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Kim Y, Alia A, Kurle-Tucholski P, Wiebeler C, Matysik J. Electronic Structures of Radical-Pair-Forming Cofactors in a Heliobacterial Reaction Center. Molecules 2024; 29:1021. [PMID: 38474533 DOI: 10.3390/molecules29051021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2024] [Revised: 02/16/2024] [Accepted: 02/22/2024] [Indexed: 03/14/2024] Open
Abstract
Photosynthetic reaction centers (RCs) are membrane proteins converting photonic excitations into electric gradients. The heliobacterial RCs (HbRCs) are assumed to be the precursors of all known RCs, making them a compelling subject for investigating structural and functional relationships. A comprehensive picture of the electronic structure of the HbRCs is still missing. In this work, the combination of selective isotope labelling of 13C and 15N nuclei and the utilization of photo-CIDNP MAS NMR (photochemically induced dynamic nuclear polarization magic-angle spinning nuclear magnetic resonance) allows for highly enhanced signals from the radical-pair-forming cofactors. The remarkable magnetic-field dependence of the solid-state photo-CIDNP effect allows for observation of positive signals of the electron donor cofactor at 4.7 T, which is interpreted in terms of a dominant contribution of the differential relaxation (DR) mechanism. Conversely, at 9.4 T, the emissive signals mainly originate from the electron acceptor, due to the strong activation of the three-spin mixing (TSM) mechanism. Consequently, we have utilized two-dimensional homonuclear photo-CIDNP MAS NMR at both 4.7 T and 9.4 T. These findings from experimental investigations are corroborated by calculations based on density functional theory (DFT). This allows us to present a comprehensive investigation of the electronic structure of the cofactors involved in electron transfer (ET).
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Affiliation(s)
- Yunmi Kim
- Institut für Analytische Chemie, Universität Leipzig, Linnéstraße 3, D-04103 Leipzig, Germany
| | - A Alia
- Leiden Institute of Chemistry, Leiden University, Einsteinweg 55, 2301 RA Leiden, The Netherlands
- Institut für Medizinische Physik und Biophysik, Universität Leipzig, Härtelstr. 16-18, D-04107 Leipzig, Germany
| | - Patrick Kurle-Tucholski
- Institut für Analytische Chemie, Universität Leipzig, Linnéstraße 3, D-04103 Leipzig, Germany
| | - Christian Wiebeler
- Institut für Analytische Chemie, Universität Leipzig, Linnéstraße 3, D-04103 Leipzig, Germany
- Institut für Physik, Universität Augsburg, Universitätsstraße 1, D-86159 Augsburg, Germany
| | - Jörg Matysik
- Institut für Analytische Chemie, Universität Leipzig, Linnéstraße 3, D-04103 Leipzig, Germany
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Brütting M, Foerster JM, Kümmel S. Understanding Primary Charge Separation in the Heliobacterial Reaction Center. J Phys Chem Lett 2023; 14:3092-3102. [PMID: 36951395 DOI: 10.1021/acs.jpclett.3c00377] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
The homodimeric reaction center of heliobacteria retains features of the ancestral reaction center and can thus provide insights into the evolution of photosynthesis. Primary charge separation is expected to proceed in a two-step mechanism along either of the two reaction center branches. We reveal the first charge-separation step from first-principles calculations based on time-dependent density functional theory with an optimally tuned range-separated hybrid and ab initio Born-Oppenheimer molecular dynamics: the electron is most likely localized on the electron transfer cofactor 3 (EC3, OH-chlorophyll a), and the hole on the adjacent EC2. Including substantial parts of the surrounding protein environment into the calculations shows that a distinct structural mechanism is decisive for the relative energetic positioning of the electronic excitations: specific charged amino acids in the vicinity of EC3 lower the energy of charge-transfer excitations and thus facilitate efficient charge separation. These results are discussed considering recent experimental insights.
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Orf GS, Gisriel CJ, Granstrom J, Baker PL, Redding KE. The PshX subunit of the photochemical reaction center from Heliobacterium modesticaldum acts as a low-energy antenna. PHOTOSYNTHESIS RESEARCH 2022; 151:11-30. [PMID: 34480322 DOI: 10.1007/s11120-021-00871-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Accepted: 08/09/2021] [Indexed: 06/13/2023]
Abstract
The anoxygenic phototrophic bacterium Heliobacterium modesticaldum contains a photochemical reaction center protein complex (called the HbRC) consisting of a homodimer of the PshA polypeptide and two copies of a newly discovered polypeptide called PshX, which is a single transmembrane helix that binds two bacteriochlorophyll g molecules. To assess the function of PshX, we produced a ∆pshX strain of Hbt. modesticaldum by leveraging the endogenous Hbt. modesticaldum Type I-A CRISPR-Cas system to aid in mutant selection. We optimized this system by separating the homologous recombination and CRISPR-based selection steps into two plasmid transformations, allowing for markerless gene replacement. Fluorescence and low-temperature absorbance of the purified HbRC from the wild-type and ∆pshX strains showed that the bacteriochlorophylls bound by PshX have the lowest site energies in the entire HbRC. This indicates that PshX acts as a low-energy antenna subunit, participating in entropy-assisted uphill energy transfer toward the P800 special bacteriochlorophyll g pair. We further discuss the role that PshX may play in stability of the HbRC, its conservation in other heliobacterial species, and the evolutionary pressure to produce and maintain single-TMH subunits in similar locations in other reaction centers.
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Affiliation(s)
- Gregory S Orf
- Center for Bioenergy and Photosynthesis, School of Molecular Sciences, Arizona State University, Tempe, AZ, 85287, USA
- Infectious Disease Research, Abbott Diagnostics Division, Abbott Park, IL, 60064, USA
| | - Christopher J Gisriel
- Center for Bioenergy and Photosynthesis, School of Molecular Sciences, Arizona State University, Tempe, AZ, 85287, USA
- Department of Chemistry, Yale University, New Haven, CT, 06520, USA
| | - Jesse Granstrom
- Center for Bioenergy and Photosynthesis, School of Molecular Sciences, Arizona State University, Tempe, AZ, 85287, USA
| | - Patricia L Baker
- Center for Bioenergy and Photosynthesis, School of Molecular Sciences, Arizona State University, Tempe, AZ, 85287, USA
| | - Kevin E Redding
- Center for Bioenergy and Photosynthesis, School of Molecular Sciences, Arizona State University, Tempe, AZ, 85287, USA.
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Leung SW, Baker PL, Redding KE. Deletion of the cytochrome bc complex from Heliobacterium modesticaldum results in viable but non-phototrophic cells. PHOTOSYNTHESIS RESEARCH 2021; 148:137-152. [PMID: 34236566 DOI: 10.1007/s11120-021-00845-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2021] [Accepted: 05/04/2021] [Indexed: 06/13/2023]
Abstract
The heliobacteria, a family of anoxygenic phototrophs, possess the simplest known photosynthetic apparatus. Although they are photoheterotrophs in the light, the heliobacteria can also grow chemotrophically via pyruvate metabolism in the dark. In the heliobacteria, the cytochrome bc complex is responsible for oxidizing menaquinol and reducing cytochrome c553 in the electron flow cycle used for phototrophy. However, there is no known electron acceptor for the mobile cytochrome c553 other than the photochemical reaction center. We have, therefore, hypothesized that the cytochrome bc complex is necessary for phototrophy, but unnecessary for chemotrophic growth in the dark. We used a two-step method for CRISPR-based genome editing in Heliobacterium modesticaldum to delete the genes encoding the four major subunits of the cytochrome bc complex. Genotypic analysis verified the deletion of the petCBDA gene cluster encoding the catalytic components of the complex. Spectroscopic studies revealed that re-reduction of cytochrome c553 after flash-induced photo-oxidation was over 100 times slower in the ∆petCBDA mutant compared to the wild-type. Steady-state levels of oxidized P800 (the primary donor of the photochemical reaction center) were much higher in the ∆petCBDA mutant at every light level, consistent with a limitation in electron flow to the reaction center. The ∆petCBDA mutant was unable to grow phototrophically on acetate plus CO2 but could grow chemotrophically on pyruvate as a carbon source similar to the wild-type strain in the dark. The mutants could be complemented by reintroduction of the petCBDA gene cluster on a plasmid expressed from the clostridial eno promoter.
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Affiliation(s)
- Sabrina W Leung
- School of Molecular Sciences, Arizona State University, 1711 S Rural Rd, Box 871604, Tempe, AZ, 85287-1604, USA
| | - Patricia L Baker
- School of Molecular Sciences, Arizona State University, 1711 S Rural Rd, Box 871604, Tempe, AZ, 85287-1604, USA
| | - Kevin E Redding
- School of Molecular Sciences, Arizona State University, 1711 S Rural Rd, Box 871604, Tempe, AZ, 85287-1604, USA.
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Kondo T, Mutoh R, Tabe H, Kurisu G, Oh-Oka H, Fujiyoshi S, Matsushita M. Cryogenic Single-Molecule Spectroscopy of the Primary Electron Acceptor in the Photosynthetic Reaction Center. J Phys Chem Lett 2020; 11:3980-3986. [PMID: 32352789 DOI: 10.1021/acs.jpclett.0c00891] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The photosynthetic reaction center (RC) converts light energy into electrochemical energy. The RC of heliobacteria (hRC) is a primitive homodimeric RC containing 58 bacteriochlorophylls and 2 chlorophyll as. The chlorophyll serves as the primary electron acceptor (Chl a-A0) responsible for light harvesting and charge separation. The single-molecule spectroscopy of Chl a-A0 can be used to investigate heterogeneities of the RC photochemical function, though the low fluorescence quantum yield (0.1%) makes it difficult. Here, we show the fluorescence excitation spectroscopy of individual Chl a-A0s in single hRCs at 6 K. The fluorescence quantum yield and absorption cross section of Chl a-A0 increase 2- and 4-fold, respectively, compared to those at room temperature. The two Chl a-A0s in single hRCs are identified as two distinct peaks in the fluorescence excitation spectrum, exhibiting different excitation polarization dependences. The spectral changes caused by photobleaching indicate the energy transfer across subunits in the hRC.
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Affiliation(s)
- Toru Kondo
- Department of Physics, Graduate School of Science and Engineering, Tokyo Institute of Technology, Meguro, Tokyo 152-8551, Japan
| | - Risa Mutoh
- Institute for Protein Research, Osaka University, Suita, Osaka 565-0871, Japan
| | - Hiroaki Tabe
- Department of Physics, Graduate School of Science and Engineering, Tokyo Institute of Technology, Meguro, Tokyo 152-8551, Japan
| | - Genji Kurisu
- Institute for Protein Research, Osaka University, Suita, Osaka 565-0871, Japan
| | - Hirozo Oh-Oka
- Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan
| | - Satoru Fujiyoshi
- Department of Physics, Graduate School of Science and Engineering, Tokyo Institute of Technology, Meguro, Tokyo 152-8551, Japan
| | - Michio Matsushita
- Department of Physics, Graduate School of Science and Engineering, Tokyo Institute of Technology, Meguro, Tokyo 152-8551, Japan
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6
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Johnson WA, Redding KE. Reconstitution of the heliobacterial photochemical reaction center and cytochrome c 553 into a proteoliposome system. PHOTOSYNTHESIS RESEARCH 2020; 143:241-250. [PMID: 31838634 DOI: 10.1007/s11120-019-00695-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2019] [Accepted: 11/22/2019] [Indexed: 06/10/2023]
Abstract
The heliobacterial reaction center (HbRC) is the simplest known photochemical reaction center, in terms of its polypeptide composition. In the heliobacterial cells, its electron donor is a cytochrome (cyt) c553 attached to the membrane via a covalent linkage with a diacylglycerol. We have reconstituted purified HbRC into liposomes mimicking the phospholipid composition of heliobacterial membranes. We also incorporated a lipid with a headgroup containing Ni(II):nitrilotriacetate (NTA) to provide a binding site for the soluble version of the heliobacterial cyt c553 in which the N-terminal membrane attachment site is replaced by a hexahistidine tag. The HbRC was inserted into the liposomes with the donor side preferentially exposed to the exterior; this bias increased to nearly 100% with higher concentrations (≥ 10 mol%) of the Ni(II)-NTA lipid in the membrane, and is most likely due to the net negative charge of the surface of the membrane. The HbRC in proteoliposomes without the Ni(II)-NTA lipid exhibited normal charge separation and subsequent charge recombination of the P800+FX- state in 15 ms; however, the oxidized primary donor (P800+) was not significantly reduced by added H6-cyt c553. In contrast, with proteoliposomes containing the Ni(II)-NTA lipid, addition of H6-cyt c553 resulted in a new kinetic component resulting from fast reduction (2-5 ms) of P800+ by H6-cyt c553. The contribution of this kinetic component varied with the concentration of added H6-cyt c553 and could represent 80% or more of the total P800+ decay. Thus, the HbRC and its interaction with its native electron donor have been reconstituted into an artificial membrane system.
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Affiliation(s)
- William A Johnson
- School of Molecular Sciences, Arizona State University, 1711 S Rural Rd, Box 871604, Tempe, AZ, 85287-1604, USA
| | - Kevin E Redding
- School of Molecular Sciences, Arizona State University, 1711 S Rural Rd, Box 871604, Tempe, AZ, 85287-1604, USA.
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7
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Orf GS, Redding KE. Expression and purification of affinity-tagged variants of the photochemical reaction center from Heliobacterium modesticaldum. PHOTOSYNTHESIS RESEARCH 2019; 142:335-348. [PMID: 31542861 DOI: 10.1007/s11120-019-00672-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2019] [Accepted: 09/05/2019] [Indexed: 06/10/2023]
Abstract
The heliobacterial photochemical reaction center (HbRC) from the chlorophototrophic Firmicutes bacterium Heliobacterium modesticaldum is the only homodimeric type I RC whose structure is known. Using genetic techniques recently established in our lab, we have developed a rapid heterologous expression system for the HbRC core polypeptide PshA. Our system relies on rescue of the non-chlorophototrophic ∆pshA::cbp2p-aph3 strain of Hbt. modesticaldum by expression of a heterologous pshA gene from a replicating shuttle vector. In addition, we constructed two tagged variants of PshA, one with an N-terminal octahistidine tag and one with an internal hexahistidine tag, which facilitate rapid purification of pure, active HbRC cores in milligram quantities. We constructed a suite of shuttle vectors bearing untagged or tagged versions of pshA driven by various promoters. Surprisingly, we found that the eno and gapDH_2 promoters from Clostridium thermocellum drive better expression of pshA than fragments of DNA derived from the region upstream of the pshA locus on the Hbt. modesticaldum genome. This "pshA rescue" strategy also provided a useful window into how Hbt. modesticaldum regulates pigment synthesis and growth rate when chlorophototrophic output decreases.
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Affiliation(s)
- Gregory S Orf
- School of Molecular Sciences, Arizona State University, Tempe, AZ, 85287, USA
- Center for Bioenergy and Photosynthesis, Arizona State University, Tempe, AZ, 85287, USA
| | - Kevin E Redding
- School of Molecular Sciences, Arizona State University, Tempe, AZ, 85287, USA.
- Center for Bioenergy and Photosynthesis, Arizona State University, Tempe, AZ, 85287, USA.
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8
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Baker PL, Orf GS, Kevershan K, Pyne ME, Bicer T, Redding KE. Using the Endogenous CRISPR-Cas System of Heliobacterium modesticaldum To Delete the Photochemical Reaction Center Core Subunit Gene. Appl Environ Microbiol 2019; 85:e01644-19. [PMID: 31540988 PMCID: PMC6856316 DOI: 10.1128/aem.01644-19] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2019] [Accepted: 09/14/2019] [Indexed: 11/20/2022] Open
Abstract
In Heliobacterium modesticaldum, as in many Firmicutes, deleting genes by homologous recombination using standard techniques has been extremely difficult. The cells tend to integrate the introduced plasmid into the chromosome by a single recombination event rather than perform the double recombination required to replace the targeted locus. Transformation with a vector containing only a homologous recombination template for replacement of the photochemical reaction center gene pshA produced colonies with multiple genotypes, rather than a clean gene replacement. To address this issue, we required an additional means of selection to force a clean gene replacement. In this study, we report the genetic structure of the type I-A and I-E CRISPR-Cas systems from H. modesticaldum, as well as methods to leverage the type I-A system for genome editing. In silico analysis of the CRISPR spacers revealed a potential consensus protospacer adjacent motif (PAM) required for Cas3 recognition, which was then tested using an in vivo interference assay. Introduction of a homologous recombination plasmid that carried a miniature CRISPR array targeting sequences in pshA (downstream of a naturally occurring PAM sequence) produced nonphototrophic transformants with clean replacements of the pshA gene with ∼80% efficiency. Mutants were confirmed by PCR, sequencing, optical spectroscopy, and growth characteristics. This methodology should be applicable to any genetic locus in the H. modesticaldum genome.IMPORTANCE The heliobacteria are the only phototrophic members of the largely Gram-positive phylum Firmicutes, which contains medically and industrially important members, such as Clostridium difficile and Clostridium acetobutylicum Heliobacteria are of interest in the study of photosynthesis because their photosynthetic system is unique and the simplest known. Since their discovery in the early 1980s, work on the heliobacteria has been hindered by the lack of a genetic transformation system. The problem of introducing foreign DNA into these bacteria has been recently rectified by our group; however, issues still remained for efficient genome editing. The significance of this work is that we have characterized the endogenous type I CRISPR-Cas system in the heliobacteria and leveraged it to assist in genome editing. Using the CRISPR-Cas system allowed us to isolate transformants with precise replacement of the pshA gene encoding the main subunit of the photochemical reaction center.
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Affiliation(s)
- Patricia L Baker
- School of Molecular Sciences, Arizona State University, Tempe, Arizona, USA
- Center for Bioenergy and Photosynthesis, Arizona State University, Tempe, Arizona, USA
| | - Gregory S Orf
- School of Molecular Sciences, Arizona State University, Tempe, Arizona, USA
- Center for Bioenergy and Photosynthesis, Arizona State University, Tempe, Arizona, USA
| | - Kimberly Kevershan
- School of Molecular Sciences, Arizona State University, Tempe, Arizona, USA
| | - Michael E Pyne
- Department of Biology, Centre for Applied Synthetic Biology, Concordia University, Montréal, Québec, Canada
| | - Taner Bicer
- School of Molecular Sciences, Arizona State University, Tempe, Arizona, USA
| | - Kevin E Redding
- School of Molecular Sciences, Arizona State University, Tempe, Arizona, USA
- Center for Bioenergy and Photosynthesis, Arizona State University, Tempe, Arizona, USA
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Cardona T, Rutherford AW. Evolution of Photochemical Reaction Centres: More Twists? TRENDS IN PLANT SCIENCE 2019; 24:1008-1021. [PMID: 31351761 DOI: 10.1016/j.tplants.2019.06.016] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Revised: 06/21/2019] [Accepted: 06/28/2019] [Indexed: 05/27/2023]
Abstract
One of the earliest events in the molecular evolution of photosynthesis is the structural and functional specialisation of type I (ferredoxin-reducing) and type II (quinone-reducing) reaction centres. In this opinion article we point out that the homodimeric type I reaction centre of heliobacteria has a calcium-binding site with striking structural similarities to the Mn4CaO5 cluster of photosystem II. These similarities indicate that most of the structural elements required to evolve water oxidation chemistry were present in the earliest reaction centres. We suggest that the divergence of type I and type II reaction centres was made possible by a drastic structural shift linked to a change in redox properties that coincided with or facilitated the origin of photosynthetic water oxidation.
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Affiliation(s)
- Tanai Cardona
- Imperial College London, Department of Life Sciences, London, UK. @imperial.ac.uk
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10
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Kimura A, Itoh S. Theoretical Model of Exciton States and Ultrafast Energy Transfer in Heliobacterial Type I Homodimeric Reaction Center. J Phys Chem B 2018; 122:11852-11859. [DOI: 10.1021/acs.jpcb.8b08014] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Affiliation(s)
- Akihiro Kimura
- Department of Physics, Graduate School of Science, Nagoya University, Nagoya 464-8602, Japan
| | - Shigeru Itoh
- Department of Physics, Graduate School of Science, Nagoya University, Nagoya 464-8602, Japan
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Orf GS, Gisriel C, Redding KE. Evolution of photosynthetic reaction centers: insights from the structure of the heliobacterial reaction center. PHOTOSYNTHESIS RESEARCH 2018; 138:11-37. [PMID: 29603081 DOI: 10.1007/s11120-018-0503-2] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2018] [Accepted: 03/22/2018] [Indexed: 05/24/2023]
Abstract
The proliferation of phototrophy within early-branching prokaryotes represented a significant step forward in metabolic evolution. All available evidence supports the hypothesis that the photosynthetic reaction center (RC)-the pigment-protein complex in which electromagnetic energy (i.e., photons of visible or near-infrared light) is converted to chemical energy usable by an organism-arose once in Earth's history. This event took place over 3 billion years ago and the basic architecture of the RC has diversified into the distinct versions that now exist. Using our recent 2.2-Å X-ray crystal structure of the homodimeric photosynthetic RC from heliobacteria, we have performed a robust comparison of all known RC types with available structural data. These comparisons have allowed us to generate hypotheses about structural and functional aspects of the common ancestors of extant RCs and to expand upon existing evolutionary schemes. Since the heliobacterial RC is homodimeric and loosely binds (and reduces) quinones, we support the view that it retains more ancestral features than its homologs from other groups. In the evolutionary scenario we propose, the ancestral RC predating the division between Type I and Type II RCs was homodimeric, loosely bound two mobile quinones, and performed an inefficient disproportionation reaction to reduce quinone to quinol. The changes leading to the diversification into Type I and Type II RCs were separate responses to the need to optimize this reaction: the Type I lineage added a [4Fe-4S] cluster to facilitate double reduction of a quinone, while the Type II lineage heterodimerized and specialized the two cofactor branches, fixing the quinone in the QA site. After the Type I/II split, an ancestor to photosystem I fixed its quinone sites and then heterodimerized to bind PsaC as a new subunit, as responses to rising O2 after the appearance of the oxygen-evolving complex in an ancestor of photosystem II. These pivotal events thus gave rise to the diversity that we observe today.
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Affiliation(s)
- Gregory S Orf
- School of Molecular Sciences, Arizona State University, Tempe, AZ, 85287, USA
- Center for Bioenergy and Photosynthesis, Arizona State University, Tempe, AZ, 85287, USA
| | - Christopher Gisriel
- School of Molecular Sciences, Arizona State University, Tempe, AZ, 85287, USA
- Center for Bioenergy and Photosynthesis, Arizona State University, Tempe, AZ, 85287, USA
- The Biodesign Center for Applied Structural Discovery, Arizona State University, Tempe, AZ, 85287, USA
| | - Kevin E Redding
- School of Molecular Sciences, Arizona State University, Tempe, AZ, 85287, USA.
- Center for Bioenergy and Photosynthesis, Arizona State University, Tempe, AZ, 85287, USA.
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12
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Ortega-Ramos M, Canniffe DP, Radle MI, Neil Hunter C, Bryant DA, Golbeck JH. Engineered biosynthesis of bacteriochlorophyll g F in Rhodobacter sphaeroides. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2018; 1859:501-509. [PMID: 29496394 DOI: 10.1016/j.bbabio.2018.02.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2017] [Revised: 02/01/2018] [Accepted: 02/23/2018] [Indexed: 01/29/2023]
Abstract
Engineering photosynthetic bacteria to utilize a heterologous reaction center that contains a different (bacterio) chlorophyll could improve solar energy conversion efficiency by allowing cells to absorb a broader range of the solar spectrum. One promising candidate is the homodimeric type I reaction center from Heliobacterium modesticaldum. It is the simplest known reaction center and uses bacteriochlorophyll (BChl) g, which absorbs in the near-infrared region of the spectrum. Like the more common BChls a and b, BChl g is a true bacteriochlorin. It carries characteristic C3-vinyl and C8-ethylidene groups, the latter shared with BChl b. The purple phototrophic bacterium Rhodobacter (Rba.) sphaeroides was chosen as the platform into which the engineered production of BChl gF, where F is farnesyl, was attempted. Using a strain of Rba. sphaeroides that produces BChl bP, where P is phytyl, rather than the native BChl aP, we deleted bchF, a gene that encodes an enzyme responsible for the hydration of the C3-vinyl group of a precursor of BChls. This led to the production of BChl gP. Next, the crtE gene was deleted, thereby producing BChl g carrying a THF (tetrahydrofarnesol) moiety. Additionally, the bchGRs gene from Rba. sphaeroides was replaced with bchGHm from Hba. modesticaldum. To prevent reduction of the tail, bchP was deleted, which yielded BChl gF. The construction of a strain producing BChl gF validates the biosynthetic pathway established for its synthesis and satisfies a precondition for assembling the simplest reaction center in a heterologous organism, namely the biosynthesis of its native pigment, BChl gF.
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Affiliation(s)
- Marcia Ortega-Ramos
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, USA
| | - Daniel P Canniffe
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, USA
| | - Matthew I Radle
- Department of Chemistry, The Pennsylvania State University, University Park, PA, USA
| | - C Neil Hunter
- Department of Molecular Biology and Biotechnology, University of Sheffield, UK
| | - Donald A Bryant
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, USA; Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT, USA
| | - John H Golbeck
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, USA; Department of Chemistry, The Pennsylvania State University, University Park, PA, USA.
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13
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Kondo T, Matsuoka M, Azai C, Kobayashi M, Itoh S, Oh-oka H. Light-Induced Electron Spin-Polarized (ESP) EPR Signal of the P800+ Menaquinone– Radical Pair State in Oriented Membranes of Heliobacterium modesticaldum: Role/Location of Menaquinone in the Homodimeric Type I Reaction Center. J Phys Chem B 2018; 122:2536-2543. [DOI: 10.1021/acs.jpcb.7b12171] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Toru Kondo
- Division of Material Science (Physics), Graduate School of Science, Nagoya University, Furocho, Chikusa, Nagoya 464-8602, Japan
| | - Masahiro Matsuoka
- Department of Biological Sciences, Graduate School of Science, Osaka University, Osaka 560-0043, Japan
| | - Chihiro Azai
- Department of Biological Sciences, Graduate School of Science, Osaka University, Osaka 560-0043, Japan
| | - Masami Kobayashi
- Division of Materials Science, University of Tsukuba, Tsukuba, Ibaraki 305-8573, Japan
| | - Shigeru Itoh
- Division of Material Science (Physics), Graduate School of Science, Nagoya University, Furocho, Chikusa, Nagoya 464-8602, Japan
| | - Hirozo Oh-oka
- Department of Biological Sciences, Graduate School of Science, Osaka University, Osaka 560-0043, Japan
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14
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Dibrova DV, Shalaeva DN, Galperin MY, Mulkidjanian AY. Emergence of cytochrome bc complexes in the context of photosynthesis. PHYSIOLOGIA PLANTARUM 2017; 161:150-170. [PMID: 28493482 PMCID: PMC5600118 DOI: 10.1111/ppl.12586] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2017] [Revised: 04/22/2017] [Accepted: 05/04/2017] [Indexed: 05/18/2023]
Abstract
The cytochrome bc (cyt bc) complexes are involved in Q-cycling; they oxidize membrane quinols by high-potential electron acceptors, such as cytochromes or plastocyanin, and generate transmembrane proton gradient. In several prokaryotic lineages, and also in plant chloroplasts, the catalytic core of the cyt bc complexes is built of a four-helical cytochrome b (cyt b) that contains three hemes, a three-helical subunit IV, and an iron-sulfur Rieske protein (cytochrome b6 f-type complexes). In other prokaryotic lineages, and also in mitochondria, the cyt b subunit is fused with subunit IV, yielding a seven- or eight-helical cyt b with only two hemes (cyt bc1 -type complexes). Here we present an updated phylogenomic analysis of the cyt b subunits of cyt bc complexes. This analysis provides further support to our earlier suggestion that (1) the ancestral version of cyt bc complex contained a small four-helical cyt b with three hemes similar to the plant cytochrome b6 and (2) independent fusion events led to the formation of large cyts b in several lineages. In the search for a primordial function for the ancestral cyt bc complex, we address the intimate connection between the cyt bc complexes and photosynthesis. Indeed, the Q-cycle turnover in the cyt bc complexes demands high-potential electron acceptors. Before the Great Oxygenation Event, the biosphere had been highly reduced, so high-potential electron acceptors could only be generated upon light-driven charge separation. It appears that an ancestral cyt bc complex capable of Q-cycling has emerged in conjunction with the (bacterio)chlorophyll-based photosynthetic systems that continuously generated electron vacancies at the oxidized (bacterio)chlorophyll molecules.
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Affiliation(s)
- Daria V. Dibrova
- A.N. Belozersky Institute of Physico‐Chemical BiologyLomonosov Moscow State UniversityMoscow119991Russia
| | - Daria N. Shalaeva
- School of Bioengineering and BioinformaticsLomonosov Moscow State UniversityMoscow119991Russia
- School of PhysicsUniversity of OsnabrueckOsnabrueckD‐49069Germany
| | - Michael Y. Galperin
- National Center for Biotechnology Information, National Library of MedicineNational Institutes of HealthBethesdaMD20894USA
| | - Armen Y. Mulkidjanian
- A.N. Belozersky Institute of Physico‐Chemical BiologyLomonosov Moscow State UniversityMoscow119991Russia
- School of Bioengineering and BioinformaticsLomonosov Moscow State UniversityMoscow119991Russia
- School of PhysicsUniversity of OsnabrueckOsnabrueckD‐49069Germany
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15
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Gisriel C, Sarrou I, Ferlez B, Golbeck JH, Redding KE, Fromme R. Structure of a symmetric photosynthetic reaction center-photosystem. Science 2017; 357:1021-1025. [PMID: 28751471 DOI: 10.1126/science.aan5611] [Citation(s) in RCA: 95] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2017] [Accepted: 07/19/2017] [Indexed: 11/02/2022]
Abstract
Reaction centers are pigment-protein complexes that drive photosynthesis by converting light into chemical energy. It is believed that they arose once from a homodimeric protein. The symmetry of a homodimer is broken in heterodimeric reaction-center structures, such as those reported previously. The 2.2-angstrom resolution x-ray structure of the homodimeric reaction center-photosystem from the phototroph Heliobacterium modesticaldum exhibits perfect C2 symmetry. The core polypeptide dimer and two small subunits coordinate 54 bacteriochlorophylls and 2 carotenoids that capture and transfer energy to the electron transfer chain at the center, which performs charge separation and consists of 6 (bacterio)chlorophylls and an iron-sulfur cluster; unlike other reaction centers, it lacks a bound quinone. This structure preserves characteristics of the ancestral reaction center, providing insight into the evolution of photosynthesis.
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Affiliation(s)
- Christopher Gisriel
- School of Molecular Sciences, Arizona State University, Tempe, AZ 85287, USA
| | - Iosifina Sarrou
- Center for Free-Electron Laser Science, Deutsches Elektronen-Synchrotron (DESY), 22607 Hamburg, Germany
| | - Bryan Ferlez
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA 16802, USA
| | - John H Golbeck
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA 16802, USA.,Department of Chemistry, The Pennsylvania State University, University Park, PA 16802, USA
| | - Kevin E Redding
- School of Molecular Sciences, Arizona State University, Tempe, AZ 85287, USA.,Center for Bioenergy and Photosynthesis, Arizona State University, Tempe, AZ 85287, USA
| | - Raimund Fromme
- School of Molecular Sciences, Arizona State University, Tempe, AZ 85287, USA. .,Center of Applied Structural Discovery, Biodesign Institute, Tempe, AZ 85287, USA
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16
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Ferlez B, Agostini A, Carbonera D, Golbeck JH, van der Est A. Triplet Charge Recombination in Heliobacterial Reaction Centers Does Not Produce a Spin-Polarized EPR Spectrum. Z PHYS CHEM 2016. [DOI: 10.1515/zpch-2016-0825] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Abstract
In photosynthetic reaction centers, reduction of the secondary acceptors leads to triplet charge recombination of the primary radical pair (RP). This process is spin selective and in a magnetic field it populates only the T0 state of the donor triplet state. As a result, the triplet state of the donor has a distinctive spin polarization pattern that can be measured by transient electron paramagnetic resonance (TREPR) spectroscopy. In heliobacterial reaction centers (HbRCs), the primary donor, P800, is composed of two bacteriochlorophyll g′ molecules and its triplet state has not been studied as extensively as those of other reaction centers. Here, we present TREPR and optically detected magnetic resonance (ODMR) data of 3P800 and show that although it can be detected by ODMR it is not observed in the TREPR data. We demonstrate that the absence of the TREPR spectrum is a result of the fact that the zero-field splitting (ZFS) tensor of 3P800 is maximally rhombic, which results in complete cancelation of the absorptive and emissive polarization in randomly oriented samples.
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Affiliation(s)
- Bryan Ferlez
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA 16802, United States of America
| | - Alessandro Agostini
- Dipartimento di Scienze Chimiche, Università di Padova, Via Marzolo, 1, 35131 Padova, Italy
| | - Donatella Carbonera
- Dipartimento di Scienze Chimiche, Università di Padova, Via Marzolo, 1, 35131 Padova, Italy
| | - John H. Golbeck
- Department of Biochemistry and Molecular Biology and Department of Chemistry, The Pennsylvania State University, University Park, PA 16802, United States of America
- Freiburg Institute of Advanced Studies (FRIAS), Albert-Ludwigs-Universität Freiburg, Albertstr.19, 79104 Freiburg, Germany
| | - Art van der Est
- Freiburg Institute of Advanced Studies (FRIAS), Albert-Ludwigs-Universität Freiburg, Albertstr.19, 79104 Freiburg, Germany
- Departments of Chemistry and Physics, Brock University, 1812 Sir Isaac Brock Way, St. Catharines, ON, Canada L2S 3A1
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17
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Kondo T, Matsuoka M, Azai C, Itoh S, Oh-oka H. Orientations of Iron–Sulfur Clusters FA and FB in the Homodimeric Type-I Photosynthetic Reaction Center of Heliobacterium modesticaldum. J Phys Chem B 2016; 120:4204-12. [DOI: 10.1021/acs.jpcb.6b01112] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Toru Kondo
- Division
of Material Science (Physics), Graduate School of Science, Nagoya University, Furocho, Chikusa, Nagoya 464-8602, Japan
| | - Masahiro Matsuoka
- Department
of Biological Sciences, Graduate School of Science, Osaka University, Osaka 560-0043, Japan
| | - Chihiro Azai
- Department
of Biological Sciences, Graduate School of Science, Osaka University, Osaka 560-0043, Japan
| | - Shigeru Itoh
- Center
for Gene Research, Nagoya University, Furocho, Chikusa, Nagoya 464-8602, Japan
| | - Hirozo Oh-oka
- Department
of Biological Sciences, Graduate School of Science, Osaka University, Osaka 560-0043, Japan
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18
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Ferlez B, Cowgill J, Dong W, Gisriel C, Lin S, Flores M, Walters K, Cetnar D, Redding KE, Golbeck JH. Thermodynamics of the Electron Acceptors in Heliobacterium modesticaldum: An Exemplar of an Early Homodimeric Type I Photosynthetic Reaction Center. Biochemistry 2016; 55:2358-70. [PMID: 27033441 DOI: 10.1021/acs.biochem.5b01320] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The homodimeric type I reaction center in heliobacteria is arguably the simplest known pigment-protein complex capable of conducting (bacterio)chlorophyll-based conversion of light into chemical energy. Despite its structural simplicity, the thermodynamics of the electron transfer cofactors on the acceptor side have not been fully investigated. In this work, we measured the midpoint potential of the terminal [4Fe-4S](2+/1+) cluster (FX) in reaction centers from Heliobacterium modesticaldum. The FX cluster was titrated chemically and monitored by (i) the decrease in the level of stable P800 photobleaching by optical spectroscopy, (ii) the loss of the light-induced g ≈ 2 radical from P800(+•) following a single-turnover flash, (iii) the increase in the low-field resonance at 140 mT attributed to the S = (3)/2 ground spin state of FX(-), and (iv) the loss of the spin-correlated P800(+) FX(-) radical pair following a single-turnover flash. These four techniques led to similar estimations of the midpoint potential for FX of -502 ± 3 mV (n = 0.99), -496 ± 2 mV (n = 0.99), -517 ± 10 mV (n = 0.65), and -501 ± 4 mV (n = 0.84), respectively, with a consensus value of -504 ± 10 mV (converging to n = 1). Under conditions in which FX is reduced, the long-lived (∼15 ms) P800(+) FX(-) state is replaced by a rapidly recombining (∼15 ns) P800(+)A0(-) state, as shown by ultrafast optical experiments. There was no evidence of the presence of a P800(+) A1(-) spin-correlated radical pair by electron paramagnetic resonance (EPR) under these conditions. The midpoint potentials of the two [4Fe-4S](2+/1+) clusters in the low-molecular mass ferredoxins were found to be -480 ± 11 mV/-524 ± 13 mV for PshBI, -453 ± 6 mV/-527 ± 6 mV for PshBII, and -452 ± 5 mV/-533 ± 8 mV for HM1_2505 as determined by EPR spectroscopy. FX is therefore suitably poised to reduce one [4Fe-4S](2+/1+) cluster in these mobile electron carriers. Using the measured midpoint potential of FX and a quasi-equilibrium model of charge recombination, the midpoint potential of A0 was estimated to be -854 mV at room temperature. The midpoint potentials of A0 and FX are therefore 150-200 mV less reducing than their respective counterparts in Photosystem I of cyanobacteria and plants. This places the redox potential of the FX cluster in heliobacteria approximately equipotential to the highest-potential iron-sulfur cluster (FA) in Photosystem I, consistent with its assignment as the terminal electron acceptor.
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Affiliation(s)
- Bryan Ferlez
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University , University Park, Pennsylvania 16802, United States
| | - John Cowgill
- School of Molecular Sciences, Arizona State University , Tempe, Arizona 85287, United States
| | - Weibing Dong
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University , University Park, Pennsylvania 16802, United States
| | - Christopher Gisriel
- School of Molecular Sciences, Arizona State University , Tempe, Arizona 85287, United States
| | - Su Lin
- School of Molecular Sciences, Arizona State University , Tempe, Arizona 85287, United States
| | - Marco Flores
- School of Molecular Sciences, Arizona State University , Tempe, Arizona 85287, United States
| | - Karim Walters
- Department of Chemistry, The Pennsylvania State University , University Park, Pennsylvania 16802, United States
| | - Daniel Cetnar
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University , University Park, Pennsylvania 16802, United States
| | - Kevin E Redding
- School of Molecular Sciences, Arizona State University , Tempe, Arizona 85287, United States
| | - John H Golbeck
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University , University Park, Pennsylvania 16802, United States.,Department of Chemistry, The Pennsylvania State University , University Park, Pennsylvania 16802, United States
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19
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Nowicka B, Kruk J. Powered by light: Phototrophy and photosynthesis in prokaryotes and its evolution. Microbiol Res 2016; 186-187:99-118. [PMID: 27242148 DOI: 10.1016/j.micres.2016.04.001] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2015] [Revised: 02/12/2016] [Accepted: 04/01/2016] [Indexed: 11/29/2022]
Abstract
Photosynthesis is a complex metabolic process enabling photosynthetic organisms to use solar energy for the reduction of carbon dioxide into biomass. This ancient pathway has revolutionized life on Earth. The most important event was the development of oxygenic photosynthesis. It had a tremendous impact on the Earth's geochemistry and the evolution of living beings, as the rise of atmospheric molecular oxygen enabled the development of a highly efficient aerobic metabolism, which later led to the evolution of complex multicellular organisms. The mechanism of photosynthesis has been the subject of intensive research and a great body of data has been accumulated. However, the evolution of this process is not fully understood, and the development of photosynthesis in prokaryota in particular remains an unresolved question. This review is devoted to the occurrence and main features of phototrophy and photosynthesis in prokaryotes. Hypotheses concerning the origin and spread of photosynthetic traits in bacteria are also discussed.
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Affiliation(s)
- Beatrycze Nowicka
- Department of Plant Physiology and Biochemistry, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Gronostajowa 7, 30-387 Kraków, Poland.
| | - Jerzy Kruk
- Department of Plant Physiology and Biochemistry, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Gronostajowa 7, 30-387 Kraków, Poland.
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20
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Ferlez B, Dong W, Siavashi R, Redding K, Hou HJM, Golbeck JH, van der Est A. The Effect of Bacteriochlorophyll g Oxidation on Energy and Electron Transfer in Reaction Centers from Heliobacterium modesticaldum. J Phys Chem B 2015; 119:13714-25. [PMID: 26030062 DOI: 10.1021/acs.jpcb.5b03339] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The heliobacteria are a family of strictly anaerobic, Gram-positive, photoheterotrophs in the Firmicutes. They make use of a homodimeric type I reaction center (RC) that contains ∼20 antenna bacteriochlorophyll (BChl) g molecules, a special pair of BChl g' molecules (P800), two 8(1)-OH-Chl aF molecules (A0), a [4Fe-4S] iron-sulfur cluster (FX), and a carotenoid (4,4'-diaponeurosporene). It is known that in the presence of light and oxygen BChl g is converted to a species with an absorption spectrum identical to that of Chl a. Here, we show that main product of the conversion is 8(1)-OH-Chl aF. Smaller amounts of two other oxidized Chl aF species are also produced. In the presence of light and oxygen, the kinetics of the conversion are monophasic and temperature dependent, with an activation energy of 66 ± 2 kJ mol(-1). In the presence of oxygen in the dark, the conversion occurs in two temperature-dependent kinetic phases: a slow phase followed by a fast phase with an activation energy of 53 ± 1 kJ mol(-1). The loss of BChl g' occurs at the same rate as the loss of Bchl g; hence, the special pair converts at the same rate as the antenna Chl's. However, the loss of P800 photooxidiation and flavodoxin reduction is not linear with the loss of BChl g. In anaerobic RCs, the charge recombination between P800(+) and FX(-) at 80 K is monophasic with a lifetime of 4.2 ms, but after exposure to oxygen, an additional phase with a lifetime of 0.3 ms is observed. Transient EPR data show that the line width of P800(+) increases as BChl g is converted to Chl aF and the rate of electron transfer from A0 to FX, as estimated from the net polarization generated by singlet-triplet mixing during the lifetime of P800(+)A0(-), is unchanged. The transient EPR data also show that conversion of the BChl g results in increased formation of triplet states of both BChl g and Chl aF. The nonlinear loss of P800 photooxidiation and flavodoxin reduction, the biphasic backreaction kinetics, and the increased EPR line width of P800(+) are all consistent with a model in which the BChl g'/BChl g' and BChl g'/Chl aF' special pairs are functional but the Chl aF'/Chl aF' special pair is not.
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Affiliation(s)
| | | | | | - Kevin Redding
- Department of Chemistry & Biochemistry, Arizona State University , Tempe, Arizona 85287, United States
| | - Harvey J M Hou
- Department of Physical Sciences, Alabama State University , Montgomery, Alabama 36104, United States
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21
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Yang JH, Sarrou I, Martin-Garcia JM, Zhang S, Redding KE, Fromme P. Purification and biochemical characterization of the ATP synthase from Heliobacterium modesticaldum. Protein Expr Purif 2015; 114:1-8. [PMID: 25979464 DOI: 10.1016/j.pep.2015.05.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2015] [Revised: 04/28/2015] [Accepted: 05/06/2015] [Indexed: 11/26/2022]
Abstract
Heliobacterium modesticaldum is an anaerobic photosynthetic bacterium that grows optimally at pH 6-7 and 52°C and is the only phototrophic member of the Firmicutes phylum family (gram-positive bacteria with low GC content). The ATP synthase of H. modesticaldum was isolated and characterized at the biochemical and biophysical levels. The isolated holoenzyme exhibited the subunit patterns of F-type ATP synthases containing a 5-subunit hydrophilic F1 subcomplex and a 3-subunit hydrophobic F0 subcomplex. ATP hydrolysis by the isolated HF1F0 ATP synthase was successfully detected after pretreatment with different detergents by an in-gel ATPase activity assay, which showed that the highest activity was detected in the presence of mild detergents such as LDAO; moreover, high catalytic activity in the gel was already detected after the initial incubation period of 0.5h. In contrast, HF1F0 showed extremely low ATPase activity in harsher detergents such as TODC. The isolated fully functional enzyme will form the basis for future structural studies.
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Affiliation(s)
- Jay-How Yang
- Department of Chemistry and Biochemistry, Arizona State University, Tempe, AZ 85287-1604, USA; Center for Applied Structural Discovery, The Biodesign Institute, Arizona State University, Tempe, AZ 85287-1604, USA
| | - Iosifina Sarrou
- Department of Chemistry and Biochemistry, Arizona State University, Tempe, AZ 85287-1604, USA; Institute of Molecular Biology & Biotechnology, Foundation for Research & Technology-Hellas, Nikolaou Plastira 100, GR-70013 Heraklion, Crete, Greece
| | - Jose M Martin-Garcia
- Department of Chemistry and Biochemistry, Arizona State University, Tempe, AZ 85287-1604, USA; Center for Applied Structural Discovery, The Biodesign Institute, Arizona State University, Tempe, AZ 85287-1604, USA
| | - Shangji Zhang
- School of Life Sciences, Arizona State University, Tempe, AZ 85287-1604, USA
| | - Kevin E Redding
- Department of Chemistry and Biochemistry, Arizona State University, Tempe, AZ 85287-1604, USA
| | - Petra Fromme
- Department of Chemistry and Biochemistry, Arizona State University, Tempe, AZ 85287-1604, USA; Center for Applied Structural Discovery, The Biodesign Institute, Arizona State University, Tempe, AZ 85287-1604, USA.
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22
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Zhang Y, Majumder ELW, Yue H, Blankenship RE, Gross ML. Structural analysis of diheme cytochrome c by hydrogen-deuterium exchange mass spectrometry and homology modeling. Biochemistry 2014; 53:5619-30. [PMID: 25138816 PMCID: PMC4159202 DOI: 10.1021/bi500420y] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
![]()
A lack
of X-ray or nuclear magnetic resonance structures of proteins
inhibits their further study and characterization, motivating the
development of new ways of analyzing structural information without
crystal structures. The combination of hydrogen–deuterium exchange
mass spectrometry (HDX-MS) data in conjunction with homology modeling
can provide improved structure and mechanistic predictions. Here a
unique diheme cytochrome c (DHCC) protein from Heliobacterium modesticaldum is studied with both HDX and homology modeling to bring some definition of the structure of the
protein and its role. Specifically, HDX data were used to guide the
homology modeling to yield a more functionally relevant structural
model of DHCC.
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Affiliation(s)
- Ying Zhang
- Department of Chemistry, Washington University in St. Louis , St. Louis, Missouri 63130, United States
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23
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Kashey TS, Cowgill JB, McConnell MD, Flores M, Redding KE. Expression and characterization of cytochrome c553 from Heliobacterium modesticaldum. PHOTOSYNTHESIS RESEARCH 2014; 120:291-299. [PMID: 24557489 DOI: 10.1007/s11120-014-9982-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2013] [Accepted: 02/05/2014] [Indexed: 06/03/2023]
Abstract
Cytochrome c553 of Heliobacterium modesticaldum is the donor to P800 (+), the primary electron donor of the heliobacterial reaction center (HbRC). It is a membrane-anchored 14-kDa cytochrome that accomplishes electron transfer from the cytochrome bc complex to the HbRC. The petJ gene encoding cyt c 553 was cloned and expressed in Escherichia coli with a hexahistidine tag replacing the lipid attachment site to create a soluble donor that could be made in a preparative scale. The recombinant cytochrome had spectral characteristics typical of a c-type cytochrome, including an asymmetric α-band, and a slightly red-shifted Soret band when reduced. The EPR spectrum of the oxidized protein was characteristic of a low-spin cytochrome. The midpoint potential of the recombinant cytochrome was +217 ± 10 mV. The interaction between soluble recombinant cytochrome c 553 and the HbRC was also studied. Re-reduction of photooxidized P800 (+) was accelerated by addition of reduced cytochrome c 553. The kinetics were characteristic of a bimolecular reaction with a second order rate of 1.53 × 10(4) M(-1) s(-1) at room temperature. The rate manifested a steep temperature dependence, with a calculated activation energy of 91 kJ mol(-1), similar to that of the native protein in Heliobacillus gestii cells. These data demonstrate that the recombinant soluble cytochrome is comparable to the native protein, and likely lacks a discrete electrostatic binding site on the HbRC.
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Affiliation(s)
- Trevor S Kashey
- Department of Chemistry and Biochemistry, Arizona State University, Tempe, AZ, 85287-1604, USA
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24
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Redding KE, Sarrou I, Rappaport F, Santabarbara S, Lin S, Reifschneider KT. Modulation of the fluorescence yield in heliobacterial cells by induction of charge recombination in the photosynthetic reaction center. PHOTOSYNTHESIS RESEARCH 2014; 120:221-235. [PMID: 24318506 DOI: 10.1007/s11120-013-9957-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2013] [Accepted: 11/25/2013] [Indexed: 06/02/2023]
Abstract
Heliobacteria contain a very simple photosynthetic apparatus, consisting of a homodimeric type I reaction center (RC) without a peripheral antenna system and using the unique pigment bacteriochlorophyll (BChl) g. They are thought to use a light-driven cyclic electron transport pathway to pump protons, and thereby phosphorylate ADP, although some of the details of this cycle are yet to be worked out. We previously reported that the fluorescence emission from the heliobacterial RC in vivo was increased by exposure to actinic light, although this variable fluorescence phenomenon exhibited very different characteristics to that in oxygenic phototrophs (Collins et al. 2010). Here, we describe the underlying mechanism behind the variable fluorescence in heliobacterial cells. We find that the ability to stably photobleach P800, the primary donor of the RC, using brief flashes is inversely correlated to the variable fluorescence. Using pump-probe spectroscopy in the nanosecond timescale, we found that illumination of cells with bright light for a few seconds put them in a state in which a significant fraction of the RCs underwent charge recombination from P800 (+)A0 (-) with a time constant of ~20 ns. The fraction of RCs in the rapidly back-reacting state correlated very well with the variable fluorescence, indicating that nearly all of the increase in fluorescence could be explained by charge recombination of P800 (+)A0 (-), some of which regenerated the singlet excited state. This hypothesis was tested directly by time-resolved fluorescence studies in the ps and ns timescales. The major decay component in whole cells had a 20-ps decay time, representing trapping by the RC. Treatment of cells with dithionite resulted in the appearance of a ~18-ns decay component, which accounted for ~0.6 % of the decay, but was almost undetectable in the untreated cells. We conclude that strong illumination of heliobacterial cells can result in saturation of the electron acceptor pool, leading to reduction of the acceptor side of the RC and the creation of a back-reacting RC state that gives rise to delayed fluorescence.
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Affiliation(s)
- Kevin E Redding
- Department of Chemistry and Biochemistry, Arizona State University, 1711 S. Rural Rd., Tempe, AZ, 85287-1604, USA,
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25
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Chauvet A, Sarrou J, Lin S, Romberger SP, Golbeck JH, Savikhin S, Redding KE. Temporal and spectral characterization of the photosynthetic reaction center from Heliobacterium modesticaldum. PHOTOSYNTHESIS RESEARCH 2013; 116:1-9. [PMID: 23812833 DOI: 10.1007/s11120-013-9871-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2012] [Accepted: 06/11/2013] [Indexed: 06/02/2023]
Abstract
A time-resolved spectroscopic study of the isolated photosynthetic reaction center (RC) from Heliobacterium modesticaldum reveals that thermal equilibration of light excitation among the antenna pigments followed by trapping of excitation and the formation of the charge-separated state P800 (+)A0 (-) occurs within ~25 ps. This time scale is similar to that reported for plant and cyanobacterial photosystem I (PS I) complexes. Subsequent electron transfer from the primary electron acceptor A0 occurs with a lifetime of ~600 ps, suggesting that the RC of H. modesticaldum is functionally similar to that of Heliobacillus mobilis and Heliobacterium chlorum. The (A0 (-) - A0) and (P800 (+) - P800) absorption difference spectra imply that an 8(1)-OH-Chl a F molecule serves as the primary electron acceptor and occupies the position analogous to ec3 (A0) in PS I, while a monomeric BChl g pigment occupies the position analogous to ec2 (accessory Chl). The presence of an intense photobleaching band at 790 nm in the (A0 (-) - A0) spectrum suggests that the excitonic coupling between the monomeric accessory BChl g and the 8(1)-OH-Chl a F in the heliobacterial RC is significantly stronger than the excitonic coupling between the equivalent pigments in PS I.
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Affiliation(s)
- Adrien Chauvet
- Department of Physics, Purdue University, 525 Northwestern Ave, West Lafayette, IN 47907, USA
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26
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Sousa FL, Shavit-Grievink L, Allen JF, Martin WF. Chlorophyll biosynthesis gene evolution indicates photosystem gene duplication, not photosystem merger, at the origin of oxygenic photosynthesis. Genome Biol Evol 2013; 5:200-16. [PMID: 23258841 PMCID: PMC3595025 DOI: 10.1093/gbe/evs127] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
An open question regarding the evolution of photosynthesis is how cyanobacteria came to possess the two reaction center (RC) types, Type I reaction center (RCI) and Type II reaction center (RCII). The two main competing theories in the foreground of current thinking on this issue are that either 1) RCI and RCII are related via lineage divergence among anoxygenic photosynthetic bacteria and became merged in cyanobacteria via an event of large-scale lateral gene transfer (also called "fusion" theories) or 2) the two RC types are related via gene duplication in an ancestral, anoxygenic but protocyanobacterial phototroph that possessed both RC types before making the transition to using water as an electron donor. To distinguish between these possibilities, we studied the evolution of the core (bacterio)chlorophyll biosynthetic pathway from protoporphyrin IX (Proto IX) up to (bacterio)chlorophyllide a. The results show no dichotomy of chlorophyll biosynthesis genes into RCI- and RCII-specific chlorophyll biosynthetic clades, thereby excluding models of fusion at the origin of cyanobacteria and supporting the selective-loss hypothesis. By considering the cofactor demands of the pathway and the source genes from which several steps in chlorophyll biosynthesis are derived, we infer that the cell that first synthesized chlorophyll was a cobalamin-dependent, heme-synthesizing, diazotrophic anaerobe.
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Affiliation(s)
- Filipa L Sousa
- Institute of Molecular Evolution, University of Düsseldorf, Düsseldorf, Germany.
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