DOCSLIB.ORG

Open Hui Li Thesis.Pdf

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Open Hui Li Thesis.Pdf The Pennsylvania State University The Graduate School Eberly College of Science ORGANIZATION AND FUNCTION OF CHLOROSOME PROTEINS IN THE GREEN SULFUR BACTERIUM CHLOROBIUM TEPIDUM A Thesis in Biochemistry, Microbiology and Molecular Biology by Hui Li Submitted in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy May 2006 ii The thesis of Hui Li has been reviewed and approved* by the following: Donald A. Bryant Ernest C. Pollard Professor of Biotechnology Professor of Biochemistry and Molecular Biology Thesis Advisor Chair of Committee John H. Golbeck Professor of Biochemistry and Biophysics Professor of Chemistry Teh-hui Kao Professor of Biochemistry and Molecular Biology Juliette T. J. Lecomte Associate Professor of Chemistry Robert A. Schlegel Professor of Biochemistry and Molecular Biology Head of the Department of Biochemistry and Molecular Biology * Signatures are on file in the Graduate School. iii ABSTRACT Chlorosomes are the light-harvesting antennae of the green sulfur bacteria, which usually live in extremely light-limited environments. Chlorosomes are sac-like structures with highly aggregated bacteriochlorophyll (BChl) c aggregates surrounded by a galactolipid/protein monolayer envelope. In the chlorosomes of Chlorobium tepidum, ten kinds of proteins (CsmA, CsmB, CsmC, CsmD, CsmE, CsmF, CsmH, CsmI, CsmJ, and CsmX) are located on the monolayer envelope membrane. Cross-linking experiments were performed to detect the relative locations and interactions among the chlorosome envelope proteins. The cross-linking reagent EDC (1-ethyl-3-(3- dimethylaminopropyl) carbodiimide) was used to cross-link the proteins of wild-type chlorosomes and chlorosomes from mutants lacking a single chlorosome protein, and the products were separated by SDS-PAGE and detected with antibodies against specific chlorosome proteins. CsmA forms dimers, trimers, and other multimers up to octamers, and is found in the baseplate region where it also interacts with the Fenna-Matthews-Olson (FMO) protein. The pre-CsmA, CsmB and CsmF proteins, which interact with CsmA to form heterodimers, might be located on the edge of the CsmA baseplate. CsmC forms homomultimers and it might be located on the opposite side from the baseplate facing the cytoplasm. Iron-sulfur chlorosome proteins CsmI and CsmJ form heterodimers, and both interact with CsmB. A model of the protein organization of the chlorosome membrane is proposed based on the cross-linking information. Three chlorosome proteins, CsmI, CsmJ, and CsmX, have strong sequence similarity in the amino-terminal domains to [2Fe-2S] ferredoxins of the adrenodoxin/putidaredoxin subfamily. The roles of the three iron-sulfur proteins were tested in single, double and triple knock-out mutants in all combinations. The mutant strains lacking the iron-sulfur chlorosome proteins grew at similar rates as the wild type under standard conditions. They were much more sensitive to oxygen than the wild-type cells as demonstrated by cell viability test after oxygen exposure. Fluorescence quenching and restoration experiments in chlorosomes and cells of the mutants suggest that CsmI and CsmJ are the most likely candidates for transferring electrons to and from the quencher within the chlorosome (most probably chlorobiumquinone) when the iv environmental oxygen concentration is changed. CsmX, given its low concentration (~5%) compared to CsmI and CsmJ, makes little contribution to the quenching and restoration of fluorescence. The other chlorosome proteins can be divided into three groups according to their amino acid sequence similarity: CsmA/CsmE, CsmB/CsmF and CsmC/CsmD. CsmH contains two structural domains related in sequence to CsmB/CsmF and CsmC/CsmD. The functions of the chlorosome proteins were tested in double and triple mutants lacking members of the CsmB/CsmF or CsmC/CsmD motif family. The mutants exhibited apparent growth defects under limiting light intensities and contained significantly reduced amounts of cellular BChl c and/or carotenoids as indicated by absorption spectroscopy and HPLC analyses. Chlorosomes of the mutants also contained reduced amounts of BChl c and/or carotenoids, and exhibited significant differences in chlorosome size, shape, and absorption properties. These phenotypic effects strongly suggest that chlorosome proteins play roles in pigment incorporation into the chlorosomes, and that inactivation of chlorosome proteins probably inhibits pigment biosynthesis as a feedback effect. Recombinant CsmH, which contains two structural motifs specific to chlorosome proteins, was overexpressed in E. coli and purified by affinity chromatography for X-ray crystallographic analysis. Recombinant CsmA was also overexpressed in E. coli and purified from inclusion bodies. Binding analysis were performed with recombinant CsmA and Roseobacter-extracted BChl a. Evidence for in vitro binding was obtained on the basis of shifts of the BChl a absorption maximum observed by absorption spectroscopy. v TABLE OF CONTENTS LIST OF FIGURES …………………………………………………………….. ix LIST OF TABLES ……………………………………………………………… xii LIST OF ABBREVIATIONS ………………………………………………...... xiii ACKNOWLEDGEMENTS ……………………………………………………. xv Chapter 1 Green Sulfur Bacteria and the Photosynthetic Apparatus ………. 1 1.1 Green sulfur bacteria …………………………………………………………. 2 1.1.1 Natural habitats and morphology …………………………………... 2 1.1.2 Metabolic characterization ………………………………………….3 1.1.3 Phylogeny properties ………………………………………………..4 1.1.4 Chlorobium tepidum … ……………………………………………..5 1.2 The photosynthetic apparatus of green sulfur bacteria ………………………..6 1.2.1 Pigment contents and cellular localization ………………………….6 1.2.2 The chlorosome …………………………………………………….. 8 1.2.2.1 The bacteriochlorophyll c aggregates ……………………. 8 1.2.2.2 The chlorosome proteins …………………………………. 12 1.2.3 Fenna-Matthews-Olson protein ……………………………………. 13 1.2.4 The reaction center …………………………………………………. 15 1.2.5 Energy transfer pathway and kinetics …………………………….... 17 1.2.6 Electron transfer and NAD(P)+ reduction ………………………….. 19 Chapter 2 Molecular Contacts for Chlorosome Envelope Proteins Revealed by Cross-linking Studies with Chlorosomes from Chlorobium tepidum …….. 33 2.1 Abstract ………………………………………………………………………. 34 2.2 Introduction …………………………………………………………………... 35 2.3 Materials and methods ……………………………………………………….. 38 2.3.1 Chlorobium tepidum strain and growth conditions ……………….... 38 2.3.2 Isolation of light harvesting antenna ……………………………….. 39 2.3.3 Cross-linking of chlorosome proteins …………………………….... 40 vi 2.3.4 SDS-PAGE and immunoblotting analysis …………………………. 41 2.4 Results ………………………………………………………………………... 43 2.4.1 Cross-linking of chlorosome proteins ……………………………… 43 2.4.2 Organization of CsmA ……………………………………………... 44 2.4.3 Organization of CsmC and CsmD …………………………………. 47 2.4.4 Interaction between CsmI/CsmJ and CsmB ……………………….. 48 2.4.5 Interactions for other chlorosome proteins ……………………….... 49 2.5 Discussion ……………………………………………………………………. 50 Chapter 3 [2Fe-2S] Proteins in the Chlorosome: Construction and Characterization of Mutants Lacking CsmI, CsmJ and CsmX in the Chlorosome Envelope of Chlorobium tepidum ………………………………... 70 3.1 Abstract ………………………………………………………………………. 71 3.2 Introduction …………………………………………………………………... 72 3.3 Materials and methods ……………………………………………………….. 75 3.3.1 Molecular manipulation in Escherichia coli…………………. ……... 75 3.3.2 Mutant construction and confirmation in Chlorobium tepidum …… 77 3.3.3 Chlorosome isolation and SDS-PAGE …………………………...... 79 3.3.4 Pigment and quinone analysis ……………………………………… 79 3.3.5 Fluorescence spectroscopy and cell viability test ………………….. 80 3.3.6 Reverse transcription PCR …………………………………………. 81 3.4 Results ………………………………………………………………………... 82 3.4.1 Construction and verification of mutants lacking CsmI, CsmJ and CsmX …………………………………………………………………….. 82 3.4.2 Pigment and quinone contents ……………………………………... 83 3.4.3 Fluorescence quenching and restoration …………………………… 84 3.4.4 Growth rates and viability after aerobic exposure …………………. 87 3.4.5 mRNA and protein level of CsmI and CsmJ in the csmX mutant ….. 89 3.5 Discussion ……………………………………………………………………. 90 vii Chapter 4 Chlorosome Proteins and Chlorosome Assembly: Construction and Characterization of Mutants Lacking CsmB/F or CsmC/D Motifs in the Chlorosome Envelope of Chlorobium tepidum ………………………………... 108 4.1 Abstract ………………………………………………………………………. 109 4.2 Introduction …………………………………………………………………... 111 4.3 Materials and methods ……………………………………………………….. 115 4.3.1 Plasmids construction in Escherichia coli …………………………. 115 4.3.2 Growth condition and mutant construction and confirmation in Chlorobium tepidum ………………………………………………………116 4.3.3 Chlorosome isolation ………………………………………………. 117 4.3.4 Analysis of protein contents ………………………………………... 117 4.3.5 Spectroscopy and pigment content determination ………………..... 118 4.3.6 Electron microscopy ……………………………………………….. 119 4.4 Results ………………………………………………………………………... 121 4.4.1 Construction of Chlorobium tepidum mutants ……………………... 121 4.4.2 Growth defects of the mutated cells ………………………………... 122 4.4.3 Cellular absorption profile and pigment contents ………………….. 123 4.4.4 Chlorosome isolation and protein component analysis ……………. 124 4.4.5 Absorption profile and pigment contents of the chlorosomes ……... 127 4.4.6 Electron microscopy of chlorosomes …............................................. 128 4.4.7 Chlorosome protein composition of mutants lacking the BChl c and carotenoids biosynthesis enzymes ……………………………………….. 129 4.5 Discussion ……………………………………………………………………. 131 Chapter 5 Purification
Load more

Recommended publications
  • Chromatic Acclimation and Population Dynamics of Green Sulfur Bacteria Grown with Spectrally Tailored Light
    Chromatic acclimation and population dynamics of green sulfur bacteria grown with spectrally tailored light Semion K. Saikin,a,† Yadana Khin,b Joonsuk Huh,a Moataz Hannout,c Yaya Wang,b Farrokh Zare,b Alán Aspuru-Guzik,a Joseph Kuo-Hsiang Tangb,* a Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138 USA; b School of Chemistry and Biochemistry, Clark University, Worcester, MA 01610-1477 USA, c Department of Physics, Clark University, Worcester, MA 01610-1477 USA To whom correspondence should be addressed: †E-mail: [email protected], Tel: 1-617-496-8221, Fax: 1-617-496-9411 *E-mail: [email protected],Tel: 1-614-316-7886, Fax: 1-508-793-8861 Keywords: photosynthesis, chromatic acclimation, energy transfer, light-harvesting complex, chlorosome, green sulfur bacteria Living organisms have to adjust to their surrounding in order to survive in stressful conditions. We study this mechanism in one of most primitive creatures – photosynthetic green sulfur bacteria. These bacteria absorb photons very efficiently using the chlorosome antenna complexes and perform photosynthesis in extreme low-light environments. How the chlorosomes in green sulfur bacteria are acclimated to the stressful light conditions, for instance, if the spectrum of light is not optimal for absorption, is unknown. Studying Chlorobaculum tepidum cultures with far-red to near-infrared light-emitting diodes, we found that these bacteria react to changes in energy flow by regulating the amount of light- absorbing pigments and the size of the chlorosomes. Surprisingly, our results indicate that the bacteria can survive in near-infrared lights capturing low-frequency photons by the intermediate units of the light-harvesting complex.
    [Show full text]
  • Chapter 3 the Title and Subtitle of This Chapter Convey a Dual Meaning
    3.1. Introduction Chapter 3 The title and subtitle of this chapter convey a dual meaning. At first reading, the subtitle Photosynthetic Reaction might seem to indicate that the topic of the structure, function and organization of Centers: photosynthetic reaction centers is So little time, so much to do exceedingly complex and that there is simply insufficient time or space in this brief article to cover the details. While this is John H. Golbeck certainly the case, the subtitle is Department of Biochemistry additionally meant to convey the idea that there is precious little time after the and absorption of a photon to accomplish the Molecular Biology task of preserving the energy in the form of The Pennsylvania State University stable charge separation. University Park, PA 16802 USA The difficulty is there exists a fundamental physical limitation in the amount of time available so that a photochemically induced excited state can be utilized before the energy is invariably wasted. Indeed, the entire design philosophy of biological reaction centers is centered on overcoming this physical, rather than chemical or biological, limitation. In this chapter, I will outline the problem of conserving the free energy of light-induced charge separation by focusing on the following topics: 3.2. Definition of the problem: the need to stabilize a charge-separated state. 3.3. The bacterial reaction center: how the cofactors and proteins cope with this problem in a model system. 3.4. Review of Marcus theory: what governs the rate of electron transfer in proteins? 3.5. Photosystem II: a variation on a theme of the bacterial reaction center.
    [Show full text]
  • 1 Temperature and Carbon Assimilation Regulate The
    Temperature and Carbon Assimilation Regulate the Chlorosome Biogenesis in Green Sulfur Bacteria Joseph Kuo-Hsiang Tang1,*, Semion K. Saikin2, Sai Venkatesh Pingali3, Miriam M. Enriquez4, Joonsuk Huh2, Harry A. Frank4, Volker S. Urban3, Alán Aspuru-Guzik2 1School of Chemistry and Biochemistry, Clark University, Worcester, MA 01610 USA, 2Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138 USA, 3Center for Structural Molecular Biology, Biology and Soft Matter Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 USA, 4Department of Chemistry, University of Connecticut, Storrs, CT 06269 USA Running title: Metabolic regulation of chlorosome *To whom correspondence should be addressed: Tel: 1-614-316-7886, Fax: 1-508-793-8861, E-mail: [email protected] Abstract Green photosynthetic bacteria adjust the structure and functionality of the chlorosome – the light absorbing antenna complex – in response to environmental stress factors. The chlorosome is a natural self-assembled aggregate of bacteriochlorophyll (BChl) molecules. In this study we report the regulation of the biogenesis of the Chlorobaculum tepidum chlorosome by carbon assimilation in conjunction with temperature changes. Our studies indicate that the carbon source and thermal stress culture of Cba. tepidum grows slower and incorporates less BChl c in the chlorosome. Compared with the chlorosome from other cultural conditions we investigated, the chlorosome from the carbon source and thermal stress culture displays: (a) smaller cross- sectional radius and overall size; (b) simplified BChl c homologues with smaller side chains; (c) blue-shifted Qy absorption maxima and (d) a sigmoid-shaped circular dichroism (CD) spectra. Using a theoretical model we analyze how the observed spectral modifications can be associated with structural changes of BChl aggregates inside the chlorosome.
    [Show full text]
  • Probing the Spatial Organization of Bacteriochlorophyll C by Solid
    Article pubs.acs.org/biochemistry Probing the Spatial Organization of Bacteriochlorophyll c by Solid- State Nuclear Magnetic Resonance † § ‡ § † † Shih-Chi Luo, Yadana Khin, Shing-Jong Huang, Yanshen Yang, Tsai-yi Hou, Yuan-Chung Cheng, † ∥ ∥ ∥ § Hao Ming Chen, Yi-Ying Chin, Chien-Te Chen, Hong-Ji Lin, Joseph Kuo-Hsiang Tang,*, † and Jerry Chun Chung Chan*, † ‡ Department of Chemistry and Instrumentation Center, National Taiwan University, Taipei 10617, Taiwan § Department of Chemistry and Biochemistry, Clark University, Worcester, Massachusetts 01610, United States, ∥ National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan *S Supporting Information ABSTRACT: Green sulfur bacteria, which live in extremely low-light environ- ments, use chlorosomes to harvest light. A chlorosome is the most efficient, and arguably the simplest, light-harvesting antenna complex, which contains hundreds of thousands of densely packed bacteriochlorophylls (BChls). To harvest light efficiently, BChls in a chlorosome form supramolecular aggregates; thus, it is of great interest to determine the organization of the BChls in a chlorosome. In this study, we conducted a 13C solid-state nuclear magnetic resonance and Mg K-edge X-ray absorption analysis of chlorosomes from wild-type Chlorobaculum tepidum. The X-ray absorption results indicated that the coordination number of the Mg in the chlorosome must be >4, providing evidence that electrostatic interactions formed between the Mg of a BChl and the carbonyl group or the hydroxyl group of the neighboring BChl molecule. According to the intermolecular distance constraints obtained on the basis of 13C homonuclear dipolar correlation spectroscopy, we determined that the molecular assembly of BChls is dimer-based and that the hydrogen bonds among the BChls are less extensive than commonly presumed because of the twist in the orientation of the BChl dimers.
    [Show full text]
  • The Chlorosome: a Prototype for Efficient Light Harvesting In
    View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Wageningen University & Research Publications Photosynth Res DOI 10.1007/s11120-010-9533-0 REVIEW The chlorosome: a prototype for efficient light harvesting in photosynthesis Gert T. Oostergetel • Herbert van Amerongen • Egbert J. Boekema Received: 24 November 2009 / Accepted: 16 January 2010 Ó The Author(s) 2010. This article is published with open access at Springerlink.com Abstract Three phyla of bacteria include phototrophs Introduction that contain unique antenna systems, chlorosomes, as the principal light-harvesting apparatus. Chlorosomes are the Since the earliest photosynthetic organisms developed largest known supramolecular antenna systems and contain reaction centres, additional peripheral antenna systems hundreds of thousands of BChl c/d/e molecules enclosed by have evolved for light harvesting. In these light-harvesting a single membrane leaflet and a baseplate. The BChl pig- systems, dozens, hundreds or even thousands of (bacte- ments are organized via self-assembly and do not require rio)chlorophylls can funnel their excitation energy towards proteins to provide a scaffold for efficient light harvesting. reaction centres for charge separation. The green photo- Their excitation energy flows via a small protein, CsmA synthetic bacteria are anoxygenic phototrophs that contain embedded in the baseplate to the photosynthetic reaction unique antenna complexes, known as chlorosomes (Blan- centres. Chlorosomes allow for photosynthesis at very low kenship and Matsuura 2003). A chlorosome is actually a light intensities by ultra-rapid transfer of excitations to kind of organelle. In addition to the green sulphur bacteria reaction centres and enable organisms with chlorosomes to (phylum Chlorobi), they are also present in some fila- live at extraordinarily low light intensities under which no mentous anoxygenic phototrophs of the phylum Chloroflexi other phototrophic organisms can grow.
    [Show full text]
  • Superradiance of Bacteriochlorophyll C Aggregates in Chlorosomes Of
    www.nature.com/scientificreports OPEN Superradiance of bacteriochlorophyll c aggregates in chlorosomes of green photosynthetic bacteria Tomáš Malina1, Rob Koehorst2,3, David Bína4,5, Jakub Pšenčík1* & Herbert van Amerongen2,3 Chlorosomes are the main light-harvesting complexes of green photosynthetic bacteria that are adapted to a phototrophic life at low-light conditions. They contain a large number of bacteriochlorophyll c, d, or e molecules organized in self-assembling aggregates. Tight packing of the pigments results in strong excitonic interactions between the monomers, which leads to a redshift of the absorption spectra and excitation delocalization. Due to the large amount of disorder present in chlorosomes, the extent of delocalization is limited and further decreases in time after excitation. In this work we address the question whether the excitonic interactions between the bacteriochlorophyll c molecules are strong enough to maintain some extent of delocalization even after exciton relaxation. That would manifest itself by collective spontaneous emission, so-called superradiance. We show that despite a very low fuorescence quantum yield and short excited state lifetime, both caused by the aggregation, chlorosomes indeed exhibit superradiance. The emission occurs from states delocalized over at least two molecules. In other words, the dipole strength of the emissive states is larger than for a bacteriochlorophyll c monomer. This represents an important functional mechanism increasing the probability of excitation energy transfer that is vital at low-light conditions. Similar behaviour was observed also in one type of artifcial aggregates, and this may be benefcial for their potential use in artifcial photosynthesis. Green sulfur bacteria are capable to live phototrophically at extremely low-light conditions 1,2.
    [Show full text]
  • Strong Coupling Between Chlorosomes of Photosynthetic Bacteria and a Confined Optical Cavity Mode
    ARTICLE Received 2 Jul 2014 | Accepted 14 Oct 2014 | Published 28 Nov 2014 DOI: 10.1038/ncomms6561 Strong coupling between chlorosomes of photosynthetic bacteria and a confined optical cavity mode David M. Coles1, Yanshen Yang2, Yaya Wang2, Richard T. Grant3, Robert A. Taylor4, Semion K. Saikin5,6, Ala´n Aspuru-Guzik5, David G. Lidzey3, Joseph Kuo-Hsiang Tang2 & Jason M. Smith1 Strong exciton–photon coupling is the result of a reversible exchange of energy between an excited state and a confined optical field. This results in the formation of polariton states that have energies different from the exciton and photon. We demonstrate strong exciton–photon coupling between light-harvesting complexes and a confined optical mode within a metallic optical microcavity. The energetic anti-crossing between the exciton and photon dispersions characteristic of strong coupling is observed in reflectivity and transmission with a Rabi splitting energy on the order of 150 meV, which corresponds to about 1,000 chlorosomes coherently coupled to the cavity mode. We believe that the strong coupling regime presents an opportunity to modify the energy transfer pathways within photosynthetic organisms without modification of the molecular structure. 1 Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, UK. 2 Department of Chemistry and Biochemistry, Clark University, Worcester, Massachusetts 01610-1477, USA. 3 Department of Physics & Astronomy, University of Sheffield, Hicks Building, Hounsfield Road, Sheffield S3 7RH, UK. 4 Department of Physics, University of Oxford, Parks Road, Oxford OX1 3PU, UK. 5 Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138, USA.
    [Show full text]
  • Photosynthetic Light-Harvesting (Antenna) Complexes—Structures and Functions
    molecules Review Photosynthetic Light-Harvesting (Antenna) Complexes—Structures and Functions Heiko Lokstein 1,* , Gernot Renger 2,† and Jan P. Götze 3 1 Department of Chemical Physics and Optics, Charles University, Ke Karlovu 3, 12116 Prague, Czech Republic 2 Max-Volmer-Laboratorium, Technische Universität Berlin, Straße des 17. Juni 135, D-10623 Berlin, Germany 3 Institut für Chemie und Biochemie, Freie Universität Berlin, Arnimallee 22, D-14195 Berlin, Germany; [email protected] * Correspondence: [email protected] † Sadly, Professor Dr. Gernot Renger passed away on 12 January 2013. This article is dedicated to commemorate the outstanding contributions of Gernot Renger to oxygenic photosynthesis research. Abstract: Chlorophylls and bacteriochlorophylls, together with carotenoids, serve, noncovalently bound to specific apoproteins, as principal light-harvesting and energy-transforming pigments in photosynthetic organisms. In recent years, enormous progress has been achieved in the elucidation of structures and functions of light-harvesting (antenna) complexes, photosynthetic reaction centers and even entire photosystems. It is becoming increasingly clear that light-harvesting complexes not only serve to enlarge the absorption cross sections of the respective reaction centers but are vitally important in short- and long-term adaptation of the photosynthetic apparatus and regulation of the energy-transforming processes in response to external and internal conditions. Thus, the wide variety of structural diversity in photosynthetic antenna “designs” becomes conceivable. It is, however, common for LHCs to form trimeric (or multiples thereof) structures. We propose a simple, tentative explanation of the trimer issue, based on the 2D world created by photosynthetic membrane systems. Citation: Lokstein, H.; Renger, G.; Götze, J.P.
    [Show full text]
  • Comparison of the Physical Characteristics of Chlorosomes from Three Different Phyla of Green Phototrophic Bacteria
    Biochimica et Biophysica Acta 1827 (2013) 1235–1244 Contents lists available at ScienceDirect Biochimica et Biophysica Acta journal homepage: www.elsevier.com/locate/bbabio Comparison of the physical characteristics of chlorosomes from three different phyla of green phototrophic bacteria Peter G. Adams a, Ashley J. Cadby b, Benjamin Robinson b, Yusuke Tsukatani c, Marcus Tank c, Jianzhong Wen d,e, Robert E. Blankenship d,e, Donald A. Bryant c,f, C. Neil Hunter a,⁎ a Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield S10 2TN, UK b Department of Physics and Astronomy, University of Sheffield, Sheffield S3 7RH, UK c Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA 16802, USA d Department of Biology, Washington University in St. Louis, St. Louis, MO 63130, USA e Department of Chemistry, Washington University in St. Louis, St. Louis, MO 63130, USA f Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT 59717, USA article info abstract Article history: Chlorosomes, the major antenna complexes in green sulphur bacteria, filamentous anoxygenic phototrophs, Received 9 April 2013 and phototrophic acidobacteria, are attached to the cytoplasmic side of the inner cell membrane and contain Received in revised form 5 July 2013 thousands of bacteriochlorophyll (BChl) molecules that harvest light and channel the energy to membrane- Accepted 8 July 2013 bound reaction centres. Chlorosomes from phototrophs representing three different phyla, Chloroflexus (Cfx.) Available online 16 July 2013 aurantiacus, Chlorobaculum (Cba.) tepidum and the newly discovered “Candidatus (Ca.) Chloracidobacterium (Cab.) thermophilum” were analysed using PeakForce Tapping atomic force microscopy (PFT-AFM).
    [Show full text]
  • Metabolism of Carbochidrates in the Cell of Green Photosintesis Sulfur Bacteria
    Chapter 10 Metabolism of Carbochidrates in the Cell of Green Photosintesis Sulfur Bacteria M. B. Gorishniy and S. P. Gudz Additional information is available at the end of the chapter http://dx.doi.org/10.5772/50629 1. Introduction Green bacteria - are phylogenetic isolated group photosyntetic microorganisms. The peculiarity of the structure of their cells is the presence of special vesicles - so-called chlorosom containing bacteriochlorofils and carotenoids. These microorganisms can not use water as a donor of electrons to form molecular oxygen during photosynthesis. Electrons required for reduction of assimilation CO2, green bacteria are recovered from the sulfur compounds with low redox potential. Ecological niche of green bacteria is low. Well known types of green bacteria - a common aquatic organisms that occur in anoxic, was lit areas of lakes or coastal sediments. In some ecosystems, these organisms play a key role in the transformation of sulfur compounds and carbon. They are adapted to low light intensity. Compared with other phototrophic bacteria, green bacteria can lives in the lowest layers of water in oxygen-anoxic ecosystems. Representatives of various genera and species of green bacteria differ in morphology of cells, method of movement, ability to form gas vacuoles and pigment structure of the complexes. For most other signs, including metabolism, structure photosyntetic apparats and phylogeny, these families differ significantly. Each of the two most studied families of green bacteria (Chlorobium families and Chloroflexus) has a unique way of assimilation of carbon dioxide reduction. For species of the genus Chlorobium typical revers tricarboxylic acids cycle, and for members of the genus Chloroflexus - recently described 3- hidrocsypropionatn cycle.
    [Show full text]
  • Investigation of the Bacteriochlorin Rings and Its Environment in Fenna
    Investigation of the Bacteriochlorin rings and its environment in Fenna-Matthews-Olsen antenna complex revealed by neutron and ultra-high resolution X-ray crystallography Brinda Selvaraja, Xun Lua, Matthew J. Cuneoa, Dean A.A. Mylesa a Biology and Soft Matter Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, United States Photosynthesis is initiated by the capture of a photon by a pigment in an antenna complex to form an exciton, followed by its transfer to the reaction center, where charge separation takes place. In green sulfur bacteria, Fenna-Matthews-Olson (FMO) protein functions as an energy transfer wire between chlorosome and reaction center. The efficiency of the energy transfer is mediated by the specific local environment around the pigments and their optimal geometry. To understand the efficient energy transfer designed by nature and be able to apply the knowledge to fabricating bio hybrid systems for light-harvesting, uncovering the atomic details of antenna complexes has been desirable. Here we report the neutron structure and the highest resolution X-ray structures (at cryogenic and room temperature) of FMO. We have crystallized FMO from Prosthecochloris. aestuarii in a new crystal form consisting of two FMO monomers in the asymmetric unit. Those monomers belong to two separate trimers, which show distinct occupancies for the eighth Bacteriochlorophyll (BChl). Large single crystals were obtained for room temperature neutron diffraction experiment, and an all-atom structure has been refined to 2.2 Å. The X-ray resolution has been improved to 0.99 Å for cryogenic temperature and 1.25 Å for room temperature, representing the highest resolution structures of FMO.
    [Show full text]
  • Lamellar Organization of Pigments in Chlorosomes, the Light Harvesting Complexes of Green Photosynthetic Bacteria
    View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Elsevier - Publisher Connector Biophysical Journal Volume 87 August 2004 1165–1172 1165 Lamellar Organization of Pigments in Chlorosomes, the Light Harvesting Complexes of Green Photosynthetic Bacteria J. Psˇencˇ´ık,*T.P.Ikonen,y P. Laurinma¨ki,z M. C. Merckel,§ S. J. Butcher,z R. E. Serimaa,y and R. Tumaz *Department of Chemical Physics and Optics, Faculty of Mathematics and Physics, Charles University, Prague, Czech Republic; and yDivision of X-ray Physics, Department of Physical Sciences, zInstitute of Biotechnology and Department of Biological and Environmental Science, and §Helsinki Bioenergetics Group, Institute of Biotechnology, University of Helsinki, Helsinki, Finland ABSTRACT Chlorosomes of green photosynthetic bacteria constitute the most efficient light harvesting complexes found in nature. In addition, the chlorosome is the only known photosynthetic system where the majority of pigments (BChl) is not organized in pigment-protein complexes but instead is assembled into aggregates. Because of the unusual organization, the chlorosome structure has not been resolved and only models, in which BChl pigments were organized into large rods, were proposed on the basis of freeze-fracture electron microscopy and spectroscopic constraints. We have obtained the first high- resolution images of chlorosomes from the green sulfur bacterium Chlorobium tepidum by cryoelectron microscopy. Cryoelectron microscopy images revealed dense striations ;20 A˚ apart. X-ray scattering from chlorosomes exhibited a feature with the same ;20 A˚ spacing. No evidence for the rod models was obtained. The observed spacing and tilt-series cryoelectron microscopy projections are compatible with a lamellar model, in which BChl molecules aggregate into semicrystalline lateral arrays.
    [Show full text]