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Lübben MK, Klingl A, Nickelsen J, Ostermeier M. CLEM, a universal tool for analyzing structural organization in thylakoid membranes. PHYSIOLOGIA PLANTARUM 2024; 176:e14417. [PMID: 38945684 DOI: 10.1111/ppl.14417] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Accepted: 05/15/2024] [Indexed: 07/02/2024]
Abstract
Chlorophyll (Chl) plays a crucial role in photosynthesis, functioning as a photosensitizer. As an integral component of this process, energy absorbed by this pigment is partly emitted as red fluorescence. This signal can be readily imaged by fluorescence microscopy and provides a visualization of photosynthetic activity. However, due to limited resolution, signals cannot be assigned to specific subcellular/organellar membrane structures. By correlating fluorescence micrographs with transmission electron microscopy, researchers can identify sub-cellular compartments and membranes, enabling the monitoring of Chl distribution within thylakoid membrane substructures in cyanobacteria, algae, and higher plant single cells. Here, we describe a simple and effective protocol for correlative light-electron microscopy (CLEM) based on the autofluorescence of Chl and demonstrate its application to selected photosynthetic model organisms. Our findings illustrate the potential of this technique to identify areas of high Chl concentration and photochemical activity, such as grana regions in vascular plants, by mapping stacked thylakoids.
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Affiliation(s)
- Maximilian K Lübben
- Department of Molecular Plant Science, LMU Munich, Planegg-Martinsried, Germany
| | - Andreas Klingl
- Plant Development, LMU Munich, Planegg-Martinsried, Germany
| | - Jörg Nickelsen
- Department of Molecular Plant Science, LMU Munich, Planegg-Martinsried, Germany
| | - Matthias Ostermeier
- Department of Molecular Plant Science, LMU Munich, Planegg-Martinsried, Germany
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2
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Paris T, Kiss A, Signor L, Lutfalla G, Blaise M, Boeri Erba E, Chaloin L, Yatime L. The IbeA protein from adherent invasive Escherichia coli is a flavoprotein sharing structural homology with FAD-dependent oxidoreductases. FEBS J 2024; 291:177-203. [PMID: 37786987 DOI: 10.1111/febs.16969] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Revised: 09/22/2023] [Accepted: 09/29/2023] [Indexed: 10/04/2023]
Abstract
Invasion of brain endothelium protein A (IbeA) is a virulence factor specific to pathogenic Escherichia coli. Originally identified in the K1 strain causing neonatal meningitis, it was more recently found in avian pathogenic Escherichia coli (APEC) and adherent invasive Escherichia coli (AIEC). In these bacteria, IbeA facilitates host cell invasion and intracellular survival, in particular, under harsh conditions like oxidative stress. Furthermore, IbeA from AIEC contributes to intramacrophage survival and replication, thus enhancing the inflammatory response within the intestine. Therefore, this factor is a promising drug target for anti-AIEC strategies in the context of Crohn's disease. Despite such an important role, the biological function of IbeA remains largely unknown. In particular, its exact nature and cellular localization, i.e., membrane-bound invasin versus cytosolic factor, are still of debate. Here, we developed an efficient protocol for recombinant expression of IbeA under native conditions and demonstrated that IbeA from AIEC is a soluble, homodimeric flavoprotein. Using mass spectrometry and tryptophan fluorescence measurements, we further showed that IbeA preferentially binds flavin adenine dinucleotide (FAD), with an affinity in the one-hundred nanomolar range and optimal binding under reducing conditions. 3D-modeling with AlphaFold revealed that IbeA shares strong structural homology with FAD-dependent oxidoreductases. Finally, we used ligand docking, mutational analyses, and molecular dynamics simulations to identify the FAD binding pocket within IbeA and characterize possible conformational changes occurring upon ligand binding. Overall, we suggest that the role of IbeA in the survival of AIEC within host cells, notably macrophages, is linked to modulation of redox processes.
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Affiliation(s)
- Théo Paris
- LPHI, Univ. Montpellier, CNRS, INSERM, France
| | - Agneta Kiss
- Univ. Grenoble Alpes, CEA, CNRS, IBS, Grenoble, France
| | - Luca Signor
- Univ. Grenoble Alpes, CEA, CNRS, IBS, Grenoble, France
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Chen GE, Hunter CN. Engineering Chlorophyll, Bacteriochlorophyll, and Carotenoid Biosynthetic Pathways in Escherichia coli. ACS Synth Biol 2023; 12:2236-2244. [PMID: 37531642 PMCID: PMC10443036 DOI: 10.1021/acssynbio.3c00237] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2023] [Indexed: 08/04/2023]
Abstract
The biosynthesis of chlorophylls (Chls) and bacteriochlorophylls (BChls) represents a key aspect of photosynthesis research. Our previous work assembled the complete pathway for the synthesis of Chl a in Escherichia coli; here we engineer the more complex BChl a pathway in the same heterotrophic host. Coexpression of 18 genes enabled E. coli to produce BChl a, verifying that we have identified the minimum set of genes for the BChl a biosynthesis pathway. The protochlorophyllide reduction step was mediated by the bchNBL genes, and this same module was used to modify the Chl a pathway previously constructed in E. coli, eliminating the need for the light-dependent protochlorophyllide reductase. Furthermore, we demonstrate the feasibility of synthesizing more than one family of photosynthetic pigments in one host by engineering E. coli strains that accumulate the carotenoids neurosporene and β-carotene in addition to BChl a.
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Affiliation(s)
- Guangyu E. Chen
- State
Key Laboratory of Microbial Metabolism, School of Life Sciences and
Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China
| | - C. Neil Hunter
- School
of Biosciences, University of Sheffield, Sheffield S10 2TN, United Kingdom
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Kim J, Lee JK, Kim EJ. Chlorophyll a Synthesis in Rhodobacter sphaeroides by Chlorophyll Synthase of Nicotiana tabacum. BIOLOGY 2023; 12:biology12040573. [PMID: 37106772 PMCID: PMC10136183 DOI: 10.3390/biology12040573] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2023] [Revised: 04/05/2023] [Accepted: 04/08/2023] [Indexed: 04/29/2023]
Abstract
The production of phytylated chlorophyll a (Chl aP) in Rhodobacter sphaeroides, which uses phytylated bacteriochlorophyll a (BChl aP), is the first step in expanding the light absorption spectra. Unlike the chlorophyll synthase (ChlG) of the Synechocystis sp. PCC6803, ChlGs of angiosperms, including Arabidopsis thaliana, Nicotiana tabacum, Avena sativa, and Oryza sativa, showed bacteriochlorophyll synthase activity and resistance to inhibition by bacteriochlorophyllide a (BChlide a), geranylgeranylated BChl a (BChl aGG), and BChl aP, collectively called bacteriochlorins. Among the angiosperm ChlGs, N. tabacum ChlG had the highest bacteriochlorophyll synthase activity and resistance to inhibition by bacteriochlorins. Expression of N. tabacum chlG in R. sphaeroides resulted in the formation of free Chl aP in the presence of BChl aP during photoheterotrophic growth, even though reactive oxygen species were generated.
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Affiliation(s)
- June Kim
- Department of Life Science, Sogang University, Seoul 04107, Republic of Korea
| | - Jeong K Lee
- Department of Life Science, Sogang University, Seoul 04107, Republic of Korea
| | - Eui-Jin Kim
- Microbial Research Department, Nakdonggang National Institute of Biological Resources, Sangju 37242, Republic of Korea
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Kim J, Kim C, Kim S, Ihee H, Shin W, Kim EJ, Lee JK. The Photoactive Photosynthetic Reaction Center of a Rhodobacter sphaeroides Mutant Lacking 3-Vinyl (Bacterio)Chlorophyllide a Hydratase Contains 3-Vinyl Bacteriochlorophyll a. Microbiol Spectr 2023; 11:e0387822. [PMID: 36971575 PMCID: PMC10101016 DOI: 10.1128/spectrum.03878-22] [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: 09/22/2022] [Accepted: 02/20/2023] [Indexed: 03/29/2023] Open
Abstract
Rhodobacter sphaeroides mutant BF-lacking 3-vinyl (bacterio)chlorophyllide a hydratase (BchF)-accumulates chlorophyllide a (Chlide a) and 3-vinyl bacteriochlorophyllide a (3V-Bchlide a). BF synthesizes 3-vinyl bacteriochlorophyll a (3V-Bchl a) through prenylation of 3V-Bchlide a and assembles a novel reaction center (V-RC) using 3V-Bchl a and Mg-free 3-vinyl bacteriopheophytin a (3V-Bpheo a) at a molar ratio of 2:1. We aimed to verify whether a bchF-deleted R. sphaeroides mutant produces a photochemically active RC that facilitates photoheterotrophic growth. The mutant grew photoheterotrophically-implying a functional V-RC-as confirmed by the emergence of growth-competent suppressors of bchC-deleted mutant (BC) under irradiation. Suppressor mutations in BC were localized to bchF, which diminished BchF activity and caused 3V-Bchlide a accumulation. bchF expression carrying the suppressor mutations in trans resulted in the coproduction of V-RC and wild-type RC (WT-RC) in BF. The V-RC had a time constant (τ) for electron transfer from the primary electron donor P (a dimer of 3V-Bchl a) to the A-side containing 3V-Bpheo a (HA) similar to that of the WT-RC and a 60% higher τ for electron transfer from HA to quinone A (QA). Thus, the electron transfer from HA to QA in the V-RC should be slower than that in the WT-RC. Furthermore, the midpoint redox potential of P/P+ of the V-RC was 33 mV more positive than that of the WT-RC. R. sphaeroides, thus, synthesizes the V-RC when 3V-Bchlide a accumulates. The V-RC can support photoheterotrophic growth; however, its photochemical activity is inferior to that of the WT-RC. IMPORTANCE 3V-Bchlide a is an intermediate in the bacteriochlorophyll a (Bchl a)-specific biosynthetic branch and prenylated by bacteriochlorophyll synthase. R. sphaeroides synthesizes V-RC that absorbs light at short wavelengths. The V-RC was not previously discovered because 3V-Bchlide a does not accumulate during the growth of WT cells synthesizing Bchl a. The levels of reactive oxygen species increased with the onset of photoheterotrophic growth in BF, resulting in a long lag period. Although the inhibitor of BchF is unknown, the V-RC may act as a substitute for the WT-RC when BchF is completely inhibited. Alternatively, it may act synergistically with WT-RC at low levels of BchF activity. The V-RC may broaden the absorption spectra of R. sphaeroides and supplement its photosynthetic ability at various wavelengths of visible light to a greater extent than that by the WT-RC alone.
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Affiliation(s)
- June Kim
- Department of Life Science, Sogang University, Seoul, Republic of Korea
| | - Changwon Kim
- Department of Chemistry and KI for the BioCentury, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Republic of Korea
- Center for Advanced Reaction Dynamics, Institute for Basic Science, Daejeon, Republic of Korea
| | - Siin Kim
- Department of Chemistry and KI for the BioCentury, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Republic of Korea
- Center for Advanced Reaction Dynamics, Institute for Basic Science, Daejeon, Republic of Korea
| | - Hyotcherl Ihee
- Department of Chemistry and KI for the BioCentury, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Republic of Korea
- Center for Advanced Reaction Dynamics, Institute for Basic Science, Daejeon, Republic of Korea
| | - Woonsup Shin
- Department of Chemistry, Sogang University, Seoul, Republic of Korea
| | - Eui-Jin Kim
- Microbial Research Department, Nakdonggang National Institute of Biological Resources, Gyeongsangbuk-do, Republic of Korea
| | - Jeong K. Lee
- Department of Life Science, Sogang University, Seoul, Republic of Korea
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Jackson PJ, Hitchcock A, Brindley AA, Dickman MJ, Hunter CN. Absolute quantification of cellular levels of photosynthesis-related proteins in Synechocystis sp. PCC 6803. PHOTOSYNTHESIS RESEARCH 2023; 155:219-245. [PMID: 36542271 PMCID: PMC9958174 DOI: 10.1007/s11120-022-00990-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Accepted: 11/24/2022] [Indexed: 06/17/2023]
Abstract
Quantifying cellular components is a basic and important step for understanding how a cell works, how it responds to environmental changes, and for re-engineering cells to produce valuable metabolites and increased biomass. We quantified proteins in the model cyanobacterium Synechocystis sp. PCC 6803 given the general importance of cyanobacteria for global photosynthesis, for synthetic biology and biotechnology research, and their ancestral relationship to the chloroplasts of plants. Four mass spectrometry methods were used to quantify cellular components involved in the biosynthesis of chlorophyll, carotenoid and bilin pigments, membrane assembly, the light reactions of photosynthesis, fixation of carbon dioxide and nitrogen, and hydrogen and sulfur metabolism. Components of biosynthetic pathways, such as those for chlorophyll or for photosystem II assembly, range between 1000 and 10,000 copies per cell, but can be tenfold higher for CO2 fixation enzymes. The most abundant subunits are those for photosystem I, with around 100,000 copies per cell, approximately 2 to fivefold higher than for photosystem II and ATP synthase, and 5-20 fold more than for the cytochrome b6f complex. Disparities between numbers of pathway enzymes, between components of electron transfer chains, and between subunits within complexes indicate possible control points for biosynthetic processes, bioenergetic reactions and for the assembly of multisubunit complexes.
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Affiliation(s)
- Philip J Jackson
- Plants, Photosynthesis and Soil, School of Biosciences, University of Sheffield, Sheffield, S10 2TN, UK.
- Department of Chemical and Biological Engineering, University of Sheffield, Sheffield, S1 3JD, UK.
| | - Andrew Hitchcock
- Plants, Photosynthesis and Soil, School of Biosciences, University of Sheffield, Sheffield, S10 2TN, UK
| | - Amanda A Brindley
- Plants, Photosynthesis and Soil, School of Biosciences, University of Sheffield, Sheffield, S10 2TN, UK
| | - Mark J Dickman
- Department of Chemical and Biological Engineering, University of Sheffield, Sheffield, S1 3JD, UK
| | - C Neil Hunter
- Plants, Photosynthesis and Soil, School of Biosciences, University of Sheffield, Sheffield, S10 2TN, UK
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Proctor MS, Sutherland GA, Canniffe DP, Hitchcock A. The terminal enzymes of (bacterio)chlorophyll biosynthesis. ROYAL SOCIETY OPEN SCIENCE 2022; 9:211903. [PMID: 35573041 PMCID: PMC9066304 DOI: 10.1098/rsos.211903] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Accepted: 03/29/2022] [Indexed: 05/03/2023]
Abstract
(Bacterio)chlorophylls are modified tetrapyrroles that are used by phototrophic organisms to harvest solar energy, powering the metabolic processes that sustain most of the life on Earth. Biosynthesis of these pigments involves enzymatic modification of the side chains and oxidation state of a porphyrin precursor, modifications that differ by species and alter the absorption properties of the pigments. (Bacterio)chlorophylls are coordinated by proteins that form macromolecular assemblies to absorb light and transfer excitation energy to a special pair of redox-active (bacterio)chlorophyll molecules in the photosynthetic reaction centre. Assembly of these pigment-protein complexes is aided by an isoprenoid moiety esterified to the (bacterio)chlorin macrocycle, which anchors and stabilizes the pigments within their protein scaffolds. The reduction of the isoprenoid 'tail' and its addition to the macrocycle are the final stages in (bacterio)chlorophyll biosynthesis and are catalysed by two enzymes, geranylgeranyl reductase and (bacterio)chlorophyll synthase. These enzymes work in conjunction with photosynthetic complex assembly factors and the membrane biogenesis machinery to synchronize delivery of the pigments to the proteins that coordinate them. In this review, we summarize current understanding of the catalytic mechanism, substrate recognition and regulation of these crucial enzymes and their involvement in thylakoid biogenesis and photosystem repair in oxygenic phototrophs.
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Affiliation(s)
- Matthew S. Proctor
- Plants, Photosynthesis and Soil, School of Biosciences, University of Sheffield, Firth Court, Western Bank, Sheffield S10 2TN, UK
| | - George A. Sutherland
- Plants, Photosynthesis and Soil, School of Biosciences, University of Sheffield, Firth Court, Western Bank, Sheffield S10 2TN, UK
| | - Daniel P. Canniffe
- Biochemistry and Systems Biology, Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Crown Street, Liverpool L69 7ZB, UK
| | - Andrew Hitchcock
- Plants, Photosynthesis and Soil, School of Biosciences, University of Sheffield, Firth Court, Western Bank, Sheffield S10 2TN, UK
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