMCID: PMC94294 DOI: 10.1128/jb.182.2.439-447.2000] [Citation(s) in RCA: 91] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Heme compounds are an important source of iron for neisseriae. We have identified a neisserial gene, hemO, that is essential for heme, hemoglobin (Hb), and haptoglobin-Hb utilization. The hemO gene is located 178 bp upstream of the hmbR Hb receptor gene in Neisseria meningitidis isolates. The product of the hemO gene is homologous to enzymes that degrade heme; 21% of its amino acid residues are identical, and 44% are similar, to those of the human heme oxygenase-1. DNA sequences homologous to hemO were ubiquitous in commensal and pathogenic neisseriae. HemO genetic knockout strains of Neisseria gonorrhoeae and N. meningitidis were unable to use any heme source, while the assimilation of transferrin-iron and iron-citrate complexes was unaffected. A phenotypic characterization of a conditional hemO mutant, constructed by inserting an isopropyl-beta-D-thiogalactopyranoside (IPTG)-regulated promoter upstream of the ribosomal binding site of hemO, confirmed the indispensability of the HemO protein in heme utilization. The expression of HemO also protected N. meningitidis cells against heme toxicity. hemO mutants were still able to transport heme into the cell, since both heme and Hb could complement an N. meningitidis hemA hemO double mutant for growth. The expression of the HmbR receptor was reduced significantly by the inactivation of the hemO gene, suggesting that hemO and hmbR are transcriptionally linked. The expression of the unlinked Hb receptor, HpuAB, was not altered. Comparison of the polypeptide patterns of the wild type and the hemO mutant led to detection of six protein spots with an altered expression pattern, suggesting a more general role of HemO in the regulation of gene expression in Neisseriae.
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Affiliation(s)
- W Zhu
- Department of Microbiology, Emory School of Medicine, Atlanta, Georgia 30322, USA
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21
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Taketani S, Adachi Y, Kohno H, Ikehara S, Tokunaga R, Ishii T. Molecular characterization of a newly identified heme-binding protein induced during differentiation of urine erythroleukemia cells. J Biol Chem 1998; 273:31388-94. [PMID: 9813049 DOI: 10.1074/jbc.273.47.31388] [Citation(s) in RCA: 93] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
A heme-binding protein with a molecular mass of 22 kDa, termed p22 HBP, was purified from mouse liver cytosol, using blue Sepharose CL-6B. We identified a cDNA encoding p22 HBP, and sequence analysis revealed that p22 HBP comprises 190 amino acid residues (Mr 21,063) and has no homology to any other known heme-binding protein. The p22 HBP mRNA (approximately 1.0 kilobases) is ubiquitously expressed in various tissues and is extremely abundant in the liver. cDNA allows for expression of active p22 HBP, with a high affinity for 55Fe-hemin, with a Kd of 26 +/-1.8 nM. The Bmax of hemin binding to p22 HBP was 0.55 +/- 0.021 mol/mol of protein, a value consistent with one heme molecule binding per molecule of protein. The order of potency of different ligands to compete against 55Fe-hemin binding to p22 HBP was hemin = protoporphyrin IX > coproporphyrin III > bilirubin > palmitic acid > all-trans-retinoic acid. Treatment of mouse erythroleukemia (MEL) cells with dimethyl sulfoxide or hemin resulted in an increase in p22 HBP mRNA. The immunoblot analysis showed that p22 HBP increased with time in dimethyl sulfoxide- and hemin-induced MEL cells. Conversely, transfer of antisense oligonucleotides to p22 HBP cDNA resulted in a decrease of p22 HBP in dimethyl sulfoxide-treated MEL cells, and the heme content in these cells decreased to 66-71% of sense oligonucleotides-transferred cells. Thus, this newly identified heme-binding protein, p22 HBP, may be involved in heme utilization for hemoprotein synthesis and even be coupled to hemoglobin synthesis during erythroid differentiation.
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Affiliation(s)
- S Taketani
- Department of Hygiene, Kansai Medical University, Moriguchi, Osaka 570-8506, Japan.
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Cornejo J, Willows RD, Beale SI. Phytobilin biosynthesis: cloning and expression of a gene encoding soluble ferredoxin-dependent heme oxygenase from Synechocystis sp. PCC 6803. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 1998; 15:99-107. [PMID: 9744099 DOI: 10.1046/j.1365-313x.1998.00186.x] [Citation(s) in RCA: 85] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
The phytobilin chromophores of phycobiliproteins and phytochromes are biosynthesized from heme in a pathway that begins with the opening of the tetrapyrrole macrocycle of protoheme to form biliverdin IX alpha, in a reaction catalyzed by heme oxygenase. A gene containing an open reading frame with a predicted polypeptide that has a sequence similar to that of a conserved region of animal microsomal heme oxygenases was identified in the published genomic sequence of Synechocystis sp. PCC 6803. This gene, named ho1, was cloned and expressed in Escherichia coli under the control of the lacZ promoter. Cells expressing the gene became green colored due to the accumulation of biliverdin IX alpha. The size of the expressed protein was equal to the predicted size of the Synechocystis gene product, named HO1. Heme oxygenase activity was assayed in incubations containing extract of transformed E. coli cells. Incubations containing extract of induced cells, but not those containing extract of uninduced cells, had ferredoxin-dependent heme oxygenase activity. With mesoheme as the substrate, the reaction product was identified as mesobiliverdin IX alpha by spectrophotometry and reverse-phase HPLC. Heme oxygenase activity was not sedimented by centrifugation at 100, 000 g. Expression of HO1 increased several-fold during incubation of the cells for 72 h in iron-deficient medium.
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Affiliation(s)
- J Cornejo
- Division of Biology and Medicine, Brown University, Providence, Rhode Island 02912, USA
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Richaud C, Zabulon G. The heme oxygenase gene (pbsA) in the red alga Rhodella violacea is discontinuous and transcriptionally activated during iron limitation. Proc Natl Acad Sci U S A 1997; 94:11736-41. [PMID: 9326680 PMCID: PMC23621 DOI: 10.1073/pnas.94.21.11736] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/1997] [Indexed: 02/05/2023] Open
Abstract
Heme oxygenase (HO) catalyzes the opening of the heme ring with the release of iron in both plants and animals. In cyanobacteria, red algae, and cryptophyceae, HO is a key enzyme in the synthesis of the chromophoric part of the photosynthetic antennae. In an attempt to study the regulation of this key metabolic step, we cloned and sequenced the pbsA gene encoding this enzyme from the red alga Rhodella violacea. The gene is located on the chloroplast genome, split into three distant exons, and is presumably expressed by a trans-splicing mechanism. The deduced polypeptide sequence is homologous to other reported HOs from organisms containing phycobilisomes (Porphyra purpurea and Synechocystis sp. strain PCC 6803) and, to a lesser extent, to vertebrate enzymes. The expression is transcriptionally activated under iron deprivation, a stress condition frequently encountered by algae, suggesting a second role for HO as an iron-mobilizing agent in photosynthetic organisms.
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Affiliation(s)
- C Richaud
- Laboratoire de Photorégulation et Dynamique des Membranes Végétales, Centre National de la Recherche Scientifique, Unité de Recherche Associée 1810, GDR 1002, Ecole normale supérieure, 46 rue d'Ulm, 75230 Paris, France.
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Dennery PA, McDonagh AF, Spitz DR, Rodgers PA, Stevenson DK. Hyperbilirubinemia results in reduced oxidative injury in neonatal Gunn rats exposed to hyperoxia. Free Radic Biol Med 1995; 19:395-404. [PMID: 7590389 DOI: 10.1016/0891-5849(95)00032-s] [Citation(s) in RCA: 151] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Bilirubin is a potent antioxidant in vitro. To determine whether bilirubin also is an antioxidant in vivo, we studied markers of oxidative injury in the Gunn rat model exposed to hyperoxia. Homozygous jaundiced males were mated with heterozygous nonjaundiced females to obtain both jaundiced and nonjaundiced pups within a litter. Once delivered, the pups and their mother were placed in air (21% O2) or hyperoxia (> 95% O2) for 3 d. Both jaundiced and nonjaundiced pups were removed from the chambers daily. Animals were sacrificed and blood was drawn for determination of serum bilirubin, blood thiobarbituric acid-reactive substances (TBARS) by fluorescence assay, serum hydroperoxides, and serum protein oxidation. Tissues (liver, lung, and brain) were assayed for lipid peroxides (TBARS, conjugated dienes [CD], loss of polyunsaturated fatty acid content [PUFA]). We also measured a wide range of serum antioxidants including superoxide dismutase, catalase, glutathione, vitamins A, C, and E, and uric acid. Blood TBARS were significantly decreased in the jaundiced pups compared to the nonjaundiced pups on day 3 of hyperoxia, and blood TBARS were inversely correlated to serum bilirubin on day 3 of hyperoxia (R2 +/- .89). Similar decreases in serum lipid hydroperoxides and serum protein carbonyl content were detected in the jaundiced pups as compared to their nonjaundiced littermates. Other serum antioxidants were not increased in jaundiced animals compared to nonjaundiced animals. Relative lung weight was lower in jaundiced pups exposed to hyperoxia compared to similarly exposed nonjaundiced pups, suggesting a reduction in hyperoxia-induced lung edema. We detected no significant effects of bilirubin on parameters of lipid peroxidation in solid tissues. We conclude that serum bilirubin protects against serum oxidative damage in the first days of life in neonatal Gunn rats exposed to hyperoxia. We speculate that bilirubin is a functionally important transitional antioxidant in the circulation of human neonates and that it may be involved in modulation of injury due to hyperoxia.
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Affiliation(s)
- P A Dennery
- Department of Pediatrics, Stanford University School of Medicine, CA, USA
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25
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Rhie G, Beale S. Regulation of heme oxygenase activity in Cyanidium caldarium by light, glucose, and phycobilin precursors. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(17)36926-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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26
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Biosynthesis of phycobilins. Ferredoxin-supported nadph-independent heme oxygenase and phycobilin-forming activities from Cyanidium caldarium. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(18)41970-9] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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28
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Beale S, Cornejo J. Biosynthesis of phycobilins. 15,16-Dihydrobiliverdin IX alpha is a partially reduced intermediate in the formation of phycobilins from biliverdin IX alpha. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(18)54577-4] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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29
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Terry M, Lagarias J. Holophytochrome assembly. Coupled assay for phytochromobilin synthase in organello. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(18)54556-7] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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30
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Beale S, Cornejo J. Biosynthesis of phycobilins. Ferredoxin-mediated reduction of biliverdin catalyzed by extracts of Cyanidium caldarium. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(18)54575-0] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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31
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Beale S, Cornejo J. Biosynthesis of phycobilins. 3(Z)-phycoerythrobilin and 3(Z)-phycocyanobilin are intermediates in the formation of 3(E)-phycocyanobilin from biliverdin IX alpha. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(18)54576-2] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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32
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Sariaslani FS. Microbial cytochromes P-450 and xenobiotic metabolism. ADVANCES IN APPLIED MICROBIOLOGY 1991; 36:133-78. [PMID: 1877380 DOI: 10.1016/s0065-2164(08)70453-2] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- F S Sariaslani
- Central Research and Development Department, E. I. du Pont de Nemours and Company, Inc., Wilmington, Delaware 19880
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33
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Beale SI, Weinstein JD. Chapter 5 Biochemistry and regulation of photosynthetic pigment formation in plants and algae. BIOSYNTHESIS OF TETRAPYRROLES 1991. [DOI: 10.1016/s0167-7306(08)60112-x] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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34
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Brown SB, Houghton JD, Vernon DI. Biosynthesis of phycobilins. Formation of the chromophore of phytochrome, phycocyanin and phycoerythrin. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY. B, BIOLOGY 1990; 5:3-23. [PMID: 2111391 DOI: 10.1016/1011-1344(90)85002-e] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Phycobiliproteins play important roles in photomorphogenesis and photosynthesis. The light-absorbing chromophores of the phycobiliproteins are linear tetrapyrroles (bilins) very similar in structure to the mammalian bile pigments. 5-Aminolaevulinate (5-ALA) is the first committed intermediate in phycobilin synthesis. The biosynthesis of 5-ALA, destined for phycobilins, occurs via the five-carbon pathway, now well established for tetrapyrrole synthesis in plants and distinct from the mammalian pathway. The phycobilins are formed by reduction of biliverdin which results from the synthesis and degradation of haem. This haem is an essential intermediate in the biosynthesis of phycobilins. Phycocyanobilin, the blue-green pigment found in certain algae and cyanobacteria, is formed from biliverdin via phytochromobilin, the chromophore of phytochrome. This leads to the likelihood that phytochromobilin is formed as an end product, or intermediate, in the synthesis of all phycobilins.
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Affiliation(s)
- S B Brown
- Department of Biochemistry, University of Leeds, U.K
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35
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Elich TD, Lagarias JC. Formation of a Photoreversible Phycocyanobilin-Apophytochrome Adduct in vitro. J Biol Chem 1989. [DOI: 10.1016/s0021-9258(18)51573-8] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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36
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Abstract
Enzymatic systems employed by microorganisms for oxidative transformation of various organic molecules include laccases, ligninases, tyrosinases, monooxygenases, and dioxygenases. Reactions performed by these enzymes play a significant role in maintaining the global carbon cycle through either transformation or complete mineralization of organic molecules. Additionally, oxidative enzymes are instrumental in modification or degradation of the ever-increasing man-made chemicals constantly released into our environment. Due to their inherent stereo- and regioselectivity and high efficiency, oxidative enzymes have attracted attention as potential biocatalysts for various biotechnological processes. Successful commercial application of these enzymes will be possible through employing new methodologies, such as use of organic solvents in the reaction mixtures, immobilization of either the intact microorganisms or isolated enzyme preparations on various supports, and genetic engineering technology.
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Affiliation(s)
- F S Sariaslani
- Central Research and Development Department, E.I. Du Pont de Nemours and Company, Wilmington, Delaware
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