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Liu J, Knapp M, Jo M, Dill Z, Bridwell-Rabb J. Rieske Oxygenase Catalyzed C-H Bond Functionalization Reactions in Chlorophyll b Biosynthesis. ACS CENTRAL SCIENCE 2022; 8:1393-1403. [PMID: 36313167 PMCID: PMC9615114 DOI: 10.1021/acscentsci.2c00058] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Indexed: 05/03/2023]
Abstract
Rieske oxygenases perform precise C-H bond functionalization reactions in anabolic and catabolic pathways. These reactions are typically characterized as monooxygenation or dioxygenation reactions, but other divergent reactions are also catalyzed by Rieske oxygenases. Chlorophyll(ide) a oxygenase (CAO), for example is proposed to catalyze two monooxygenation reactions to transform a methyl-group into the formyl-group of Chlorophyll b. This formyl group, like the formyl groups found in other chlorophyll pigments, tunes the absorption spectra of chlorophyllb and supports the ability of several photosynthetic organisms to adapt to environmental light. Despite the importance of this reaction, CAO has never been studied in vitro with purified protein, leaving many open questions regarding whether CAO can facilitate both oxygenation reactions using just the Rieske oxygenase machinery. In this study, we demonstrated that four CAO homologues in partnership with a non-native reductase convert a Chlorophyll a precursor, chlorophyllidea, into chlorophyllideb in vitro. Analysis of this reaction confirmed the existence of the proposed intermediate, highlighted the stereospecificity of the reaction, and revealed the potential of CAO as a tool for synthesizing custom-tuned natural and unnatural chlorophyll pigments. This work thus adds to our fundamental understanding of chlorophyll biosynthesis and Rieske oxygenase chemistry.
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Braumann I, Stein N, Hansson M. Reduced chlorophyll biosynthesis in heterozygous barley magnesium chelatase mutants. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2014; 78:10-4. [PMID: 24607574 DOI: 10.1016/j.plaphy.2014.02.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2014] [Accepted: 02/05/2014] [Indexed: 05/20/2023]
Abstract
Chlorophyll biosynthesis is initiated by magnesium chelatase, an enzyme composed of three proteins, which catalyzes the insertion of Mg2+ into protoporphyrin IX to produce Mg-protoporphyrin IX. In barley (Hordeum vulgare L.) the three proteins are encoded by Xantha-f, Xantha-g and Xantha-h. Two of the gene products, XanH and XanG, belong to the structurally conserved family of AAA+ proteins (ATPases associated with various cellular activities) and form a complex involving six subunits of each protein. The complex functions as an ATP-fueled motor of the magnesium chelatase that uses XanF as substrate, which is the catalytic subunit responsible for the insertion of Mg2+ into protoporphyrin IX. Previous studies have shown that semi-dominant Xantha-h mutations result in non-functional XanH subunits that participate in the formation of inactive AAA complexes. In the present study, we identify severe mutations in the barley mutants xantha-h.38, -h.56 and -h.57. A truncated form of the protein is seen in xantha-h.38, whereas no XanH is detected in xantha-h.56 and -h.57. Heterozygous mutants show a reduction in chlorophyll content by 14-18% suggesting a slight semi-dominance of xantha-h.38, -h.56 and -h.57, which otherwise have been regarded as recessive mutations.
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Affiliation(s)
- Ilka Braumann
- Carlsberg Laboratory, Gamle Carlsberg Vej 10, 1799 Copenhagen V, Denmark
| | - Nils Stein
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), D-06466 Seeland OT Gatersleben, Germany
| | - Mats Hansson
- Carlsberg Laboratory, Gamle Carlsberg Vej 10, 1799 Copenhagen V, Denmark.
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Mueller AH, Dockter C, Gough SP, Lundqvist U, von Wettstein D, Hansson M. Characterization of mutations in barley fch2 encoding chlorophyllide a oxygenase. PLANT & CELL PHYSIOLOGY 2012; 53:1232-46. [PMID: 22537757 DOI: 10.1093/pcp/pcs062] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
The barley (Hordeum vulgare L.) mutants fch2 and clo-f2 comprise an allelic group of 14 Chl b-deficient lines. The genetic map position of fch2 corresponds to the physical map position of the gene encoding chlorophyllide a oxygenase. This enzyme converts chlorophyllide a to chlorophyllide b and it is essential for Chl b biosynthesis. The fch2 and clo-f2 barley lines were shown to be mutated in the gene for chlorophyllide a oxygenase. A five-base insertion was found in fch2 and base deletions in clo-f2.101, clo-f2.105, clo-f2.2800 and clo-f2.3613. In clo-f2.105 and clo-f2.108, nonsense base exchanges were discovered. All of these mutations led to a premature stop of translation and none of the mutants formed Chl b. The mutant clo-f2.2807 was transcript deficient and formed no Chl b. Missense mutations in clo-f2.102 (leading to the amino acid exchange D495N) and clo-f2.103 (G280D) resulted in a total lack of Chl b, whereas in the missense mutants clo-f2.107 (P419L), clo-f2.109 (A94T), clo-f2.122 (C320Y), clo-f2.123 (A94T), clo-f2.133 (A376V) and clo-f2.181 (L373F) intermediate contents of Chl b were determined. The missense mutations affect conserved residues, and their effect on chlorophyllide a oxygenase is discussed. The mutations in clo-f2.102, clo-f2.103, clo-f2.133 and clo-f2.181 may influence electron transfer as illustrated in the active site of a structural model protein. The changes in clo-f2.107, clo-f2.109, clo-f2.122 and clo-f2.123 may lead to Chlb deficiency by interfering with the regulation of chlorophyllide a oxygenase. The correlation of mutations and phenotypes strongly supports that the barley locus fch2 encodes chlorophyllide a oxygenase.
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MESH Headings
- Alleles
- Amino Acid Sequence
- Catalytic Domain
- Chlorophyll/genetics
- Chlorophyll/metabolism
- Chromosome Mapping
- Chromosomes, Plant/genetics
- Chromosomes, Plant/metabolism
- Cloning, Molecular
- Codon, Nonsense/genetics
- Codon, Nonsense/metabolism
- Electron Transport
- Frameshift Mutation
- Gene Expression Regulation, Enzymologic
- Gene Expression Regulation, Plant
- Genes, Plant
- Hordeum/enzymology
- Hordeum/genetics
- Molecular Sequence Data
- Mutation, Missense
- Oxygenases/genetics
- Oxygenases/metabolism
- Phenotype
- Plant Proteins/genetics
- Plant Proteins/metabolism
- Protein Structure, Tertiary
- Sequence Alignment
- Synteny
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Müller AH, Gough SP, Bollivar DW, Meldal M, Willows RD, Hansson M. Methods for the preparation of chlorophyllide a: an intermediate of the chlorophyll biosynthetic pathway. Anal Biochem 2011; 419:271-6. [PMID: 21925479 DOI: 10.1016/j.ab.2011.08.028] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2011] [Revised: 07/29/2011] [Accepted: 08/15/2011] [Indexed: 11/18/2022]
Abstract
Chlorophyllide a is a metabolite late in the biosynthesis of chlorophylls and bacteriochlorophylls. Isolation procedures for chlorophyllide a from Rhodobacter capsulatus CB1200 and barley (Hordeum vulgare L.) are described and compared. R. capsulatus CB1200 is a double mutant in the bacteriochlorophyllide a biosynthetic pathway, and chlorophyllide a is excreted by the cells when grown in Tween 80-containing liquid medium. It was purified by liquid or solid phase extraction, yielding 7 mg of chlorophyllide a from 1 L of culture. In a second approach, intrinsic chlorophyllase activity was used to dephytylate chlorophyll in an acetonic preparation of leaves of wild-type or chlorophyll b-deficient barley. Purification was achieved by liquid phase extraction, yielding 14 μg of chlorophyllide a per gram of barley leaves. Chlorophyllide a was identified by thin layer chromatography, absorption spectroscopy, and mass spectrometry.
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5
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Kim EH, Li XP, Razeghifard R, Anderson JM, Niyogi KK, Pogson BJ, Chow WS. The multiple roles of light-harvesting chlorophyll a/b-protein complexes define structure and optimize function of Arabidopsis chloroplasts: A study using two chlorophyll b-less mutants. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2009; 1787:973-84. [DOI: 10.1016/j.bbabio.2009.04.009] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2008] [Revised: 04/13/2009] [Accepted: 04/15/2009] [Indexed: 10/20/2022]
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6
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Pfündel EE. Deriving room temperature excitation spectra for photosystem I and photosystem II fluorescence in intact leaves from the dependence of FV/FM on excitation wavelength. PHOTOSYNTHESIS RESEARCH 2009; 100:163-177. [PMID: 19544007 DOI: 10.1007/s11120-009-9453-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2009] [Accepted: 06/01/2009] [Indexed: 05/27/2023]
Abstract
The F(0) and F(M) level fluorescence from a wild-type barley, a Chl b-less mutant barley, and a maize leaf was determined from 430 to 685 nm at 10 nm intervals using pulse amplitude-modulated (PAM) fluorimetry. Variable wavelengths of the pulsed excitation light were achieved by passing the broadband emission of a Xe flash lamp through a birefringent tunable optical filter. For the three leaf types, spectra of F(V)/F(M) (=(F(M) - F(0))/F (M)) have been derived: within each of the three spectra of F(V)/F(M), statistically meaningful variations were detected. Also, at distinct wavelength regions, the (V)/F(M) differed significantly between leaf types. From spectra of F(V)/F (M), excitation spectra of PS I and PS II fluorescence were calculated using a model that considers PS I fluorescence to be constant but variable PS II fluorescence. The photosystem spectra suggest that LHC II absorption results in high values of F(V)/F(M) between 470 and 490 nm in the two wild-type leaves but the absence of LHC II in the Chl b-less mutant barley leaf decreases the F(V)/F(M) at these wavelengths. All three leaves exhibited low values of F(V)/F(M) around 520 nm which was tentatively ascribed to light absorption by PS I-associated carotenoids. In the 550-650 nm region, the F(V)/F(M) in the maize leaf was lower than in the barley wild-type leaf which is explained with higher light absorption by PS I in maize, which is a NADP-ME C(4) species, than in barley, a C(3) species. Finally, low values of F(V)/F(M) at 685 in maize leaf and in the Chl b-less mutant barley leaf are in agreement with preferential PS I absorption at this wavelength. The potential use of spectra of the F(V)/F(M) ratio to derive information on spectral absorption properties of PS I and PS II is discussed.
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Pfündel EE, Ben Ghozlen N, Meyer S, Cerovic ZG. Investigating UV screening in leaves by two different types of portable UV fluorimeter reveals in vivo screening by anthocyanins and carotenoids. PHOTOSYNTHESIS RESEARCH 2007; 93:205-21. [PMID: 17286190 DOI: 10.1007/s11120-007-9135-7] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2006] [Accepted: 01/11/2007] [Indexed: 05/13/2023]
Abstract
Two portable instruments, designed to evaluate epidermal UV screening in leaves, were compared: the Dualex and the UV-A-PAM fluorimeter. Both instruments excite chlorophyll fluorescence at the same UV wavelengths but reference excitation is in the red and the blue spectral range in the former and the latter fluorimeter, respectively. When analyzing green leaves, general agreement of the data is obtained with the two instruments. In the presence of anthocyanins, the UV-A-PAM fluorimeter provided higher estimates for epidermal UV transmittance than the Dualex fluorimeter, which was attributed to absorption of blue excitation light by anthocyanins. By comparing data from the instruments, anthocyanin-dependent transmittance of 50% was determined in abaxial sides of some autumn leaves, and also in abaxial sides of tropical shade plants. Further, with leaves of chlorophyll b-less mutants of H. vulgare, unusually high epidermal UV transmittance was detected but this was attributed to the lack of chlorophyll b absorption and, in addition, to absorption of blue radiation by xanthophylls which are not functionally connected to photosystems.
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Goltsev V, Zaharieva I, Lambrev P, Yordanov I, Strasser R. Simultaneous analysis of prompt and delayed chlorophyll a fluorescence in leaves during the induction period of dark to light adaptation. J Theor Biol 2003; 225:171-83. [PMID: 14575651 DOI: 10.1016/s0022-5193(03)00236-4] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
An attempt is made to reveal the relation between the induction curves of delayed fluorescence (DF) registered at 0.35-5.5 ms and the prompt chlorophyll fluorescence (PF). A simple formulation was proposed to link the ratio of the transient values of delayed and variable fluorescence with the redox state of the primary electron acceptor of Photosystem II--QA, and the thylakoid membrane energization. The term luminescence potential (UL) was introduced, defined as the sum of the redox potential of QA and the transmembrane proton gradient. It was shown that UL is proportional to the ratio of DF to the variable part of PF. The theoretical model was verified and demonstrated by analysing induction courses of PF and millisecond DF, simultaneously registered from leaves of barley--wild-type and the chlorophyll b-less mutant chlorina f2. A definitive correlation between PF and DF was established. If the luminescence changes are strictly due to UL, the courses of DF and PF are reciprocal and the millisecond DF curve resembles the first derivative of the PFt function.
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Affiliation(s)
- V Goltsev
- Department of Biophysics and Radiobiology, Faculty of Biology, St. Kliment Ohridski University of Sofia, 8, Dragan Tzankov Blvd., 1164, Sofia, Bulgaria.
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9
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Pulse Amplitude Modulated Chlorophyll Fluorometry and its Application in Plant Science. LIGHT-HARVESTING ANTENNAS IN PHOTOSYNTHESIS 2003. [DOI: 10.1007/978-94-017-2087-8_13] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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10
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Dominici P, Caffarri S, Armenante F, Ceoldo S, Crimi M, Bassi R. Biochemical properties of the PsbS subunit of photosystem II either purified from chloroplast or recombinant. J Biol Chem 2002; 277:22750-8. [PMID: 11934892 DOI: 10.1074/jbc.m200604200] [Citation(s) in RCA: 103] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The biochemical properties of PsbS protein, a nuclear-encoded Photosystem II subunit involved in the high energy quenching of chlorophyll fluorescence, have been studied using preparations purified from chloroplasts or obtained by overexpression in bacteria. Despite the homology with chlorophyll a/b/xanthophyll-binding proteins of the Lhc family, native PsbS protein does not show any detectable ability to bind chlorophylls or carotenoids in conditions in which Lhc proteins maintain full pigment binding. The recombinant protein, when refolded in vitro in the presence of purified pigments, neither binds chlorophylls nor xanthophylls, differently from the homologous proteins LHCII, CP26, and CP29 that refold into stable pigment-binding complexes. Thus, it is concluded that if PsbS is a pigment-binding protein in vivo, the binding mechanism must be different from that present in other Lhc proteins. Primary sequence analysis provides evidence for homology of PsbS helices I and III with the central 2-fold symmetric core of chlorophyll a/b-binding proteins. Moreover, a structural homology owed to the presence of acidic residues in each of the two lumen-exposed loops is found with the dicyclohexylcarbodiimide/Ca(2+)-binding domain of CP29. Consistently, both native and recombinant PsbS proteins showed [(14)C]dicyclohexylcarbodiimide binding, thus supporting a functional basis for its homology with CP29 on the lumen-exposed loops. This domain is suggested to be involved in sensing low luminal pH.
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Affiliation(s)
- Paola Dominici
- Dipartimento Scientifico e Tecnologico, Università degli Studi di Verona, 37134 Verona, Italy
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11
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Gilmor AM, Itoh S. Global spectral-kinetic analysis of room temperature chlorophyll a fluorescence from light-harvesting antenna mutants of barley. Philos Trans R Soc Lond B Biol Sci 2000; 355:1371-84. [PMID: 11127992 PMCID: PMC1692871 DOI: 10.1098/rstb.2000.0699] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
This study presents a novel measurement, and simulation, of the time-resolved room temperature chlorophyll a fluorescence emission spectra from leaves of the barley wild-type and chlorophyll-b-deficient chlorina (clo) f2 and f104 mutants. The primary data were collected with a streak-camera-based picosecond-pulsed fluorometer that simultaneously records the spectral distribution and time dependence of the fluorescence decay. A new global spectral-kinetic analysis programme method, termed the double convolution integral (DCI) method, was developed to convolve the exciting laser pulse shape with a multimodal-distributed decay profile function that is again convolved with the spectral emission band amplitude functions. We report several key results obtained by the simultaneous spectral-kinetic acquisition and DCI methods. First, under conditions of dark-level fluorescence, when photosystem II (PS II) photochemistry is at a maximum at room temperature, both the clo f2 and clo f104 mutants exhibit very similar PS II spectral-decay contours as the wild-type (wt), with the main band centred around 685 nm. Second, dark-level fluorescence is strongly influenced beyond 700 nm by broad emission bands from PS I, and its associated antennae proteins, which exhibit much more rapid decay kinetics and strong integrated amplitudes. In particular a 705-720 nm band is present in all three samples, with a 710 nm band predominating in the clo f2 leaves. When the PS II photochemistry becomes inhibited, maximizing the fluorescence yield, both the clo f104 mutant and the wt exhibit lifetime increases for their major distribution modes from the minimal 205-500 ps range to the maximal 1500-2500 ps range for both the 685 nm and 740 nm bands. The clo f2 mutant, however, exhibits several unique spectral-kinetic properties, attributed to its unique PS I antennae and thylakoid structure, indicating changes in both PS II fluorescence reabsorption and PS II to PS I energy transfer pathways compared to the wt and clo f104. Photoprotective energy dissipation mediated by the xanthophyll cycle pigments and the PsbS protein was uninhibited in the clo f104 mutant but, as commonly reported in the literature, significantly inhibited in the clo f2; the inhibited energy dissipation is partly attributed to its thylakoid structure and PS II to PS I energy transfer properties. It is concluded that it is imperative with steady-state fluorometers, especially for in vivo studies of PS II efficiency or photoprotective energy dissipation, to quantify the influence of the PS I spectral emission.
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Affiliation(s)
- A M Gilmor
- Photobioenergetics Group, Research School of Biological Sciences, Australian National University, Canberra, ACT.
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12
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Horton P. Prospects for crop improvement through the genetic manipulation of photosynthesis: morphological and biochemical aspects of light capture. JOURNAL OF EXPERIMENTAL BOTANY 2000; 51 Spec No:475-485. [PMID: 10938855 DOI: 10.1093/jexbot/51.suppl_1.475] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The prospects for genetic manipulation of photosynthesis are assessed with an emphasis on the biochemical and morphological aspects of light capture. The connection between different parts of the photosynthetic process is considered together with the influence of environmental factors, development and acclimation, and metabolic regulation. The sites of real and potential photosynthetic losses are identified, using tropical rice as a case study. The important interaction between photosynthetic capacity, acclimation to the light environment, nitrogen accumulation and canopy architecture are discussed. The possibility of genetic intervention to increase both biomass accumulation and improve nitrogen economy simultaneously are considered. Finally, the numerous procedures for genetic manipulation of light harvesting are also discussed, with a view of improving radiation-use efficiency in crops.
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Affiliation(s)
- P Horton
- Robert Hill Institute for Photosynthesis Research, Department of Molecular Biology and Biotechnology, University of Sheffield, UK.
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13
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Espineda CE, Linford AS, Devine D, Brusslan JA. The AtCAO gene, encoding chlorophyll a oxygenase, is required for chlorophyll b synthesis in Arabidopsis thaliana. Proc Natl Acad Sci U S A 1999; 96:10507-11. [PMID: 10468639 PMCID: PMC17919 DOI: 10.1073/pnas.96.18.10507] [Citation(s) in RCA: 149] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Chlorophyll b is synthesized from chlorophyll a and is found in the light-harvesting complexes of prochlorophytes, green algae, and both nonvascular and vascular plants. We have used conserved motifs from the chlorophyll a oxygenase (CAO) gene from Chlamydomonas reinhardtii to isolate a homologue from Arabidopsis thaliana. This gene, AtCAO, is mutated in both leaky and null chlorina1 alleles, and DNA sequence changes cosegregate with the mutant phenotype. AtCAO mRNA levels are higher in three different mutants that have reduced levels of chlorophyll b, suggesting that plants that do not have sufficient chlorophyll b up-regulate AtCAO gene expression. Additionally, AtCAO mRNA levels decrease in plants that are grown under dim-light conditions. We have also found that the six major Lhcb proteins do not accumulate in the null ch1-3 allele.
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Affiliation(s)
- C E Espineda
- Department of Biological Sciences, California State University, 1250 Bellflower Boulevard, Long Beach, CA, 90840-3702, USA
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14
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Hansson A, Kannangara CG, von Wettstein D, Hansson M. Molecular basis for semidominance of missense mutations in the XANTHA-H (42-kDa) subunit of magnesium chelatase. Proc Natl Acad Sci U S A 1999; 96:1744-9. [PMID: 9990095 PMCID: PMC15580 DOI: 10.1073/pnas.96.4.1744] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
During biosynthesis of bacteriochlorophyll or chlorophyll, three protein subunits of 140, 70, and 42 kDa interact to insert Mg2+ into protoporphyrin IX. The semidominant Chlorina-125, -157, and -161 mutants in barley are deficient in this step and accumulate protoporphyrin IX after feeding on 5-aminolevulinate. Chlorina-125, -157, and -161 are allelic to the recessive xantha-h mutants and contain G559A, G806A, and C271T mutations, respectively. These mutations cause single amino acid substitutions in residues that are conserved in all known primary structures of the 42-kDa subunit. In vitro complementation and reconstitution of Mg-chelatase activity show that the 42-kDa subunits are defective in the semidominant Chlorina mutants. A mutated protein is maintained in the Chlorina plastids, unlike in the xantha-h plastids. Heterozygous Chlorina seedlings have 25-50% of the Mg-chelatase activity of wild-type seedlings. Codominant expression of active and inactive 42-kDa subunits in heterozygous Chlorina seedlings is likely to produce two types of heterodimers between the strongly interacting 42-kDa and 70-kDa subunits. Reduced Mg-chelatase activity is explained by the capacity of heterodimers consisting of mutated 42-kDa and wild-type 70-kDa protein to bind to the 140-kDa subunit. The 42-kDa subunit is similar to chaperones that refold denatured polypeptides with respect to its ATP-to-ADP exchange activity and its ability to generate ATPase activity with the 70-kDa subunit. We hypothesize that the association of the 42-kDa subunit with the 70-kDa subunit allows them to form a specific complex with the 140-kDa subunit and that this complex inserts Mg2+ into protoporphyrin IX.
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Affiliation(s)
- A Hansson
- Department of Biochemistry, Center for Chemistry and Chemical Engineering, Lund University, P.O. Box 124, S-221 00 Lund, Sweden
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15
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Tanaka A, Ito H, Tanaka R, Tanaka NK, Yoshida K, Okada K. Chlorophyll a oxygenase (CAO) is involved in chlorophyll b formation from chlorophyll a. Proc Natl Acad Sci U S A 1998; 95:12719-23. [PMID: 9770552 PMCID: PMC22897 DOI: 10.1073/pnas.95.21.12719] [Citation(s) in RCA: 263] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Chlorophyll b is an ubiquitous accessory pigment in land plants, green algae, and prochlorophytes. Its biosynthesis plays a key role in the adaptation to various light environments. We isolated six chlorophyll b-less mutants by insertional mutagenesis by using the nitrate reductase or argininosuccinate lyase genes as tags and examined the rearrangement of mutant genomes. We found that an overlapping region of a nuclear genome was deleted in all mutants and that this encodes a protein whose sequence is similar to those of methyl monooxygenases. This coding sequence also contains putative binding domains for a [2Fe-2S] Rieske center and for a mononuclear iron. The results demonstrate that a chlorophyll a oxygenase is involved in chlorophyll b formation. The reaction mechanism of chlorophyll b formation is discussed.
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Affiliation(s)
- A Tanaka
- The Institute of Low Temperature Science, Hokkaido University, Sapporo 0600819, Japan.
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16
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Knoetzel J, Bossmann B, Grimme LH. Chlorina and viridis mutants of barley (Hordeum vulgare L.) allow assignment of long-wavelength chlorophyll forms to individual Lhca proteins of photosystem I in vivo. FEBS Lett 1998; 436:339-42. [PMID: 9801144 DOI: 10.1016/s0014-5793(98)01158-2] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The isolated subcomplex LHCI-730 of plant photosystem I (PSI) chlorophyll (Chl) alb binding antenna is a heterodimer of Lhca1 and Lhca4 and has a 77 K fluorescence emission peak at 730 nm (F730). Recently, three Chl spectral forms with 77 K fluorescence emission peaks at 720 nm, 730 nm and 742 nm were identified in native PSI. In an attempt to assign the two longest wavelength emission maxima to peripheral PSI antenna proteins, we performed 77 K fluorescence emission spectroscopy on intact leaves of chlorina and viridis mutants from barley which lack individual LHCI-730 proteins. This approach indicates that F732 is found only in Lhca1 and F742 only in Lhca4, when these proteins are associated with the PSI reaction centre.
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Affiliation(s)
- J Knoetzel
- Institute of Cell Biology, Biochemistry and Biotechnology, University of Bremen, Germany.
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17
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Giuffra E, Cugini D, Croce R, Bassi R. Reconstitution and pigment-binding properties of recombinant CP29. EUROPEAN JOURNAL OF BIOCHEMISTRY 1996; 238:112-20. [PMID: 8665927 DOI: 10.1111/j.1432-1033.1996.0112q.x] [Citation(s) in RCA: 117] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The minor light-harvesting chlorophyll-a/b-binding protein CP29 (Lhcb4), overexpressed in Escherichia coli, has been reconstituted in vitro with pigments. The recombinant pigment-protein complexes show biochemical and spectral properties identical to the native CP29 purified from maize thylakoids. The xanthophyll lutein is the only carotenoid necessary for reconstitution, a finding consistent with the structural role of two lutein molecules/polypeptide suggested by the crystallographic data for the homologous protein light-harvesting chlorophyll-a/b-binding protein of photosystem II (LHCII). The CP29 protein scaffold can accommodate different chromophores. This conclusion was deduced by the observation that the pigment composition of the reconstituted protein depends on the pigments present in the reconstitution mixture. Thus, in addition to a recombinant CP29 identical to the native one, two additional forms of the complex could be obtained by increasing chlorophyll b content. This finding is typical of CP29 because the major LHCII complex shows an absolute selectivity for chromophore binding [Plumley, F. G. & Schmidt, G. W. (1987) Proc. Natl Acad. Sci. USA 84, 146-150; Paulsen, H., Rümler, U. & Rüdiger, W. (1990) Planta (Heidelb.) 181, 204-211], and it is consistent with the higher stability of CP29 during greening and in chlorophyll b mutants compared with LHCII.
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Affiliation(s)
- E Giuffra
- Università di Verona, Facoltà di Scienze MM. FF. NN., Italia
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Gilmore AM, Hazlett TL, Debrunner PG. Photosystem II chlorophyll a fluorescence lifetimes and intensity are independent of the antenna size differences between barley wild-type and chlorina mutants: Photochemical quenching and xanthophyll cycle-dependent nonphotochemical quenching of fluorescence. PHOTOSYNTHESIS RESEARCH 1996; 48:171-187. [PMID: 24271297 DOI: 10.1007/bf00041007] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/1995] [Accepted: 02/14/1996] [Indexed: 06/02/2023]
Abstract
Photosystem II (PS II) chlorophyll (Chl) a fluorescence lifetimes were measured in thylakoids and leaves of barley wild-type and chlorina f104 and f2 mutants to determine the effects of the PS II Chl a+b antenna size on the deexcitation of absorbed light energy. These barley chlorina mutants have drastically reduced levels of PS II light-harvesting Chls and pigment-proteins when compared to wild-type plants. However, the mutant and wild-type PS II Chl a fluorescence lifetimes and intensity parameters were remarkably similar and thus independent of the PS II light-harvesting antenna size for both maximal (at minimum Chl fluorescence level, Fo) and minimal rates of PS II photochemistry (at maximum Chl fluorescence level, Fm). Further, the fluorescence lifetimes and intensity parameters, as affected by the trans-thylakoid membrane pH gradient (ΔpH) and the carotenoid pigments of the xanthophyll cycle, were also similar and independent of the antenna size differences. In the presence of a ΔpH, the xanthophyll cycle-dependent processes increased the fractional intensity of a Chl a fluorescence lifetime distribution centered around 0.4-0.5 ns, at the expense of a 1.6 ns lifetime distribution (see Gilmore et al. (1995) Proc Natl Acad Sci USA 92: 2273-2277). When the zeaxanthin and antheraxanthin concentrations were measured relative to the number of PS II reaction center units, the ratios of fluorescence quenching to [xanthophyll] were similar between the wild-type and chlorina f104. However, the chlorina f104, compared to the wild-type, required around 2.5 times higher concentrations of these xanthophylls relative to Chl a+b to obtain the same levels of xanthophyll cycle-dependent fluorescence quenching. We thus suggest that, at a constant ΔpH, the fraction of the short lifetime distribution is determined by the concentration and thus binding frequency of the xanthophylls in the PS II inner antenna. The ΔpH also affected both the widths and centers of the lifetime distributions independent of the xanthophyll cycle. We suggest that the combined effects of the xanthophyll cycle and ΔpH cause major conformational changes in the pigment-protein complexes of the PS II inner or core antennae that switch a normal PS II unit to an increased rate constant of heat dissipation. We discuss a model of the PS II photochemical apparatus where PS II photochemistry and xanthophyll cycle-dependent energy dissipation are independent of the Peripheral antenna size.
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Affiliation(s)
- A M Gilmore
- Department of Plant Biology, University of Illinois at Urbana-Champaign, 61801-3707, Urbana, IL, USA
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Meurer J, Meierhoff K, Westhoff P. Isolation of high-chlorophyll-fluorescence mutants of Arabidopsis thaliana and their characterisation by spectroscopy, immunoblotting and northern hybridisation. PLANTA 1996; 198:385-96. [PMID: 8717135 DOI: 10.1007/bf00620055] [Citation(s) in RCA: 128] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Thirty-four recessive photosynthetic mutants of the high-chlorophyll-fluorescence (hcf) phenotype have been isolated by screening 7700 M2 progenies of ethyl methane sulfonate-treated seeds of Arabidopsis thaliana. Most of the mutants isolated were found to be seedling-lethal, but could be grown on sucrose-supplemented media. Chlorophyll (Chl) fluorescence induction, absorption changes in the reaction-centre chlorophyll of PS I (P700) at 830 nm and Chl a/Chl b ratios were recorded in order to probe the photosynthetic functions and to define the mutational lesion. These studies were complemented by immunoblot and Northern analyses which finally led to the classification of the mutants into six different groups. Four classes of mutants were affected in PS I, PS II (two different classes) or the intersystem electron-transport chain, respectively. A fifth mutant class was of pleiotropic nature and the sixth class comprised a Chl b-deficient mutant. Several of the mutants showed severe deficiencies in the levels of subunits of PS I, PS II or the cytochrome b6/f complex. Thus the mutational lesions could be located precisely. Only one mutant was defective in the transcript patterns of some plastid-encoded photosynthesis genes. Hence most of the mutants isolated appear to be affected in translational and post-translational regulatory processes of thylakoid membrane biogenesis or in structural genes encoding constituent subunits of the thylakoid protein complexes.
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Affiliation(s)
- J Meurer
- Institut für Entwicklungs- und Molekularbiologie der Pflanzen, Heinrich-Heine-Universität, Düsseldorf, Germany
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Andrews JR, Fryer MJ, Baker NR. Consequences of LHC II deficiency for photosynthetic regulation in chlorina mutants of barley. PHOTOSYNTHESIS RESEARCH 1995; 44:81-91. [PMID: 24307028 DOI: 10.1007/bf00018299] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/1994] [Accepted: 12/21/1994] [Indexed: 06/02/2023]
Abstract
The light-harvesting chlorophyll a/b proteins associated with PS II (LHC II) are often considered to have a regulatory role in photosynthesis. The photosynthetic responses of four chlorina mutants of barley, which are deficient in LHC II to varying degrees, are examined to evaluate whether LHC II plays a regulatory role in photosynthesis. The efficiencies of light use for PS I and PS II photochemistry and for CO2 assimilation in leaves of the mutants were monitored simultaneously over a wide range of photon flux densities of white light in the presence and absence of supplementary red light. It is demonstrated that the depletions of LHC II in these mutants results in a severe imbalance in the relative rates of excitation of PS I and PS II in favour of PS I, which cannot be alleviated by preferential excitation of PS II. Analyses of xanthophyll cycle pigments and fluorescence quenching in leaves of the mutants indicated that the major LHC II components are not required to facilitate the light-induced quenching associated with zeaxanthin formation. It is concluded that LHC II is important to balance the distribution of excitation energy between PS I and PS II populations over a wide range of photon flux densities. It appears that LHC II may also be important in determining the quantum efficiency of PS II photochemistry by reducing the rate of quenching of excitation energy in the PS II primary antennae.
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Affiliation(s)
- J R Andrews
- Department of Biology, University of Essex, CO4 3SQ, Colchester, UK
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Harrison MA, Nemson JA, Melis A. Assembly and composition of the chlorophyll a-b light-harvesting complex of barley (Hordeum vulgare L.): Immunochemical analysis of chlorophyll b-less and chlorophyll b-deficient mutants. PHOTOSYNTHESIS RESEARCH 1993; 38:141-51. [PMID: 24317910 DOI: 10.1007/bf00146413] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/1993] [Accepted: 08/31/1993] [Indexed: 05/09/2023]
Abstract
The chlorina-f2 mutant of barley (Hordeum vulgare L.) contains no chlorophyll b in its light-harvesting antenna, whereas the chlorina-103 mutant contains approximately 10% of the chlorophyll b found in wild-type. The absolute chlorophyll antenna size for Photosystem-II in wild-type, chlorina-103 and chlorina-f2 mutant was 250, 58 and 50 chlorophyll molecules, respectively. The absolute chlorophyll antenna size for Photosystem-I in wild-type, chlorina-103 and chlorina-f2 mutant was 210, 137 and 150 chlorophyll molecules, respoectively. In spite of the smaller PS I antenna size in the chlorina mutants, immunochemical analysis showed the presence of polypeptide components of the LHC-I auxiliary antenna with molecular masses of 25, 19.5 and 19 kDa. The chlorophyll a-b-binding LHC-II auxiliary antenna of PS II contained five polypeptide subunits in wild-type barley, termed a, b, c, d and e, with molecular masses of 30, 28, 27, 24 and 21 kDa, respectively. The polypeptide composition of the LHC-II auxiliary antenna of PS II was found to be identical in the two mutants, with only the 24 kDa subunit d present at an equal copy number per PS II in each of the mutants and in the wild-type barley. This d subunit assembles stably in the thylakoid membrane even in the absence of chlorophyll b and exhibits flexibility in its complement of bound chlorophylls. We suggest that polypeptide subunit d binds most of the chlorophyll associated with the residual PS II antenna in the chlorina mutants and that is proximal to the PS II-core complex.
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Affiliation(s)
- M A Harrison
- Department of Plant Biology, University of California, 411 Koshland Hall, 94720, Berkeley, CA, USA
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Andrews JR, Bredenkamp GJ, Baker NR. Evaluation of the role of State transitions in determining the efficiency of light utilisation for CO2 assimilation in leaves. PHOTOSYNTHESIS RESEARCH 1993; 38:15-26. [PMID: 24317826 DOI: 10.1007/bf00015057] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/1993] [Accepted: 06/14/1993] [Indexed: 05/08/2023]
Abstract
Wheat leaves were exposed to light treatments that excite preferentially Photosystem I (PS I) or Photosystem II (PS II) and induce State 1 or State 2, respectively. Simultaneous measurements of CO2 assimilation, chlorophyll fluorescence and absorbance at 820 nm were used to estimate the quantum efficiencies of CO2 assimilation and PS II and PS I photochemistry during State transitions. State transitions were found to be associated with changes in the efficiency with which an absorbed photon is transferred to an open PS II reaction centre, but did not correlate with changes in the quantum efficiencies of PS II photochemistry or CO2 assimilation. Studies of the phosphorylation status of the light harvesting chlorophyll protein complex associated with PS II (LHC II) in wheat leaves and using chlorina mutants of barley which are deficient in this complex demonstrate that the changes in the effective antennae size of Photosystem II occurring during State transitions require LHC II and correlate with the phosphorylation status of LHC II. However, such correlations were not found in maize leaves. It is concluded that State transitions in C3 leaves are associated with phosphorylation-induced modifications of the PS II antennae, but these changes do not serve to optimise the use of light absorbed by the leaf for CO2 assimilation.
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Affiliation(s)
- J R Andrews
- Department of Biology, University of Essex, CO4 3SQ, Colchester, Essex, UK
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Freeze-fracture studies on barley plastid membranes. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 1989. [DOI: 10.1016/s0005-2728(89)80215-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Høyer-Hansen G, Bassi R, Hønberg LS, Simpson DJ. Immunological characterization of chlorophyll a/b-binding proteins of barley thylakoids. PLANTA 1988; 173:12-21. [PMID: 24226173 DOI: 10.1007/bf00394481] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/1987] [Accepted: 06/19/1987] [Indexed: 06/02/2023]
Abstract
Monoclonal antibodies have been raised against the light-harvesting chlorophyll a/b-binding proteins of photosystem I (LHCI) using a photosystem (PS) I preparation (PSI-200) wild-type from barley (Hordeum vulgare L. cv. Svaløf's Bonus) as the antigen. These antibodies cross-reacted with a minor light-harvesting chlorophyll a/b-protein of PSII (Chla/b-P1=CP29), but not with the major one, LHCII (=Chla/b-P2(**)). Similarly, a monoclonal antibody to Chla/b-P1, elicited by a PSII preparation as the antigen, cross-reacted with LHCI, but not LHCII. This explains why an antigen consisting of LHCII, free of LHCI, but contaminated with Chla/b-P1, can elicit antibodies which cross-react with LHCI. Immunoblot assays showed that LHCI and Chla/b-P1 have at least two epitopes in common. Immunogold labelling of thin-sectioned wild-type thylakoids confirmed a preferential localisation of Chla/b-P1 in grana partition membranes and LHCI in stroma lamellae. The presence of LHCI was demonstrated in barley mutants lacking the PSI reaction centre (viridis-zb (63)) and chlorophyll b (chlorina-f2), and was correlated with the presence of long-wavelength (730 nm) fluorescence emission at 77 K. The mutant viridis-k (23), which has a 77 K long-wavelength fluorescence peak at 720 nm, was shown by immune-blot assay to lack LHCI, although Chla/b-P1 was present.
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Affiliation(s)
- G Høyer-Hansen
- Department of Physiology, Carlsberg Laboratory, Gamle Carlsberg Vej 10, DK-2500, Copenhagen Valby, Denmark
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White MJ, Green BR. Polypeptides belonging to each of the three major chlorophyll a + b protein complexes are present in a chlorophyll-b-less barley mutant. EUROPEAN JOURNAL OF BIOCHEMISTRY 1987; 165:531-5. [PMID: 3297692 DOI: 10.1111/j.1432-1033.1987.tb11471.x] [Citation(s) in RCA: 53] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Polypeptides of the three major chlorophyll a + b protein complexes were detected in a chlorophyll-b-less barley mutant (chlorina f2) using immunological techniques. Antibodies to CP Ia, a photosystem I complex containing both the reaction center (CP I) and the chlorophyll a + b antenna (LHCI), detected substantial amounts of LHCI polypeptides in mutant thylakoids. Some polypeptides of the two photosystem-II-associated chlorophyll a + b complexes, CP 29 and LHCII, were also detected using antibodies raised against these complexes. The CP 29 apoprotein and the minor 25-kDa polypeptide of LHCII were present in amounts that could be seen by Coomassie blue staining. In contrast, the two major polypeptides of LHCII were greatly diminished in amount, and one of them may be completely absent. These data suggest that the absence of chlorophyll b may have differing effects on the synthesis, processing or turnover of the various chlorophyll a + b binding polypeptides. They also show that these polypeptides can be inserted into thylakoids in the absence of Chl b, and that significant amounts of some of them are accumulated in the mutant thylakoids.
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Bassi R, Simpson D. Chlorophyll-protein complexes of barley photosystem I. EUROPEAN JOURNAL OF BIOCHEMISTRY 1987; 163:221-30. [PMID: 3545828 DOI: 10.1111/j.1432-1033.1987.tb10791.x] [Citation(s) in RCA: 133] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Photosystem I (PSI) preparations with a chlorophyll a/b ratio of 6.0 were isolated from barley thylakoids using two different methods. The high-molecular-mass complex (CP1a) which is resolved by non-denaturing gel electrophoresis had the same properties as a PSI preparation (PSI-200) isolated by Triton X-100 solubilisation of thylakoids followed by sucrose gradient ultracentrifugation. This material had a chlorophyll:P700 ratio of 208:1 and was composed of three different chlorophyll-protein complexes which could be separated from each other by solubilising the PSI preparation in dodecyl maltoside followed by sucrose gradient ultracentrifugation. Approximately half of the chlorophyll, including all the chlorophyll b, was located in two antenna complexes designated LHCI-680 and LHCI-730, which were identified by their characteristic low-temperature fluorescence emission spectra. The rest of the chlorophyll a was associated with the PSI reaction centre, P700 Chla-P1, which fluoresced at 720 nm. Each chlorophyll-protein complex had a unique polypeptide composition and characteristic circular dichroic and absorption spectra. The use of dodecyl maltoside instead of dodecyl sulphate resulted in a less denatured form of LHCI-680, which fluoresced at 690 nm at 77 K. One of the sucrose gradient fractions contained a complex consisting of only LHCI-730 and P700 Chla-P1 which fluoresced at 731 nm, indicating that LHCI-730 is structurally associated with P700 Chla-P1 and quenches its fluorescence. Approximately three-quarters of the light-harvesting antenna chlorophyll was in LHCI-730, but only about one-quarter of the normal complement of LHCI-730 was required to quench the reaction centre. By reducing the amount of Triton relative to the chlorophyll concentration, a PSI preparation (chlorophyll a/b ratio of 3.5) with a chlorophyll:P700 ratio of 300:1 was isolated. It contained no photosystem II, but a significant amount of LHCII which was functionally connected to the PSI reaction centre. Reconstitution studies demonstrated that excitation energy transfer from LHCII to PSI requires the presence of LHCI-680, and we propose that, in PSI, the following linear excitation energy transfer sequence occurs: LHCII----LHCI-680----LHCI-730----P700 Chla-P1.
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