1
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Gorbunov MY, Falkowski PG. Using picosecond fluorescence lifetime analysis to determine photosynthesis in the world's oceans. Photosynth Res 2024; 159:253-259. [PMID: 38019308 DOI: 10.1007/s11120-023-01060-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2023] [Accepted: 10/31/2023] [Indexed: 11/30/2023]
Abstract
Phytoplankton in the ocean account for less than 1% of the global photosynthetic biomass, but contribute about 45% of the photosynthetically fixed carbon on Earth. This amazing production/biomass ratio implies a very high photosynthetic efficiency. But, how efficiently is the absorbed light used in marine photosynthesis? The introduction of picosecond and then femtosecond lasers for kinetic measurements in mid 1970s to 90 s was a revolution in basic photosynthesis research that vastly improved our understanding of the energy conversion processes in photosynthetic reactions. Until recently, the use of this technology in the ocean was not feasible due to the complexity of related instrumentation and the lack of picosecond lasers suitable for routine operation in the field. However, recent advances in solid-state laser technology and the development of compact data acquisition electronics led to the application of picosecond fluorescence lifetime analyses in the field. Here, we review the development of operational ultrasensitive picosecond fluorescence instruments to infer photosynthetic energy conversion processes in ocean ecosystems. This analysis revealed that, in spite of the high production/biomass ratio in marine phytoplankton, the photosynthetic energy conversion efficiency is exceptionally low-on average, ca. 50% of its maximum potential, suggesting that most of the contemporary open ocean surface waters are extremely nutrient deficient.
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Affiliation(s)
- Maxim Y Gorbunov
- Environmental Biophysics and Molecular Ecology Program, Department of Marine and Coastal Sciences, Rutgers, The State University of New Jersey, New Brunswick, NJ, USA.
| | - Paul G Falkowski
- Environmental Biophysics and Molecular Ecology Program, Department of Marine and Coastal Sciences, Rutgers, The State University of New Jersey, New Brunswick, NJ, USA
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2
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McGuinness KN, Fehon N, Feehan R, Miller M, Mutter AC, Rybak LA, Nam J, AbuSalim JE, Atkinson JT, Heidari H, Losada N, Kim JD, Koder RL, Lu Y, Silberg JJ, Slusky JSG, Falkowski PG, Nanda V. The energetics and evolution of oxidoreductases in deep time. Proteins 2024; 92:52-59. [PMID: 37596815 DOI: 10.1002/prot.26563] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2023] [Accepted: 07/06/2023] [Indexed: 08/20/2023]
Abstract
The core metabolic reactions of life drive electrons through a class of redox protein enzymes, the oxidoreductases. The energetics of electron flow is determined by the redox potentials of organic and inorganic cofactors as tuned by the protein environment. Understanding how protein structure affects oxidation-reduction energetics is crucial for studying metabolism, creating bioelectronic systems, and tracing the history of biological energy utilization on Earth. We constructed ProtReDox (https://protein-redox-potential.web.app), a manually curated database of experimentally determined redox potentials. With over 500 measurements, we can begin to identify how proteins modulate oxidation-reduction energetics across the tree of life. By mapping redox potentials onto networks of oxidoreductase fold evolution, we can infer the evolution of electron transfer energetics over deep time. ProtReDox is designed to include user-contributed submissions with the intention of making it a valuable resource for researchers in this field.
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Affiliation(s)
- Kenneth N McGuinness
- Department of Natural Sciences, Caldwell University, Caldwell, New Jersey, USA
- Center for Advanced Biotechnology and Medicine, Rutgers University, Piscataway, New Jersey, USA
| | - Nolan Fehon
- Environmental Biophysics and Molecular Ecology Program, Department of Marine and Coastal Sciences, Rutgers University, New Brunswick, New Jersey, USA
| | - Ryan Feehan
- Computational Biology Program, The University of Kansas, Lawrence, Kansas, USA
| | - Michelle Miller
- Environmental Biophysics and Molecular Ecology Program, Department of Marine and Coastal Sciences, Rutgers University, New Brunswick, New Jersey, USA
| | - Andrew C Mutter
- Department of Physics, The City College of New York, New York, New York, USA
| | - Laryssa A Rybak
- Department of Physics, The City College of New York, New York, New York, USA
| | - Justin Nam
- Center for Advanced Biotechnology and Medicine, Rutgers University, Piscataway, New Jersey, USA
| | - Jenna E AbuSalim
- Center for Advanced Biotechnology and Medicine, Rutgers University, Piscataway, New Jersey, USA
| | - Joshua T Atkinson
- Department of Chemical and Biomolecular Engineering, Rice University, Houston, Texas, USA
| | - Hirbod Heidari
- Department of Chemistry, University of Texas at Austin, Austin, Texas, USA
| | - Natalie Losada
- Center for Advanced Biotechnology and Medicine, Rutgers University, Piscataway, New Jersey, USA
| | - J Dongun Kim
- Environmental Biophysics and Molecular Ecology Program, Department of Marine and Coastal Sciences, Rutgers University, New Brunswick, New Jersey, USA
| | - Ronald L Koder
- Department of Physics, The City College of New York, New York, New York, USA
| | - Yi Lu
- Department of Chemistry, University of Texas at Austin, Austin, Texas, USA
| | - Jonathan J Silberg
- Department of Chemical and Biomolecular Engineering, Rice University, Houston, Texas, USA
| | - Joanna S G Slusky
- Computational Biology Program, The University of Kansas, Lawrence, Kansas, USA
- Department of Molecular Biosciences, The University of Kansas, Lawrence, Kansas, USA
| | - Paul G Falkowski
- Environmental Biophysics and Molecular Ecology Program, Department of Marine and Coastal Sciences, Rutgers University, New Brunswick, New Jersey, USA
- Department of Earth and Planetary Sciences, Rutgers University, New Brunswick, New Jersey, USA
| | - Vikas Nanda
- Center for Advanced Biotechnology and Medicine, Rutgers University, Piscataway, New Jersey, USA
- Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, Rutgers University, Piscataway, New Jersey, USA
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3
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Farr O, Hao J, Liu W, Fehon N, Reinfelder JR, Yee N, Falkowski PG. Archean phosphorus recycling facilitated by ultraviolet radiation. Proc Natl Acad Sci U S A 2023; 120:e2307524120. [PMID: 37459508 PMCID: PMC10372543 DOI: 10.1073/pnas.2307524120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Accepted: 06/06/2023] [Indexed: 07/29/2023] Open
Abstract
Of the six elements incorporated into the major polymers of life, phosphorus is the least abundant on a global scale [E. Anders, M. Ebihara, Geochim. Cosmochim. Acta 46, 2363-2380 (1982)] and has been described as the "ultimate limiting nutrient" [T. Tyrrell, Nature 400, 525-531 (1999)]. In the modern ocean, the supply of dissolved phosphorus is predominantly sustained by the oxidative remineralization/recycling of organic phosphorus in seawater. However, in the Archean Eon (4 to 2.5 Ga), surface waters were anoxic and reducing. Here, we conducted photochemical experiments to test whether photodegradation of ubiquitous dissolved organic phosphorus could facilitate phosphorus recycling under the simulated Archean conditions. Our results strongly suggest that organic phosphorus compounds, which were produced by marine biota (e.g., adenosine monophosphate and phosphatidylserine) or delivered by meteorites (e.g., methyl phosphonate) can undergo rapid photodegradation and release inorganic phosphate into solution under anoxic conditions. Our experimental results and theoretical calculations indicate that photodegradation of organic phosphorus could have been a significant source of bioavailable phosphorus in the early ocean and would have fueled primary production during the Archean eon.
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Affiliation(s)
- Orion Farr
- Department of Earth and Planetary Science, Rutgers University, Piscataway, NJ08854-8066
- Centre Interdisciplinaire de Nanoscience de Marseille (UMR 7325 CNRS), Aix Marseille Université, Campus de Luminy – Case 913, Marseille Cedex 0913288, France
| | - Jihua Hao
- Deep Space Exploration Laboratory/Chinese Academy of Sciences Key Laboratory of Crust-Mantle Materials and Environments, University of Science and Technology of China, Hefei230026, China
- Department of Marine and Coastal Sciences, Rutgers University, New Brunswick, NJ08901
| | - Winnie Liu
- Department of Earth and Planetary Science, Rutgers University, Piscataway, NJ08854-8066
| | - Nolan Fehon
- Department of Marine and Coastal Sciences, Rutgers University, New Brunswick, NJ08901
| | - John R. Reinfelder
- Department of Environmental Sciences, Rutgers University, New Brunswick, NJ08901
| | - Nathan Yee
- Department of Earth and Planetary Science, Rutgers University, Piscataway, NJ08854-8066
- Department of Environmental Sciences, Rutgers University, New Brunswick, NJ08901
| | - Paul G. Falkowski
- Department of Earth and Planetary Science, Rutgers University, Piscataway, NJ08854-8066
- Department of Marine and Coastal Sciences, Rutgers University, New Brunswick, NJ08901
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4
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Agarwal A, Levitan O, Cruz de Carvalho H, Falkowski PG. Light-dependent signal transduction in the marine diatom Phaeodactylum tricornutum. Proc Natl Acad Sci U S A 2023; 120:e2216286120. [PMID: 36897974 PMCID: PMC10089185 DOI: 10.1073/pnas.2216286120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2022] [Accepted: 02/09/2023] [Indexed: 03/12/2023] Open
Abstract
Unlike most higher plants, unicellular algae can acclimate to changes in irradiance on time scales of hours to a few days. The process involves an enigmatic signaling pathway originating in the plastid that leads to coordinated changes in plastid and nuclear gene expression. To deepen our understanding of this process, we conducted functional studies to examine how the model diatom, Phaeodactylum tricornutum, acclimates to low light and sought to identify the molecules responsible for the phenomenon. We show that two transformants with altered expression of two putative signal transduction molecules, a light-specific soluble kinase and a plastid transmembrane protein, that appears to be regulated by a long noncoding natural antisense transcript, arising from the opposite strand, are physiologically incapable of photoacclimation. Based on these results, we propose a working model of the retrograde feedback in the signaling and regulation of photoacclimation in a marine diatom.
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Affiliation(s)
- Ananya Agarwal
- Environmental Biophysics and Molecular Ecology Program, Department of Marine and Coastal Sciences, Rutgers University, New Brunswick, NJ08901
- Department of Biochemistry and Microbiology, Rutgers University, New Brunswick, NJ08901
| | - Orly Levitan
- Environmental Biophysics and Molecular Ecology Program, Department of Marine and Coastal Sciences, Rutgers University, New Brunswick, NJ08901
- Department of Biochemistry and Microbiology, Rutgers University, New Brunswick, NJ08901
| | - Helena Cruz de Carvalho
- Institut de Biologie de l’ENS, Ecole normale supérieure, CNRS, Inserm, Université Paris Sciences & Letters, Paris75005, France
- Faculté des Sciences et Technologie, Université Paris Est-Créteil94000Créteil, France
| | - Paul G. Falkowski
- Environmental Biophysics and Molecular Ecology Program, Department of Marine and Coastal Sciences, Rutgers University, New Brunswick, NJ08901
- Department of Earth and Planetary Sciences, Rutgers University, Piscataway, NJ08854
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5
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Timm J, Pike DH, Mancini JA, Tyryshkin AM, Poudel S, Siess JA, Molinaro PM, McCann JJ, Waldie KM, Koder RL, Falkowski PG, Nanda V. Design of a minimal di-nickel hydrogenase peptide. Sci Adv 2023; 9:eabq1990. [PMID: 36897954 PMCID: PMC10005181 DOI: 10.1126/sciadv.abq1990] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2022] [Accepted: 02/07/2023] [Indexed: 06/07/2023]
Abstract
Ancestral metabolic processes involve the reversible oxidation of molecular hydrogen by hydrogenase. Extant hydrogenase enzymes are complex, comprising hundreds of amino acids and multiple cofactors. We designed a 13-amino acid nickel-binding peptide capable of robustly producing molecular hydrogen from protons under a wide variety of conditions. The peptide forms a di-nickel cluster structurally analogous to a Ni-Fe cluster in [NiFe] hydrogenase and the Ni-Ni cluster in acetyl-CoA synthase, two ancient, extant proteins central to metabolism. These experimental results demonstrate that modern enzymes, despite their enormous complexity, likely evolved from simple peptide precursors on early Earth.
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Affiliation(s)
- Jennifer Timm
- Environmental Biophysics and Molecular Ecology Program, Department of Marine and Coastal Sciences and Department of Earth and Planetary Sciences, Rutgers University, New Brunswick, NJ 08901, USA
- Center for Advanced Biotechnology and Medicine and the Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, Rutgers University, Piscataway, NJ 08854, USA
| | - Douglas H. Pike
- Center for Advanced Biotechnology and Medicine and the Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, Rutgers University, Piscataway, NJ 08854, USA
| | - Joshua A. Mancini
- Environmental Biophysics and Molecular Ecology Program, Department of Marine and Coastal Sciences and Department of Earth and Planetary Sciences, Rutgers University, New Brunswick, NJ 08901, USA
- Center for Advanced Biotechnology and Medicine and the Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, Rutgers University, Piscataway, NJ 08854, USA
| | - Alexei M. Tyryshkin
- Environmental Biophysics and Molecular Ecology Program, Department of Marine and Coastal Sciences and Department of Earth and Planetary Sciences, Rutgers University, New Brunswick, NJ 08901, USA
- Center for Advanced Biotechnology and Medicine and the Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, Rutgers University, Piscataway, NJ 08854, USA
| | - Saroj Poudel
- Environmental Biophysics and Molecular Ecology Program, Department of Marine and Coastal Sciences and Department of Earth and Planetary Sciences, Rutgers University, New Brunswick, NJ 08901, USA
- Center for Advanced Biotechnology and Medicine and the Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, Rutgers University, Piscataway, NJ 08854, USA
| | - Jan A. Siess
- Center for Advanced Biotechnology and Medicine and the Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, Rutgers University, Piscataway, NJ 08854, USA
| | - Paul M. Molinaro
- Department of Physics, The City College of New York, New York, NY 10016, USA
| | - James J. McCann
- Department of Physics, The City College of New York, New York, NY 10016, USA
| | - Kate M. Waldie
- Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, NJ 08854, USA
| | - Ronald L. Koder
- Department of Physics, The City College of New York, New York, NY 10016, USA
| | - Paul G. Falkowski
- Environmental Biophysics and Molecular Ecology Program, Department of Marine and Coastal Sciences and Department of Earth and Planetary Sciences, Rutgers University, New Brunswick, NJ 08901, USA
| | - Vikas Nanda
- Center for Advanced Biotechnology and Medicine and the Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, Rutgers University, Piscataway, NJ 08854, USA
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6
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McGuinness KN, Klau GW, Morrison SM, Moore EK, Seipp J, Falkowski PG, Nanda V. Evaluating Mineral Lattices as Evolutionary Proxies for Metalloprotein Evolution. ORIGINS LIFE EVOL B 2022; 52:263-275. [DOI: 10.1007/s11084-022-09630-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Accepted: 10/03/2022] [Indexed: 11/17/2022]
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7
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Agarwal A, Di R, Falkowski PG. Light-harvesting complex gene regulation by a MYB-family transcription factor in the marine diatom, Phaeodactylum tricornutum. Photosynth Res 2022; 153:59-70. [PMID: 35391595 DOI: 10.1007/s11120-022-00915-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Accepted: 03/16/2022] [Indexed: 06/14/2023]
Abstract
Unicellular photoautotrophs adapt to variations in light intensity by changing the abundance of light harvest pigment-protein complexes (LHCs) on time scales of hours to days. This process requires a feedback signal between the plastid (where light intensity is sensed) to the nucleus (where the genes for LHCs are encoded). The signals must include heretofore unidentified transcription factors that modify the expression level of the LHCs. Analysis of the nuclear genome of the model diatom Phaeodactylum tricornutum revealed that all the lhc genes have potential binding sites for transcription factors belonging to the MYB-family proteins. Functional studies involving antisense RNA interference of a hypothetical protein with a MYB DNA-binding domain were performed. The resultant strains with altered photosynthetic and physiological characteristics lost their ability to acclimate to changes in irradiance; i.e., cellular chlorophyll content became independent of growth irradiance. Our results strongly suggest that the inter-organellar signaling cascade was disrupted, and the cell could no longer communicate the environmental signal from the plastid to the nucleus. Here, we identify, for the first time, an LHC Regulating Myb (LRM) transcription factor, which we propose is involved in lhc gene regulation and photoacclimation mechanisms in response to changes in light intensity.
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Affiliation(s)
- Ananya Agarwal
- Environmental Biophysics and Molecular Ecology Program, Department of Marine and Coastal Sciences, Rutgers University, New Brunswick, NJ, USA
- Department of Biochemistry and Microbiology, Rutgers University, New Brunswick, NJ, USA
| | - Rong Di
- Department of Plant Biology, Rutgers University, New Brunswick, NJ, USA
| | - Paul G Falkowski
- Environmental Biophysics and Molecular Ecology Program, Department of Marine and Coastal Sciences, Rutgers University, New Brunswick, NJ, USA.
- Department of Earth and Planetary Sciences, Rutgers University, Piscataway, NJ, USA.
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8
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Cheong KY, Jouhet J, Maréchal E, Falkowski PG. The redox state of the plastoquinone (PQ) pool is connected to thylakoid lipid saturation in a marine diatom. Photosynth Res 2022; 153:71-82. [PMID: 35389175 DOI: 10.1007/s11120-022-00914-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Accepted: 03/14/2022] [Indexed: 06/14/2023]
Abstract
The redox state of the plastoquinone (PQ) pool is a known sensor for retrograde signaling. In this paper, we asked, "does the redox state of the PQ pool modulate the saturation state of thylakoid lipids?" Data from fatty acid composition and mRNA transcript abundance analyses suggest a strong connection between these two aspects in a model marine diatom. Fatty acid profiles of Phaeodactylum tricornutum exhibited specific changes when the redox state of the PQ pool was modulated by light and two chemical inhibitors [3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) or 2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone (DBMIB)]. Data from liquid chromatography with tandem mass spectrometry (LC-MS/MS) indicated a ca. 7-20% decrease in the saturation state of all four conserved thylakoid lipids in response to an oxidized PQ pool. The redox signals generated from an oxidized PQ pool in plastids also increased the mRNA transcript abundance of nuclear-encoded C16 fatty acid desaturases (FADs), with peak upregulation on a timescale of 6 to 12 h. The connection between the redox state of the PQ pool and thylakoid lipid saturation suggests a heretofore unrecognized retrograde signaling pathway that couples photosynthetic electron transport and the physical state of thylakoid membrane lipids.
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Affiliation(s)
- Kuan Yu Cheong
- Environmental Biophysics and Molecular Ecology Program, Department of Marine and Coastal Sciences, Rutgers, The State University of New Jersey, New Brunswick, NJ, 08901, USA
- Department of Plant Biology, Rutgers, The State University of New Jersey, New Brunswick, NJ, 08901, USA
| | - Juliette Jouhet
- Laboratoire de Physiologie Cellulaire et Végétale, Unité Mixte Recherche 5168, Centre National Recherche Scientifique, Commissariat à l'Energie Atomique et aux Energies Alternatives, INRAE, Université Grenoble Alpes, 5168, Grenoble Cedex 9, France
| | - Eric Maréchal
- Laboratoire de Physiologie Cellulaire et Végétale, Unité Mixte Recherche 5168, Centre National Recherche Scientifique, Commissariat à l'Energie Atomique et aux Energies Alternatives, INRAE, Université Grenoble Alpes, 5168, Grenoble Cedex 9, France
| | - Paul G Falkowski
- Environmental Biophysics and Molecular Ecology Program, Department of Marine and Coastal Sciences, Rutgers, The State University of New Jersey, New Brunswick, NJ, 08901, USA.
- Department of Plant Biology, Rutgers, The State University of New Jersey, New Brunswick, NJ, 08901, USA.
- Department of Earth and Planetary Sciences, Rutgers, The State University of New Jersey, Piscataway, NJ, 08854, USA.
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9
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Hao J, Liu W, Goff JL, Steadman JA, Large RR, Falkowski PG, Yee N. Anoxic photochemical weathering of pyrite on Archean continents. Sci Adv 2022; 8:eabn2226. [PMID: 35767603 PMCID: PMC9242442 DOI: 10.1126/sciadv.abn2226] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Accepted: 05/10/2022] [Indexed: 06/15/2023]
Abstract
Sulfur is an essential element of life that is assimilated by Earth's biosphere through the chemical breakdown of pyrite. On the early Earth, pyrite weathering by atmospheric oxygen was severely limited, and low marine sulfate concentrations persisted for much of the Archean eon. Here, we show an anoxic photochemical mechanism of pyrite weathering that could have provided substantial amounts of sulfate to the oceans as continents formed in the late Archean. Pyrite grains suspended in anoxic ferrous iron solutions produced millimolar sulfate concentrations when irradiated with ultraviolet light. The Fe2+(aq) was photooxidized, which, in turn, led to the chemical oxidation of pyritic sulfur. Additional experiments conducted with 2.68 Ga shale demonstrated that photochemically derived ferric iron oxidizes and dissolves sedimentary pyrite during chemical weathering. The results suggest that before the rise of atmospheric oxygen, oxidative pyrite weathering on Archean continents was controlled by the exposure of land to sunlight.
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Affiliation(s)
- Jihua Hao
- Department of Marine and Coastal Sciences, Rutgers University, New Brunswick, NJ 08901, USA
- CAS Key Laboratory of Crust-Mantle Materials and Environments, School of Earth and Space Sciences, University of Science and Technology of China, Hefei 230026, China
| | - Winnie Liu
- Department of Earth and Planetary Sciences, Rutgers University, Piscataway, NJ 08854, USA
| | - Jennifer L. Goff
- Department of Earth and Planetary Sciences, Rutgers University, Piscataway, NJ 08854, USA
| | - Jeffrey A. Steadman
- CODES, Centre for Ore Deposit and Earth Sciences, University of Tasmania, Hobart, TAS 7001, Australia
| | - Ross R. Large
- CODES, Centre for Ore Deposit and Earth Sciences, University of Tasmania, Hobart, TAS 7001, Australia
| | - Paul G. Falkowski
- Department of Marine and Coastal Sciences, Rutgers University, New Brunswick, NJ 08901, USA
- Department of Earth and Planetary Sciences, Rutgers University, Piscataway, NJ 08854, USA
| | - Nathan Yee
- Department of Earth and Planetary Sciences, Rutgers University, Piscataway, NJ 08854, USA
- Department of Environmental Sciences, Rutgers University, New Brunswick, NJ 08901, USA
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10
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Bromberg Y, Aptekmann AA, Mahlich Y, Cook L, Senn S, Miller M, Nanda V, Ferreiro DU, Falkowski PG. Quantifying structural relationships of metal-binding sites suggests origins of biological electron transfer. Sci Adv 2022; 8:eabj3984. [PMID: 35030025 PMCID: PMC8759750 DOI: 10.1126/sciadv.abj3984] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Accepted: 11/22/2021] [Indexed: 06/07/2023]
Abstract
Biological redox reactions drive planetary biogeochemical cycles. Using a novel, structure-guided sequence analysis of proteins, we explored the patterns of evolution of enzymes responsible for these reactions. Our analysis reveals that the folds that bind transition metal–containing ligands have similar structural geometry and amino acid sequences across the full diversity of proteins. Similarity across folds reflects the availability of key transition metals over geological time and strongly suggests that transition metal–ligand binding had a small number of common peptide origins. We observe that structures central to our similarity network come primarily from oxidoreductases, suggesting that ancestral peptides may have also facilitated electron transfer reactions. Last, our results reveal that the earliest biologically functional peptides were likely available before the assembly of fully functional protein domains over 3.8 billion years ago.Thus, life is a special, very complex form of motion of matter, but this form did not always exist, and it is not separated from inorganic nature by an impassable abyss; rather, it arose from inorganic nature as a new property in the process of evolution of the world. We must study the history of this evolution if we want to solve the problem of the origin of life. [A. I. Oparin (1)]
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Affiliation(s)
- Yana Bromberg
- Department of Biochemistry and Microbiology, Rutgers University, 76 Lipman Dr, New Brunswick, NJ 08873, USA
| | - Ariel A. Aptekmann
- Department of Biochemistry and Microbiology, Rutgers University, 76 Lipman Dr, New Brunswick, NJ 08873, USA
| | - Yannick Mahlich
- Department of Biochemistry and Microbiology, Rutgers University, 76 Lipman Dr, New Brunswick, NJ 08873, USA
| | - Linda Cook
- Program in Applied and Computational Math, Princeton University, Princeton, NJ 08540, USA
| | - Stefan Senn
- Department of Biochemistry and Microbiology, Rutgers University, 76 Lipman Dr, New Brunswick, NJ 08873, USA
| | - Maximillian Miller
- Department of Biochemistry and Microbiology, Rutgers University, 76 Lipman Dr, New Brunswick, NJ 08873, USA
| | - Vikas Nanda
- Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, and Center for Advanced Biotechnology and Medicine, Rutgers University, Piscataway, NJ 08854, USA
| | - Diego U. Ferreiro
- Protein Physiology Lab, Departamento de Química Biológica, Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales (IQUIBICEN-CONICET), Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Paul G. Falkowski
- Environmental Biophysics and Molecular Ecology Program, Department of Marine and Coastal Sciences, Rutgers University, New Brunswick, NJ 08901, USA
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11
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Abstract
Approximately 45% of the photosynthetically fixed carbon on Earth occurs in the oceans in phytoplankton, which account for less than 1% of the world's photosynthetic biomass. This amazing empirical observation implies a very high photosynthetic energy conversion efficiency, but how efficiently is the solar energy actually used? The photon energy budget of photosynthesis can be divided into three terms: the quantum yields of photochemistry, fluorescence, and heat. Measuring two of these three processes closes the energy budget. The development of ultrasensitive, seagoing chlorophyll variable fluorescence and picosecond fluorescence lifetime instruments has allowed independent closure on the first two terms. With this closure, we can understand how phytoplankton respond to nutrient supplies on timescales of hours to months and, over longer timescales, to changes in climate.
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Affiliation(s)
- Maxim Y Gorbunov
- Environmental Biophysics and Molecular Ecology Program, Department of Marine and Coastal Sciences, Rutgers, The State University of New Jersey, New Brunswick, New Jersey 08901, USA; ,
| | - Paul G Falkowski
- Environmental Biophysics and Molecular Ecology Program, Department of Marine and Coastal Sciences, Rutgers, The State University of New Jersey, New Brunswick, New Jersey 08901, USA; ,
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12
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Jiang J, Cheong KY, Falkowski PG, Dai W. Integrating on-grid immunogold labeling and cryo-electron tomography to reveal photosystem II structure and spatial distribution in thylakoid membranes. J Struct Biol 2021; 213:107746. [PMID: 34010667 PMCID: PMC8577061 DOI: 10.1016/j.jsb.2021.107746] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2020] [Revised: 05/10/2021] [Accepted: 05/13/2021] [Indexed: 11/17/2022]
Abstract
A long-standing challenge in cell biology is elucidating the structure and spatial distribution of individual membrane-bound proteins, protein complexes and their interactions in their native environment. Here, we describe a workflow that combines on-grid immunogold labeling, followed by cryo-electron tomography (cryoET) imaging and structural analyses to identify and characterize the structure of photosystem II (PSII) complexes. Using an antibody specific to a core subunit of PSII, the D1 protein (uniquely found in the water splitting complex in all oxygenic photoautotrophs), we identified PSII complexes in biophysically active thylakoid membranes isolated from a model marine diatom Phaeodactylum tricornutum. Subsequent cryoET analyses of these protein complexes resolved two PSII structures: supercomplexes and dimeric cores. Our integrative approach establishes the structural signature of multimeric membrane protein complexes in their native environment and provides a pathway to elucidate their high-resolution structures.
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Affiliation(s)
- Jennifer Jiang
- Department of Cell Biology and Neuroscience, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, United States; Institute for Quantitative Biomedicine, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, United States
| | - Kuan Yu Cheong
- Environmental Biophysics and Molecular Ecology Program, Department of Marine and Coastal Sciences, Rutgers, The State University of New Jersey, New Brunswick, NJ 08901, United States; Department of Plant Biology, Rutgers, The State University of New Jersey, New Brunswick, NJ 08901, United States
| | - Paul G Falkowski
- Institute for Quantitative Biomedicine, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, United States; Environmental Biophysics and Molecular Ecology Program, Department of Marine and Coastal Sciences, Rutgers, The State University of New Jersey, New Brunswick, NJ 08901, United States; Department of Earth and Planetary Sciences, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, United States
| | - Wei Dai
- Department of Cell Biology and Neuroscience, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, United States; Institute for Quantitative Biomedicine, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, United States.
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13
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Cheong KY, Firlar E, Ficaro L, Gorbunov MY, Kaelber JT, Falkowski PG. Saturation of thylakoid-associated fatty acids facilitates bioenergetic coupling in a marine diatom allowing for thermal acclimation. Glob Chang Biol 2021; 27:3133-3144. [PMID: 33749034 DOI: 10.1111/gcb.15612] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2020] [Accepted: 03/03/2021] [Indexed: 06/12/2023]
Abstract
In a rapidly warming world, we ask, "What limits the potential of marine diatoms to acclimate to elevated temperatures?," a group of ecologically successful unicellular eukaryotic photoautotrophs that evolved in a cooler ocean and are critical to marine food webs. To this end, we examined thermal tolerance mechanisms related to photosynthesis in the sequenced and transformable model diatom Phaeodactylum tricornutum. Data from transmission electron microscopy (TEM) and fatty acid methyl ester-gas chromatography mass spectrometry (FAME-GCMS) suggest that saturating thylakoid-associated fatty acids allowed rapid (on the order of hours) thermal tolerance up to 28.5°C. Beyond this critical temperature, thylakoid ultrastructure became severely perturbed. Biophysical analyses revealed that electrochemical leakage through the thylakoid membranes was extremely sensitive to elevated temperature (Q10 of 3.5). Data suggest that the loss of the proton motive force (pmf) occurred even when heat-labile photosystem II (PSII) was functioning, and saturation of thylakoid-associated fatty acids was active. Indeed, growth was inhibited when leakage of pmf through thylakoid membranes was insufficiently compensated by proton input from PSII. Our findings provide a mechanistic understanding of the importance of rapid saturation of thylakoid-associated fatty acids for ultrastructure maintenance and a generation of pmf at elevated temperatures. To the extent these experimental results apply, the ability of diatoms to generate a pmf may be a sensitive parameter for thermal sensitivity diagnosis in phytoplankton.
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Affiliation(s)
- Kuan Yu Cheong
- Environmental Biophysics and Molecular Ecology Program, Department of Marine and Coastal Sciences, Rutgers, The State University of New Jersey, New Brunswick, NJ, USA
- Department of Plant Biology, Rutgers, The State University of New Jersey, New Brunswick, NJ, USA
| | - Emre Firlar
- Institute for Quantitative Biomedicine, Rutgers, The State University of New Jersey, Piscataway, NJ, USA
- Rutgers New Jersey Cryo-Electron Microscopy & Tomography Core Facility, Rutgers, The State University of New Jersey, Piscataway, NJ, USA
| | - Lia Ficaro
- Institute for Quantitative Biomedicine, Rutgers, The State University of New Jersey, Piscataway, NJ, USA
- Rutgers New Jersey Cryo-Electron Microscopy & Tomography Core Facility, Rutgers, The State University of New Jersey, Piscataway, NJ, USA
| | - Maxim Y Gorbunov
- Environmental Biophysics and Molecular Ecology Program, Department of Marine and Coastal Sciences, Rutgers, The State University of New Jersey, New Brunswick, NJ, USA
| | - Jason T Kaelber
- Institute for Quantitative Biomedicine, Rutgers, The State University of New Jersey, Piscataway, NJ, USA
- Rutgers New Jersey Cryo-Electron Microscopy & Tomography Core Facility, Rutgers, The State University of New Jersey, Piscataway, NJ, USA
| | - Paul G Falkowski
- Environmental Biophysics and Molecular Ecology Program, Department of Marine and Coastal Sciences, Rutgers, The State University of New Jersey, New Brunswick, NJ, USA
- Department of Earth and Planetary Sciences, Rutgers, The State University of New Jersey, Piscataway, NJ, USA
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14
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Abstract
Coral skeletons are materials composed of inorganic aragonitic fibres and organic molecules including proteins, sugars and lipids that are highly organized to form a solid biomaterial upon which the animals live. The skeleton contains tens of proteins, all of which are encoded in the animal genome and secreted during the biomineralization process. While recent advances are revealing the functions and evolutionary history of some of these proteins, how they are spatially arranged in the skeleton is unknown. Using a combination of chemical cross-linking and high-resolution tandem mass spectrometry, we identify, for the first time, the spatial interactions of the proteins embedded within the skeleton of the stony coral Stylophora pistillata. Our subsequent network analysis revealed that several coral acid-rich proteins are invariably associated with carbonic anhydrase(s), alpha-collagen, cadherins and other calcium-binding proteins. These spatial arrangements clearly show that protein-protein interactions in coral skeletons are highly coordinated and are key to understanding the formation and persistence of coral skeletons through time.
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Affiliation(s)
- Manjula P Mummadisetti
- Environmental Biophysics and Molecular Biology Program, Department of Marine and Coastal Sciences, Rutgers, The State University of New Jersey, 71 Dudley Rd, New Brunswick, NJ 08901, USA
| | - Jeana L Drake
- Department of Earth, Planetary, and Space Sciences, University of California, Los Angeles, 595 Charles E. Young Drive East, Los Angeles, CA 90095, USA.,Department of Marine Biology, University of Haifa, 199 Aba Khoushy Avenue, Mount Carmel, Haifa 2498838, Israel
| | - Paul G Falkowski
- Environmental Biophysics and Molecular Biology Program, Department of Marine and Coastal Sciences, Rutgers, The State University of New Jersey, 71 Dudley Rd, New Brunswick, NJ 08901, USA.,Department of Earth and Planetary Sciences, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA
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15
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Sherman J, Gorbunov MY, Schofield O, Falkowski PG. Photosynthetic energy conversion efficiency in the West Antarctic Peninsula. Limnol Oceanogr 2020; 65:2912-2925. [PMID: 33380749 PMCID: PMC7754432 DOI: 10.1002/lno.11562] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Revised: 04/18/2020] [Accepted: 06/23/2020] [Indexed: 06/12/2023]
Abstract
The West Antarctic Peninsula (WAP) is a highly productive polar ecosystem where phytoplankton dynamics are regulated by intense bottom-up control from light and iron availability. Rapid climate change along the WAP is driving shifts in the mixed layer depth and iron availability. Elucidating the relative role of each of these controls and their interactions is crucial for understanding of how primary productivity will change in coming decades. Using a combination of ultra-high-resolution variable chlorophyll fluorescence together with fluorescence lifetime analyses on the 2017 Palmer Long Term Ecological Research cruise, we mapped the temporal and spatial variability in phytoplankton photophysiology across the WAP. Highest photosynthetic energy conversion efficiencies and lowest fluorescence quantum yields were observed in iron replete coastal regions. Photosynthetic energy conversion efficiencies decreased by ~ 60% with a proportional increase in quantum yields of thermal dissipation and fluorescence on the outer continental shelf and slope. The combined analysis of variable fluorescence and lifetimes revealed that, in addition to the decrease in the fraction of inactive reaction centers, up to 20% of light harvesting chlorophyll-protein antenna complexes were energetically uncoupled from photosystem II reaction centers in iron-limited phytoplankton. These biophysical signatures strongly suggest severe iron limitation of photosynthesis in the surface waters along the continental slope of the WAP.
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Affiliation(s)
- Jonathan Sherman
- Environmental Biophysics and Molecular Ecology Program, Department of Marine and Coastal Sciences, RutgersThe State University of New JerseyNew BrunswickNew JerseyUSA
| | - Maxim Y. Gorbunov
- Environmental Biophysics and Molecular Ecology Program, Department of Marine and Coastal Sciences, RutgersThe State University of New JerseyNew BrunswickNew JerseyUSA
| | - Oscar Schofield
- Environmental Biophysics and Molecular Ecology Program, Department of Marine and Coastal Sciences, RutgersThe State University of New JerseyNew BrunswickNew JerseyUSA
- Center for Ocean Observing Leadership, Department of Marine and Coastal SciencesRutgers, The State University of New JerseyNew BrunswickNew JerseyUSA
| | - Paul G. Falkowski
- Environmental Biophysics and Molecular Ecology Program, Department of Marine and Coastal Sciences, RutgersThe State University of New JerseyNew BrunswickNew JerseyUSA
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16
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Von Euw S, Azaïs T, Manichev V, Laurent G, Pehau-Arnaudet G, Rivers M, Murali N, Kelly DJ, Falkowski PG. Solid-State Phase Transformation and Self-Assembly of Amorphous Nanoparticles into Higher-Order Mineral Structures. J Am Chem Soc 2020; 142:12811-12825. [PMID: 32568532 DOI: 10.1021/jacs.0c05591] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Materials science has been informed by nonclassical pathways to crystallization, based on biological processes, about the fabrication of damage-tolerant composite materials. Various biomineralizing taxa, such as stony corals, deposit metastable, magnesium-rich, amorphous calcium carbonate nanoparticles that further assemble and transform into higher-order mineral structures. Here, we examine a similar process in abiogenic conditions using synthetic, amorphous calcium magnesium carbonate nanoparticles. Applying a combination of high-resolution imaging and in situ solid-state nuclear magnetic resonance spectroscopy, we reveal the underlying mechanism of the solid-state phase transformation of these amorphous nanoparticles into crystals under aqueous conditions. These amorphous nanoparticles are covered by a hydration shell of bound water molecules. Fast chemical exchanges occur: the hydrogens present within the nanoparticles exchange with the hydrogens from the surface-bound H2O molecules which, in turn, exchange with the hydrogens of the free H2O molecule of the surrounding aqueous medium. This cascade of chemical exchanges is associated with an enhanced mobility of the ions/molecules that compose the nanoparticles which, in turn, allow for their rearrangement into crystalline domains via solid-state transformation. Concurrently, the starting amorphous nanoparticles aggregate and form ordered mineral structures through crystal growth by particle attachment. Sphere-like aggregates and spindle-shaped structures were, respectively, formed from relatively high or low weights per volume of the same starting amorphous nanoparticles. These results offer promising prospects for exerting control over such a nonclassical pathway to crystallization to design mineral structures that could not be achieved through classical ion-by-ion growth.
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Affiliation(s)
- Stanislas Von Euw
- Environmental Biophysics and Molecular Ecology Program, Department of Marine and Coastal Sciences, Rutgers University, 71 Dudley Road, New Brunswick, New Jersey 08901, United States.,Trinity Centre for Bioengineering, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin 2, D02 R590, Ireland
| | - Thierry Azaïs
- Laboratoire de Chimie de la Matière Condensée de Paris, Sorbonne Université, CNRS, 4 place Jussieu, F-75005, Paris, France
| | - Viacheslav Manichev
- Department of Chemistry and Chemical Biology, Rutgers University, 123 Bevier Road, Piscataway, New Jersey 08854, United States.,Institute of Advanced Materials, Devices, and Nanotechnology, Rutgers University, 607 Taylor Road, Piscataway, New Jersey 08854, United States
| | - Guillaume Laurent
- Laboratoire de Chimie de la Matière Condensée de Paris, Sorbonne Université, CNRS, 4 place Jussieu, F-75005, Paris, France
| | - Gérard Pehau-Arnaudet
- UMR 3528 and UTech UBI, Institut Pasteur, 28 rue du Docteur Roux, F-75015 Paris, France
| | - Margarita Rivers
- Institute of Advanced Materials, Devices, and Nanotechnology, Rutgers University, 607 Taylor Road, Piscataway, New Jersey 08854, United States.,Department of Physics, Wellesley College, 106 Central Street, Wellesley, Massachusetts 02481, United States
| | - Nagarajan Murali
- Department of Chemistry and Chemical Biology, Rutgers University, 123 Bevier Road, Piscataway, New Jersey 08854, United States
| | - Daniel J Kelly
- Trinity Centre for Bioengineering, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin 2, D02 R590, Ireland
| | - Paul G Falkowski
- Environmental Biophysics and Molecular Ecology Program, Department of Marine and Coastal Sciences, Rutgers University, 71 Dudley Road, New Brunswick, New Jersey 08901, United States.,Department of Chemistry and Chemical Biology, Rutgers University, 123 Bevier Road, Piscataway, New Jersey 08854, United States
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17
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Drake JL, Mass T, Stolarski J, Von Euw S, van de Schootbrugge B, Falkowski PG. How corals made rocks through the ages. Glob Chang Biol 2020; 26:31-53. [PMID: 31696576 PMCID: PMC6942544 DOI: 10.1111/gcb.14912] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Revised: 10/28/2019] [Accepted: 10/30/2019] [Indexed: 05/03/2023]
Abstract
Hard, or stony, corals make rocks that can, on geological time scales, lead to the formation of massive reefs in shallow tropical and subtropical seas. In both historical and contemporary oceans, reef-building corals retain information about the marine environment in their skeletons, which is an organic-inorganic composite material. The elemental and isotopic composition of their skeletons is frequently used to reconstruct the environmental history of Earth's oceans over time, including temperature, pH, and salinity. Interpretation of this information requires knowledge of how the organisms formed their skeletons. The basic mechanism of formation of calcium carbonate skeleton in stony corals has been studied for decades. While some researchers consider coral skeletons as mainly passive recorders of ocean conditions, it has become increasingly clear that biological processes play key roles in the biomineralization mechanism. Understanding the role of the animal in living stony coral biomineralization and how it evolved has profound implications for interpreting environmental signatures in fossil corals to understand past ocean conditions. Here we review historical hypotheses and discuss the present understanding of how corals evolved and how their skeletons changed over geological time. We specifically explain how biological processes, particularly those occurring at the subcellular level, critically control the formation of calcium carbonate structures. We examine the different models that address the current debate including the tissue-skeleton interface, skeletal organic matrix, and biomineralization pathways. Finally, we consider how understanding the biological control of coral biomineralization is critical to informing future models of coral vulnerability to inevitable global change, particularly increasing ocean acidification.
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Affiliation(s)
- Jeana L Drake
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, CA, USA
| | - Tali Mass
- Department of Marine Biology, The Leon H. Charney School of Marine Sciences, University of Haifa, Haifa, Israel
| | | | - Stanislas Von Euw
- Trinity Centre for Bioengineering, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin, Ireland
| | | | - Paul G Falkowski
- Department of Marine and Coastal Sciences, Rutgers University, New Brunswick, NJ, USA
- Department of Earth and Planetary Sciences, Rutgers University, New Brunswick, NJ, USA
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18
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Buck JM, Sherman J, Bártulos CR, Serif M, Halder M, Henkel J, Falciatore A, Lavaud J, Gorbunov MY, Kroth PG, Falkowski PG, Lepetit B. Lhcx proteins provide photoprotection via thermal dissipation of absorbed light in the diatom Phaeodactylum tricornutum. Nat Commun 2019; 10:4167. [PMID: 31519883 PMCID: PMC6744471 DOI: 10.1038/s41467-019-12043-6] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2019] [Accepted: 08/16/2019] [Indexed: 11/15/2022] Open
Abstract
Diatoms possess an impressive capacity for rapidly inducible thermal dissipation of excess absorbed energy (qE), provided by the xanthophyll diatoxanthin and Lhcx proteins. By knocking out the Lhcx1 and Lhcx2 genes individually in Phaeodactylum tricornutum strain 4 and complementing the knockout lines with different Lhcx proteins, multiple mutants with varying qE capacities are obtained, ranging from zero to high values. We demonstrate that qE is entirely dependent on the concerted action of diatoxanthin and Lhcx proteins, with Lhcx1, Lhcx2 and Lhcx3 having similar functions. Moreover, we establish a clear link between Lhcx1/2/3 mediated inducible thermal energy dissipation and a reduction in the functional absorption cross-section of photosystem II. This regulation of the functional absorption cross-section can be tuned by altered Lhcx protein expression in response to environmental conditions. Our results provide a holistic understanding of the rapidly inducible thermal energy dissipation process and its mechanistic implications in diatoms. Photosynthetic organisms can dissipate excess absorbed light energy as heat to avoid photodamage. Here the authors show that induced thermal dissipation in the diatom Phaeodactylum tricornutum Pt4 is Lhcx protein-dependent and correlates with a reduced functional absorption cross-section of photosystem II.
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Affiliation(s)
- Jochen M Buck
- Plant Ecophysiology, Department of Biology, University of Konstanz, 78457, Konstanz, Germany
| | - Jonathan Sherman
- Environmental Biophysics and Molecular Ecology Program, Department of Marine and Coastal Sciences, Rutgers, The State University of New Jersey, New Brunswick, NJ, 08901, USA
| | - Carolina Río Bártulos
- Plant Ecophysiology, Department of Biology, University of Konstanz, 78457, Konstanz, Germany
| | - Manuel Serif
- Plant Ecophysiology, Department of Biology, University of Konstanz, 78457, Konstanz, Germany
| | - Marc Halder
- Plant Ecophysiology, Department of Biology, University of Konstanz, 78457, Konstanz, Germany
| | - Jan Henkel
- Plant Ecophysiology, Department of Biology, University of Konstanz, 78457, Konstanz, Germany.,Institute of Genetics, Vetsuisse Faculty, University of Bern, 3001, Bern, Switzerland
| | - Angela Falciatore
- Sorbonne Université, Centre National de la Recherche Scientifique, Institut de Biologie Paris-Seine, Laboratory of Computational and Quantitative Biology, F-75005, Paris, France
| | - Johann Lavaud
- UMI 3376 Takuvik, CNRS/ULaval, Département de Biologie, Pavillon Alexandre-Vachon, Université Laval, Québec (Québec), G1V 0A6, Canada
| | - Maxim Y Gorbunov
- Environmental Biophysics and Molecular Ecology Program, Department of Marine and Coastal Sciences, Rutgers, The State University of New Jersey, New Brunswick, NJ, 08901, USA
| | - Peter G Kroth
- Plant Ecophysiology, Department of Biology, University of Konstanz, 78457, Konstanz, Germany
| | - Paul G Falkowski
- Environmental Biophysics and Molecular Ecology Program, Department of Marine and Coastal Sciences, Rutgers, The State University of New Jersey, New Brunswick, NJ, 08901, USA
| | - Bernard Lepetit
- Plant Ecophysiology, Department of Biology, University of Konstanz, 78457, Konstanz, Germany. .,Zukunftskolleg, University of Konstanz, 78457, Konstanz, Germany.
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19
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Kim JD, Pike DH, Tyryshkin AM, Swapna GVT, Raanan H, Montelione GT, Nanda V, Falkowski PG. Minimal Heterochiral de Novo Designed 4Fe-4S Binding Peptide Capable of Robust Electron Transfer. J Am Chem Soc 2018; 140:11210-11213. [PMID: 30141918 DOI: 10.1021/jacs.8b07553] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Ambidoxin is a designed, minimal dodecapeptide consisting of alternating L and D amino acids that binds a 4Fe-4S cluster through ligand-metal interactions and an extensive network of second-shell hydrogen bonds. The peptide can withstand hundreds of oxidation-reduction cycles at room temperature. Ambidoxin suggests how simple, prebiotic peptides may have achieved robust redox catalysis on the early Earth.
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Affiliation(s)
- J Dongun Kim
- Environmental Biophysics and Molecular Ecology Program, Department of Marine and Coastal Sciences, Rutgers , the State University of New Jersey , New Brunswick , New Jersey 08901 , United States
| | - Douglas H Pike
- Center for Advanced Biotechnology and Medicine , Rutgers, the State University of New Jersey , Piscataway , New Jersey 08854 , United States
| | - Alexei M Tyryshkin
- Environmental Biophysics and Molecular Ecology Program, Department of Marine and Coastal Sciences, Rutgers , the State University of New Jersey , New Brunswick , New Jersey 08901 , United States
| | - G V T Swapna
- Center for Advanced Biotechnology and Medicine , Rutgers, the State University of New Jersey , Piscataway , New Jersey 08854 , United States.,Department of Molecular Biology and Biochemistry, Rutgers , the State University of New Jersey , Piscataway , New Jersey 08854 , United States
| | - Hagai Raanan
- Environmental Biophysics and Molecular Ecology Program, Department of Marine and Coastal Sciences, Rutgers , the State University of New Jersey , New Brunswick , New Jersey 08901 , United States
| | - Gaetano T Montelione
- Center for Advanced Biotechnology and Medicine , Rutgers, the State University of New Jersey , Piscataway , New Jersey 08854 , United States.,Department of Molecular Biology and Biochemistry, Rutgers , the State University of New Jersey , Piscataway , New Jersey 08854 , United States.,Department of Biochemistry and Molecular Biology , Robert Wood Johnson Medical School, Rutgers, the State University of New Jersey , Piscataway , New Jersey 08854 , United States
| | - Vikas Nanda
- Center for Advanced Biotechnology and Medicine , Rutgers, the State University of New Jersey , Piscataway , New Jersey 08854 , United States.,Department of Biochemistry and Molecular Biology , Robert Wood Johnson Medical School, Rutgers, the State University of New Jersey , Piscataway , New Jersey 08854 , United States
| | - Paul G Falkowski
- Environmental Biophysics and Molecular Ecology Program, Department of Marine and Coastal Sciences, Rutgers , the State University of New Jersey , New Brunswick , New Jersey 08901 , United States.,Department of Earth and Planetary Sciences, Rutgers , the State University of New Jersey , Piscataway , New Jersey 08854 , United States
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20
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Jelen B, Giovannelli D, Falkowski PG, Vetriani C. Elemental sulfur reduction in the deep‐sea vent thermophile,
Thermovibrio ammonificans. Environ Microbiol 2018; 20:2301-2316. [DOI: 10.1111/1462-2920.14280] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2018] [Revised: 05/10/2018] [Accepted: 05/12/2018] [Indexed: 01/20/2023]
Affiliation(s)
- Benjamin Jelen
- Environmental Biophysics and Molecular Ecology Program Rutgers University, New Brunswick New Brunswick NJ 08901 USA
| | - Donato Giovannelli
- Department of Marine and Coastal Sciences Rutgers University New Brunswick NJ 08901 USA
- Institute of Marine Science National Research Council Ancona 60125 Italy
- Earth‐Life Science Institute Tokyo Institute of Technology Tokyo 152‐8550 Japan
| | - Paul G. Falkowski
- Environmental Biophysics and Molecular Ecology Program Rutgers University, New Brunswick New Brunswick NJ 08901 USA
- Department of Marine and Coastal Sciences Rutgers University New Brunswick NJ 08901 USA
- Department of Earth and Planetary Sciences Rutgers University New Brunswick NJ 08854 USA
| | - Costantino Vetriani
- Department of Marine and Coastal Sciences Rutgers University New Brunswick NJ 08901 USA
- Department of Biochemistry and Microbiology Rutgers University New Brunswick NJ 08901 USA
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21
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Falkowski PG. Reverse engineering nature. Environ Microbiol 2018; 20:1960-1961. [PMID: 29749687 DOI: 10.1111/1462-2920.14241] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Paul G Falkowski
- Environmental Biophysics and Molecular Ecology Program, Departments of Marine and Coastal Sciences and Earth and Planetary Sciences, Rutgers University, New Brunswick, NJ, 08540, USA
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22
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Falkowski PG, Lin H, Gorbunov MY. What limits photosynthetic energy conversion efficiency in nature? Lessons from the oceans. Philos Trans R Soc Lond B Biol Sci 2018; 372:rstb.2016.0376. [PMID: 28808095 DOI: 10.1098/rstb.2016.0376] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/23/2017] [Indexed: 11/12/2022] Open
Abstract
Constraining photosynthetic energy conversion efficiency in nature is challenging. In principle, two yield measurements must be made simultaneously: photochemistry, fluorescence and/or thermal dissipation. We constructed two different, extremely sensitive and precise active fluorometers: one measures the quantum yield of photochemistry from changes in variable fluorescence, the other measures fluorescence lifetimes in the picosecond time domain. By deploying the pair of instruments on eight transoceanic cruises over six years, we obtained over 200 000 measurements of fluorescence yields and lifetimes from surface waters in five ocean basins. Our results revealed that the average quantum yield of photochemistry was approximately 0.35 while the average quantum yield of fluorescence was approximately 0.07. Thus, closure on the energy budget suggests that, on average, approximately 58% of the photons absorbed by phytoplankton in the world oceans are dissipated as heat. This extraordinary inefficiency is associated with the paucity of nutrients in the upper ocean, especially dissolved inorganic nitrogen and iron. Our results strongly suggest that, in nature, most of the time, most of the phytoplankton community operates at approximately half of its maximal photosynthetic energy conversion efficiency because nutrients limit the synthesis or function of essential components in the photosynthetic apparatus.This article is part of the themed issue 'Enhancing photosynthesis in crop plants: targets for improvement'.
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Affiliation(s)
- Paul G Falkowski
- Environmental Biophysics and Molecular Ecology Program, Department of Marine and Coastal Sciences, Rutgers, the State University of New Jersey, New Brunswick, NJ 08901, USA .,Department of Earth and Planetary Sciences, Rutgers, the State University of New Jersey, Piscataway, NJ 08540, USA
| | - Hanzhi Lin
- Environmental Biophysics and Molecular Ecology Program, Department of Marine and Coastal Sciences, Rutgers, the State University of New Jersey, New Brunswick, NJ 08901, USA
| | - Maxim Y Gorbunov
- Environmental Biophysics and Molecular Ecology Program, Department of Marine and Coastal Sciences, Rutgers, the State University of New Jersey, New Brunswick, NJ 08901, USA
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23
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Abstract
Oxidoreductases catalyze electron transfer reactions that ultimately provide the energy for life. A limited set of ancestral protein-metal modules are presumably the building blocks that evolved into this diverse protein family. However, the identity of these modules and their path to modern oxidoreductases is unknown. Using a comparative structural analysis approach, we identify a set of fundamental electron transfer modules that have evolved to form the extant oxidoreductases. Using transition metal-containing cofactors as fiducial markers, it is possible to cluster cofactor microenvironments into as few as four major modules: bacterial ferredoxin, cytochrome c, symerythrin, and plastocyanin-type folds. From structural alignments, it is challenging to ascertain whether modules evolved from a single common ancestor (homology) or arose by independent convergence on a limited set of structural forms (analogy). Additional insight into common origins is contained in the spatial adjacency network (SPAN), which is based on proximity of modules in oxidoreductases containing multiple cofactor electron transfer chains. Electron transfer chains within complex modern oxidoreductases likely evolved through repeated duplication and diversification of ancient modular units that arose in the Archean eon.
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Affiliation(s)
- Hagai Raanan
- Environmental Biophysics and Molecular Ecology Program, Department of Marine and Coastal Sciences, Rutgers University, New Brunswick, NJ 08901
- Center for Advanced Biotechnology and Medicine, Rutgers University, Piscataway, NJ 08854
| | - Douglas H Pike
- Center for Advanced Biotechnology and Medicine, Rutgers University, Piscataway, NJ 08854
| | - Eli K Moore
- Environmental Biophysics and Molecular Ecology Program, Department of Marine and Coastal Sciences, Rutgers University, New Brunswick, NJ 08901
| | - Paul G Falkowski
- Environmental Biophysics and Molecular Ecology Program, Department of Marine and Coastal Sciences, Rutgers University, New Brunswick, NJ 08901;
- Department of Earth and Planetary Sciences, Rutgers University, New Brunswick, NJ 08901
| | - Vikas Nanda
- Center for Advanced Biotechnology and Medicine, Rutgers University, Piscataway, NJ 08854;
- Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, Rutgers University, Piscataway, NJ 08854
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24
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Mass T, Drake JL, Heddleston JM, Falkowski PG. Nanoscale Visualization of Biomineral Formation in Coral Proto-Polyps. Curr Biol 2017; 27:3191-3196.e3. [PMID: 29033329 DOI: 10.1016/j.cub.2017.09.012] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Revised: 07/11/2017] [Accepted: 09/06/2017] [Indexed: 11/16/2022]
Abstract
Calcium carbonate platforms produced by reef-building stony corals over geologic time are pervasive features around the world [1]; however, the mechanism by which these organisms produce the mineral is poorly understood (see review by [2]). It is generally assumed that stony corals precipitate calcium carbonate extracellularly as aragonite in a calcifying medium between the calicoblastic ectoderm and pre-existing skeleton, separated from the overlying seawater [2]. The calicoblastic ectoderm produces extracellular matrix (ECM) proteins, secreted to the calcifying medium [3-6], which appear to provide the nucleation, alteration, elongation, and inhibition mechanisms of the biomineral [7] and remain occluded and preserved in the skeleton [8-10]. Here we show in cell cultures of the stony coral Stylophora pistillata that calcium is concentrated in intracellular pockets that are subsequently exported from the cell where a nucleation process leads to the formation of extracellular aragonite crystals. Analysis of the growing crystals by lattice light-sheet microscopy suggests that the crystals elongate from the cells' surfaces outward.
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Affiliation(s)
- Tali Mass
- University of Haifa, Department of Marine Biology, The Leon H. Charney School of Marine Sciences, Multi Purpose Boulevard, Mt. Carmel, Haifa 3498838, Israel.
| | - Jeana L Drake
- Rutgers University, Department of Marine and Coastal Sciences, Dudley Road, New Brunswick, NJ 08901, USA
| | - John M Heddleston
- Howard Hughes Medical Institute Janelia Research Campus, Advanced Imaging Center, Helix Drive, Ashburn, VA 20147, USA
| | - Paul G Falkowski
- Rutgers University, Department of Marine and Coastal Sciences, Dudley Road, New Brunswick, NJ 08901, USA; Rutgers University, Department of Earth and Planetary Sciences, Taylor Road, Piscataway, NJ 08854, USA
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25
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Von Euw S, Zhang Q, Manichev V, Murali N, Gross J, Feldman LC, Gustafsson T, Flach C, Mendelsohn R, Falkowski PG. Biological control of aragonite formation in stony corals. Science 2017; 356:933-938. [DOI: 10.1126/science.aam6371] [Citation(s) in RCA: 124] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Accepted: 05/10/2017] [Indexed: 02/06/2023]
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26
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Putnam HM, Adams DK, Zelzion E, Wagner NE, Qiu H, Mass T, Falkowski PG, Gates RD, Bhattacharya D. Divergent evolutionary histories of DNA markers in a Hawaiian population of the coral Montipora capitata. PeerJ 2017; 5:e3319. [PMID: 28533967 PMCID: PMC5438590 DOI: 10.7717/peerj.3319] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2016] [Accepted: 04/15/2017] [Indexed: 11/20/2022] Open
Abstract
We investigated intra- and inter-colony sequence variation in a population of the dominant Hawaiian coral Montipora capitata by analyzing marker gene and genomic data. Ribosomal ITS1 regions showed evidence of a reticulate history among the colonies, suggesting incomplete rDNA repeat homogenization. Analysis of the mitochondrial genome identified a major (M. capitata) and a minor (M. flabellata) haplotype in single polyp-derived sperm bundle DNA with some colonies containing 2–3 different mtDNA haplotypes. In contrast, Pax-C and newly identified single-copy nuclear genes showed either no sequence differences or minor variations in SNP frequencies segregating among the colonies. Our data suggest past mitochondrial introgression in M. capitata, whereas nuclear single-copy loci show limited variation, highlighting the divergent evolutionary histories of these coral DNA markers.
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Affiliation(s)
- Hollie M Putnam
- Hawai'i Institute of Marine Biology, Kaneohe, HI, United States of America.,Department of Biological Sciences, University of Rhode Island, Kingston, RI, United States of America
| | - Diane K Adams
- Department of Marine and Coastal Sciences, Rutgers University, New Brunswick, NJ, United States of America
| | - Ehud Zelzion
- Department of Ecology, Evolution, and Natural Resources, Rutgers University, New Brunswick, NJ, United States of America
| | - Nicole E Wagner
- Department of Ecology, Evolution, and Natural Resources, Rutgers University, New Brunswick, NJ, United States of America
| | - Huan Qiu
- Department of Ecology, Evolution, and Natural Resources, Rutgers University, New Brunswick, NJ, United States of America
| | - Tali Mass
- Marine Biology Department, University of Haifa, Haifa, Israel
| | - Paul G Falkowski
- Department of Marine and Coastal Sciences, Rutgers University, New Brunswick, NJ, United States of America.,Department of Earth and Planetary Sciences, Rutgers University, Piscataway, NJ, United States of America
| | - Ruth D Gates
- Hawai'i Institute of Marine Biology, Kaneohe, HI, United States of America
| | - Debashish Bhattacharya
- Department of Ecology, Evolution, and Natural Resources, Rutgers University, New Brunswick, NJ, United States of America
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27
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Dinamarca J, Levitan O, Kumaraswamy GK, Lun DS, Falkowski PG. Overexpression of a diacylglycerol acyltransferase gene in Phaeodactylum tricornutum directs carbon towards lipid biosynthesis. J Phycol 2017; 53:405-414. [PMID: 28078675 DOI: 10.1111/jpy.12513] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2016] [Accepted: 11/17/2016] [Indexed: 05/03/2023]
Abstract
Under nutrient deplete conditions, diatoms accumulate between 15% to 25% of their dry weight as lipids, primarily as triacylglycerols (TAGs). As in most eukaryotes, these organisms produce TAGs via the acyl-CoA dependent Kennedy pathway. The last step in this pathway is catalyzed by diacylglycerol acyltransferase (DGAT) that acylates diacylglycerol (DAG) to produce TAG. To test our hypothesis that DGAT plays a major role in controlling the flux of carbon towards lipids, we overexpressed a specific type II DGAT gene, DGAT2D, in the model diatom Phaeodactylum tricornutum. The transformants had 50- to 100-fold higher DGAT2D mRNA levels and the abundance of the enzyme increased 30- to 50-fold. More important, these cells had a 2-fold higher total lipid content and incorporated carbon into lipids more efficiently than the wild type (WT) while growing only 15% slower at light saturation. Based on a flux analysis using 13 C as a tracer, we found that the increase in lipids was achieved via increased fluxes through pyruvate and acetyl-CoA. Our results reveal overexpression of DAGT2D increases the flux of photosynthetically fixed carbon towards lipids, and leads to a higher lipid content than exponentially grown WT cells.
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Affiliation(s)
- Jorge Dinamarca
- Environmental Biophysics and Molecular Ecology Laboratory, Department of Marine and Coastal Sciences, Rutgers University, New Brunswick, New Jersey, 08901, USA
| | - Orly Levitan
- Environmental Biophysics and Molecular Ecology Laboratory, Departments of Marine and Coastal Sciences and Plant Biology and Pathology, Rutgers University, New Brunswick, New Jersey, 08901, USA
| | - G Kenchappa Kumaraswamy
- Waksman Institute and Department of Chemistry & Chemical Biology, Rutgers University, Piscataway, New Jersey, 08854, USA
| | - Desmond S Lun
- Center for Computational and Integrative Biology and Department of Computer Science, Rutgers University, Camden, New Jersey, 08102, USA
- Department of Plant Biology, Rutgers University, New Brunswick, New Jersey, 08901, USA
| | - Paul G Falkowski
- Environmental Biophysics and Molecular Ecology Laboratory, Departments of Marine and Coastal Sciences and Earth and Planetary Sciences, Rutgers University, Piscataway, New Jersey, 0885, USA
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28
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Mass T, Putnam HM, Drake JL, Zelzion E, Gates RD, Bhattacharya D, Falkowski PG. Temporal and spatial expression patterns of biomineralization proteins during early development in the stony coral Pocillopora damicornis. Proc Biol Sci 2017; 283:rspb.2016.0322. [PMID: 27122561 DOI: 10.1098/rspb.2016.0322] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2016] [Accepted: 04/01/2016] [Indexed: 11/12/2022] Open
Abstract
Reef-building corals begin as non-calcifying larvae that, upon settling, rapidly begin to accrete skeleton and a protein-rich skeletal organic matrix that attach them to the reef. Here, we characterized the temporal and spatial expression pattern of a suite of biomineralization genes during three stages of larval development in the reef-building coral Pocillopora damicornis: stage I, newly released; stage II, oral-aborally compressed and stage III, settled and calcifying spat. Transcriptome analysis revealed 3882 differentially expressed genes that clustered into four distinctly different patterns of expression change across the three developmental stages. Immunolocalization analysis further reveals the spatial arrangement of coral acid-rich proteins (CARPs) in the overall architecture of the emerging skeleton. These results provide the first analysis of the timing of the biomineralization 'toolkit' in the early life history of a stony coral.
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Affiliation(s)
- Tali Mass
- Environmental Biophysics and Molecular Ecology Program, Department of Marine and Coastal Sciences, Kaneohe, HI 96744, USA
| | | | - Jeana L Drake
- Environmental Biophysics and Molecular Ecology Program, Department of Marine and Coastal Sciences, Kaneohe, HI 96744, USA
| | - Ehud Zelzion
- Department of Ecology, Evolution and Natural Resources, Rutgers University, New Brunswick, NJ 08901, USA
| | - Ruth D Gates
- Hawaii Institute of Marine Biology, Kaneohe, HI 96744, USA
| | - Debashish Bhattacharya
- Department of Ecology, Evolution and Natural Resources, Rutgers University, New Brunswick, NJ 08901, USA Department of Marine and Coastal Sciences, Rutgers University, New Brunswick, NJ 08901, USA
| | - Paul G Falkowski
- Environmental Biophysics and Molecular Ecology Program, Department of Marine and Coastal Sciences, Kaneohe, HI 96744, USA Department of Earth and Planetary Sciences, Rutgers University, Piscataway, NJ 08854, USA
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29
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Harel A, Häggblom MM, Falkowski PG, Yee N. Evolution of prokaryotic respiratory molybdoenzymes and the frequency of their genomic co-occurrence. FEMS Microbiol Ecol 2016; 92:fiw187. [DOI: 10.1093/femsec/fiw187] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/05/2016] [Indexed: 02/03/2023] Open
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30
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Abstract
All life on Earth is dependent on biologically mediated electron transfer (i.e., redox) reactions that are far from thermodynamic equilibrium. Biological redox reactions originally evolved in prokaryotes and ultimately, over the first ∼2.5 billion years of Earth's history, formed a global electronic circuit. To maintain the circuit on a global scale requires that oxidants and reductants be transported; the two major planetary wires that connect global metabolism are geophysical fluids-the atmosphere and the oceans. Because all organisms exchange gases with the environment, the evolution of redox reactions has been a major force in modifying the chemistry at Earth's surface. Here we briefly review the discovery and consequences of redox reactions in microbes with a specific focus on the coevolution of life and geochemical phenomena.
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Affiliation(s)
- Benjamin I Jelen
- Environmental Biophysics and Molecular Ecology Program, Institute of Earth, Ocean and Atmospheric Sciences, Rutgers University, New Brunswick, New Jersey 08901; , ,
| | - Donato Giovannelli
- Environmental Biophysics and Molecular Ecology Program, Institute of Earth, Ocean and Atmospheric Sciences, Rutgers University, New Brunswick, New Jersey 08901; , , .,Institute of Marine Science, National Research Council, 60125 Ancona, Italy.,Program in Interdisciplinary Studies, Institute for Advanced Studies, Princeton, New Jersey 08540.,Earth-Life Science Institute, Tokyo Institute of Technology, Tokyo, Japan 152-8550
| | - Paul G Falkowski
- Environmental Biophysics and Molecular Ecology Program, Institute of Earth, Ocean and Atmospheric Sciences, Rutgers University, New Brunswick, New Jersey 08901; , , .,Department of Earth and Planetary Sciences, Rutgers University, New Brunswick, New Jersey 08854
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31
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Bhattacharya D, Agrawal S, Aranda M, Baumgarten S, Belcaid M, Drake JL, Erwin D, Foret S, Gates RD, Gruber DF, Kamel B, Lesser MP, Levy O, Liew YJ, MacManes M, Mass T, Medina M, Mehr S, Meyer E, Price DC, Putnam HM, Qiu H, Shinzato C, Shoguchi E, Stokes AJ, Tambutté S, Tchernov D, Voolstra CR, Wagner N, Walker CW, Weber AP, Weis V, Zelzion E, Zoccola D, Falkowski PG. Comparative genomics explains the evolutionary success of reef-forming corals. eLife 2016; 5. [PMID: 27218454 PMCID: PMC4878875 DOI: 10.7554/elife.13288] [Citation(s) in RCA: 118] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2015] [Accepted: 04/20/2016] [Indexed: 12/30/2022] Open
Abstract
Transcriptome and genome data from twenty stony coral species and a selection of reference bilaterians were studied to elucidate coral evolutionary history. We identified genes that encode the proteins responsible for the precipitation and aggregation of the aragonite skeleton on which the organisms live, and revealed a network of environmental sensors that coordinate responses of the host animals to temperature, light, and pH. Furthermore, we describe a variety of stress-related pathways, including apoptotic pathways that allow the host animals to detoxify reactive oxygen and nitrogen species that are generated by their intracellular photosynthetic symbionts, and determine the fate of corals under environmental stress. Some of these genes arose through horizontal gene transfer and comprise at least 0.2% of the animal gene inventory. Our analysis elucidates the evolutionary strategies that have allowed symbiotic corals to adapt and thrive for hundreds of millions of years. DOI:http://dx.doi.org/10.7554/eLife.13288.001 For millions of years, reef-building stony corals have created extensive habitats for numerous marine plants and animals in shallow tropical seas. Stony corals consist of many small, tentacled animals called polyps. These polyps secrete a mineral called aragonite to create the reef – an external ‘skeleton’ that supports and protects the corals. Photosynthesizing algae live inside the cells of stony corals, and each species depends on the other to survive. The algae produce the coral’s main source of food, although they also produce some waste products that can harm the coral if they build up inside cells. If the oceans become warmer and more acidic, the coral are more likely to become stressed and expel the algae from their cells in a process known as coral bleaching. This makes the coral more likely to die or become diseased. Corals have survived previous periods of ocean warming, although it is not known how they evolved to do so. The evolutionary history of an organism can be traced by studying its genome – its complete set of DNA – and the RNA molecules encoded by these genes. Bhattacharya et al. performed this analysis for twenty stony coral species, and compared the resulting genome and RNA sequences with the genomes of other related marine organisms, such as sea anemones and sponges. In particular, Bhattacharya et al. examined “ortholog” groups of genes, which are present in different species and evolved from a common ancestral gene. This analysis identified the genes in the corals that encode the proteins responsible for constructing the aragonite skeleton. The coral genome also encodes a network of environmental sensors that coordinate how the polyps respond to temperature, light and acidity. Bhattacharya et al. also uncovered a variety of stress-related pathways, including those that detoxify the polyps of the damaging molecules generated by algae, and the pathways that enable the polyps to adapt to environmental stress. Many of these genes were recruited from other species in a process known as horizontal gene transfer. The oceans are expected to become warmer and more acidic in the coming centuries. Provided that humans do not physically destroy the corals’ habitats, the evidence found by Bhattacharya et al. suggests that the genome of the corals contains the diversity that will allow them to adapt to these new conditions. DOI:http://dx.doi.org/10.7554/eLife.13288.002
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Affiliation(s)
- Debashish Bhattacharya
- Department of Ecology, Evolution and Natural Resources, Rutgers University, New Brunswick, United States.,Department of Marine and Coastal Sciences, Rutgers University, New Brunswick, United States
| | - Shobhit Agrawal
- Red Sea Research Center, Biological and Environmental Sciences and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia
| | - Manuel Aranda
- Red Sea Research Center, Biological and Environmental Sciences and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia
| | - Sebastian Baumgarten
- Red Sea Research Center, Biological and Environmental Sciences and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia
| | - Mahdi Belcaid
- Hawaii Institute of Marine Biology, Kaneohe, United States
| | - Jeana L Drake
- Environmental Biophysics and Molecular Ecology Program, Department of Marine and Coastal Sciences, Rutgers University, New Brunswick, United States
| | - Douglas Erwin
- Smithsonian Institution, National Museum of Natural History, Washington, United States
| | - Sylvian Foret
- ARC Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, Australia.,Research School of Biology, Australian National University, Canberra, Australia
| | - Ruth D Gates
- Hawaii Institute of Marine Biology, Kaneohe, United States
| | - David F Gruber
- American Museum of Natural History, Sackler Institute for Comparative Genomics, New York, United States.,Department of Natural Sciences, City University of New York, Baruch College and The Graduate Center, New York, United States
| | - Bishoy Kamel
- Department of Biology, Mueller Lab, Penn State University, University Park, United States
| | - Michael P Lesser
- School of Marine Science and Ocean Engineering, University of New Hampshire, Durham, United States
| | - Oren Levy
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gam, Israel
| | - Yi Jin Liew
- Red Sea Research Center, Biological and Environmental Sciences and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia
| | - Matthew MacManes
- Department of Molecular, Cellular and Biomedical Sciences, University of New Hampshire, Durham, United States
| | - Tali Mass
- Environmental Biophysics and Molecular Ecology Program, Department of Marine and Coastal Sciences, Rutgers University, New Brunswick, United States.,Marine Biology Department, The Leon H. Charney School of Marine Sciences, University of Haifa, Mt. Carmel, Israel
| | - Monica Medina
- Department of Biology, Mueller Lab, Penn State University, University Park, United States
| | - Shaadi Mehr
- American Museum of Natural History, Sackler Institute for Comparative Genomics, New York, United States.,Biological Science Department, State University of New York, College at Old Westbury, New York, United States
| | - Eli Meyer
- Department of Integrative Biology, Oregon State University, Corvallis, United States
| | - Dana C Price
- Department of Plant Biology and Pathology, Rutgers University, New Brunswick, United States
| | | | - Huan Qiu
- Department of Ecology, Evolution and Natural Resources, Rutgers University, New Brunswick, United States
| | - Chuya Shinzato
- Marine Genomics Unit, Okinawa Institute of Science and Technology Graduate University, Okinawa, Japan
| | - Eiichi Shoguchi
- Marine Genomics Unit, Okinawa Institute of Science and Technology Graduate University, Okinawa, Japan
| | - Alexander J Stokes
- Laboratory of Experimental Medicine and Department of Cell and Molecular Biology, John A. Burns School of Medicine, Honolulu, United States.,Chaminade University, Honolulu, United States
| | | | - Dan Tchernov
- Marine Biology Department, The Leon H. Charney School of Marine Sciences, University of Haifa, Mt. Carmel, Israel
| | - Christian R Voolstra
- Red Sea Research Center, Biological and Environmental Sciences and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia
| | - Nicole Wagner
- Department of Ecology, Evolution and Natural Resources, Rutgers University, New Brunswick, United States
| | - Charles W Walker
- Department of Molecular, Cellular and Biomedical Sciences, University of New Hampshire, Durham, United States
| | - Andreas Pm Weber
- Institute of Plant Biochemistry, Heinrich-Heine-Universität, Düsseldorf, Germany
| | - Virginia Weis
- Department of Integrative Biology, Oregon State University, Corvallis, United States
| | - Ehud Zelzion
- Department of Ecology, Evolution and Natural Resources, Rutgers University, New Brunswick, United States
| | | | - Paul G Falkowski
- Environmental Biophysics and Molecular Ecology Program, Department of Marine and Coastal Sciences, Rutgers University, New Brunswick, United States.,Department of Earth and Planetary Sciences, Rutgers University, New Jersey, United States
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32
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Lin H, Kuzminov FI, Park J, Lee S, Falkowski PG, Gorbunov MY. The fate of photons absorbed by phytoplankton in the global ocean. Science 2016; 351:264-7. [DOI: 10.1126/science.aab2213] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2015] [Accepted: 12/09/2015] [Indexed: 11/03/2022]
Affiliation(s)
- Hanzhi Lin
- Environmental Biophysics and Molecular Ecology Program, Department of Marine and Coastal Sciences, Rutgers, The State University of New Jersey, 71 Dudley Road, New Brunswick, NJ, USA
| | - Fedor I. Kuzminov
- Environmental Biophysics and Molecular Ecology Program, Department of Marine and Coastal Sciences, Rutgers, The State University of New Jersey, 71 Dudley Road, New Brunswick, NJ, USA
| | - Jisoo Park
- Korea Polar Research Institute, 26 Songdomirae-ro, Yeonsu-Gu, Incheon, Republic of Korea
| | - SangHoon Lee
- Korea Polar Research Institute, 26 Songdomirae-ro, Yeonsu-Gu, Incheon, Republic of Korea
| | - Paul G. Falkowski
- Environmental Biophysics and Molecular Ecology Program, Department of Marine and Coastal Sciences, Rutgers, The State University of New Jersey, 71 Dudley Road, New Brunswick, NJ, USA
- Department of Earth and Planetary Sciences, Rutgers, The State University of New Jersey, Piscataway, NJ, USA
| | - Maxim Y. Gorbunov
- Environmental Biophysics and Molecular Ecology Program, Department of Marine and Coastal Sciences, Rutgers, The State University of New Jersey, 71 Dudley Road, New Brunswick, NJ, USA
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33
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Kim J, Fabris M, Baart G, Kim MK, Goossens A, Vyverman W, Falkowski PG, Lun DS. Flux balance analysis of primary metabolism in the diatom Phaeodactylum tricornutum. Plant J 2016; 85:161-176. [PMID: 26590126 DOI: 10.1111/tpj.13081] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2014] [Revised: 11/04/2015] [Accepted: 11/09/2015] [Indexed: 06/05/2023]
Abstract
Diatoms (Bacillarophyceae) are photosynthetic unicellular microalgae that have risen to ecological prominence in oceans over the past 30 million years. They are of interest as potential feedstocks for sustainable biofuels. Maximizing production of these feedstocks will require genetic modifications and an understanding of algal metabolism. These processes may benefit from genome-scale models, which predict intracellular fluxes and theoretical yields, as well as the viability of knockout and knock-in transformants. Here we present a genome-scale metabolic model of a fully sequenced and transformable diatom: Phaeodactylum tricornutum. The metabolic network was constructed using the P. tricornutum genome, biochemical literature, and online bioinformatic databases. Intracellular fluxes in P. tricornutum were calculated for autotrophic, mixotrophic and heterotrophic growth conditions, as well as knockout conditions that explore the in silico role of glycolytic enzymes in the mitochondrion. The flux distribution for lower glycolysis in the mitochondrion depended on which transporters for TCA cycle metabolites were included in the model. The growth rate predictions were validated against experimental data obtained using chemostats. Two published studies on this organism were used to validate model predictions for cyclic electron flow under autotrophic conditions, and fluxes through the phosphoketolase, glycine and serine synthesis pathways under mixotrophic conditions. Several gaps in annotation were also identified. The model also explored unusual features of diatom metabolism, such as the presence of lower glycolysis pathways in the mitochondrion, as well as differences between P. tricornutum and other photosynthetic organisms.
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Affiliation(s)
- Joomi Kim
- Environmental Biophysics and Molecular Ecology Program, Department of Marine and Coastal Sciences, Rutgers University, New Brunswick, NJ, 08901, USA
| | - Michele Fabris
- Plant Functional Biology and Climate Change Cluster (C3), Faculty of Science University of Technology, Sydney, New South Wales, Australia
- Department of Plant Systems Biology, Vlaams Instituut voor Biotechnologie, B-9052, Gent, Belgium
- Department of Plant Biotechnology and Bioinformatics, Ghent University, B-9052, Gent, Belgium
- Department of Biology, Laboratory of Protistology and Aquatic Ecology, Ghent University, B-9000, Gent, Belgium
| | - Gino Baart
- Department of Plant Systems Biology, Vlaams Instituut voor Biotechnologie, B-9052, Gent, Belgium
- Department of Plant Biotechnology and Bioinformatics, Ghent University, B-9052, Gent, Belgium
- Department of Biology, Laboratory of Protistology and Aquatic Ecology, Ghent University, B-9000, Gent, Belgium
- Centre of Microbial and Plant Genetics Lab for Genetics and Genomics and Leuven Institute for Beer Research, Leuven University, Gaston Geenslaan 1, B-3001, Leuven, Belgium
| | - Min K Kim
- Center for Computational and Integrative Biology and Department of Computer Science, Rutgers University, Camden, NJ, 08102, USA
| | - Alain Goossens
- Department of Plant Systems Biology, Vlaams Instituut voor Biotechnologie, B-9052, Gent, Belgium
- Department of Plant Biotechnology and Bioinformatics, Ghent University, B-9052, Gent, Belgium
| | - Wim Vyverman
- Department of Biology, Laboratory of Protistology and Aquatic Ecology, Ghent University, B-9000, Gent, Belgium
| | - Paul G Falkowski
- Environmental Biophysics and Molecular Ecology Program, Department of Marine and Coastal Sciences, Rutgers University, New Brunswick, NJ, 08901, USA
| | - Desmond S Lun
- Center for Computational and Integrative Biology and Department of Computer Science, Rutgers University, Camden, NJ, 08102, USA
- Department of Plant Biology and Pathology, Rutgers University, New Brunswick, NJ, 08901, USA
- School of Information Technology and Mathematical Sciences, University of South Australia, Mawson Lakes, South Australia, Australia
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34
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Levitan O, Dinamarca J, Zelzion E, Gorbunov MY, Falkowski PG. An RNA interference knock-down of nitrate reductase enhances lipid biosynthesis in the diatom Phaeodactylum tricornutum. Plant J 2015; 84:963-973. [PMID: 26473332 DOI: 10.1111/tpj.13052] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2015] [Revised: 09/29/2015] [Accepted: 10/07/2015] [Indexed: 06/05/2023]
Abstract
When diatoms are stressed for inorganic nitrogen they remodel their intermediate metabolism and redirect carbon towards lipid biosynthesis. However, this response comes at a significant cost reflected in decreased photosynthetic energy conversion efficiency and growth. Here we explore a molecular genetics approach to restrict the assimilation of inorganic nitrogen by knocking down nitrate reductase (NR). The transformant strain, NR21, exhibited about 50% lower expression and activity of the enzyme but simultaneously accumulated over 40% more fatty acids. However, in contrast to nitrogen-stressed wild-type (WT) cells, which grow at about 20% of the rate of nitrogen-replete cells, growth of NR21 was only reduced by about 30%. Biophysical analyses revealed that the photosynthetic energy conversion efficiency of photosystem II was unaffected in NR21; nevertheless, the plastoquinone pool was reduced by 50% at the optimal growth irradiance while in the WT it was over 90% oxidized. Further analyses reveal a 12-fold increase in the glutamate/glutamine ratio and an increase NADPH and malonyl-CoA pool size. Transcriptomic analyses indicate that the knock down resulted in changes in the expression of genes for lipid biosynthesis, as well as the expression of specific transcription factors. Based on these observations, we hypothesize that the allocation of carbon and reductants in diatoms is controlled by a feedback mechanism between intermediate metabolites, the redox state of the plastid and the expression and binding of transcription factors related to stress responses.
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Affiliation(s)
- Orly Levitan
- Environmental Biophysics and Molecular Ecology Program, Department of Marine and Coastal Sciences, Rutgers University, New Brunswick, NJ, 08901, USA
| | - Jorge Dinamarca
- Environmental Biophysics and Molecular Ecology Program, Department of Marine and Coastal Sciences, Rutgers University, New Brunswick, NJ, 08901, USA
| | - Ehud Zelzion
- Department of Ecology, Evolution and Natural Resources, Rutgers University, New Brunswick, NJ, 09801, USA
| | - Maxim Y Gorbunov
- Environmental Biophysics and Molecular Ecology Program, Department of Marine and Coastal Sciences, Rutgers University, New Brunswick, NJ, 08901, USA
| | - Paul G Falkowski
- Environmental Biophysics and Molecular Ecology Program, Department of Marine and Coastal Sciences, Rutgers University, New Brunswick, NJ, 08901, USA
- Department of Earth and Planetary Sciences, Rutgers University, Piscataway, NJ, 08854, USA
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35
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Abstract
The biogeochemical cycles of H, C, N, O and S are coupled via biologically catalyzed electron transfer (redox) reactions far from thermodynamic equilibrium. In this paper I examine the evolution of the structural motifs responsible for redox reactions (the biological "transistors") across the tree of life, and the photogeochemical reactions on minerals that ultimately came to be the driving force for these biological reactions.
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Affiliation(s)
- Paul G Falkowski
- Environmental Biophysics and Molecular Ecology Program, Department of Earth and Planetary Sciences and Department of Marine and Coastal Sciences, Rutgers University, New Brunswick, NJ, USA,
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36
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Abstract
Long-term global climate change, caused by burning petroleum and other fossil fuels, has motivated an urgent need to develop renewable, carbon-neutral, economically viable alternatives to displace petroleum using existing infrastructure. Algal feedstocks are promising candidate replacements as a 'drop-in' fuel. Here, we focus on a specific algal taxon, diatoms, to become the fossil fuel of the future. We summarize past attempts to obtain suitable diatom strains, propose future directions for their genetic manipulation, and offer biotechnological pathways to improve yield. We calculate that the yields obtained by using diatoms as a production platform are theoretically sufficient to satisfy the total oil consumption of the US, using between 3 and 5% of its land area.
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Affiliation(s)
- Orly Levitan
- Environmental Biophysics and Molecular Ecology Program, Institute of Marine and Coastal Sciences, Rutgers University, New Brunswick, NJ 08901, USA.
| | - Jorge Dinamarca
- Environmental Biophysics and Molecular Ecology Program, Institute of Marine and Coastal Sciences, Rutgers University, New Brunswick, NJ 08901, USA.
| | - Gal Hochman
- Department of Agriculture, Food & Resource Economics, Rutgers University, New Brunswick, NJ 08901, USA
| | - Paul G Falkowski
- Environmental Biophysics and Molecular Ecology Program, Institute of Marine and Coastal Sciences, Rutgers University, New Brunswick, NJ 08901, USA; Department of Earth and Planetary Sciences, Rutgers University, Piscataway, NJ 0885, USA
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37
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Harrold JW, Woronowicz K, Lamptey JL, Awong J, Baird J, Moshar A, Vittadello M, Falkowski PG, Niederman RA. Functional Interfacing of Rhodospirillum rubrum Chromatophores to a Conducting Support for Capture and Conversion of Solar Energy. J Phys Chem B 2013; 117:11249-59. [DOI: 10.1021/jp402108s] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- John W. Harrold
- Department of Chemistry and Chemical
Biology, Rutgers, The State University of New Jersey, 610 Taylor Road, Piscataway, New Jersey
08854, United States
| | - Kamil Woronowicz
- Department of Molecular Biology and Biochemistry, Rutgers, The State University of New Jersey, 604 Allison
Road, Piscataway, New Jersey 08854-8082, United States
| | - Joana L. Lamptey
- Department of Molecular Biology and Biochemistry, Rutgers, The State University of New Jersey, 604 Allison
Road, Piscataway, New Jersey 08854-8082, United States
| | - John Awong
- Energy Nanotechnology and Materials
Chemistry Lab, Medgar Evers College of the City University of New York, 1638 Bedford Avenue, Brooklyn, New York 11225, United States
| | - James Baird
- Energy Nanotechnology and Materials
Chemistry Lab, Medgar Evers College of the City University of New York, 1638 Bedford Avenue, Brooklyn, New York 11225, United States
| | - Amir Moshar
- Asylum Research, 6310 Hollister Avenue, Santa Barbara, California 93117, United
States
| | - Michele Vittadello
- Energy Nanotechnology and Materials
Chemistry Lab, Medgar Evers College of the City University of New York, 1638 Bedford Avenue, Brooklyn, New York 11225, United States
| | - Paul G. Falkowski
- Department of Chemistry and Chemical
Biology, Rutgers, The State University of New Jersey, 610 Taylor Road, Piscataway, New Jersey
08854, United States
- Institute for Marine
and Coastal Sciences, Rutgers, The State University of New Jersey, 71 Dudley Road, New Brunswick, New Jersey
08901, United States
| | - Robert A. Niederman
- Department of Molecular Biology and Biochemistry, Rutgers, The State University of New Jersey, 604 Allison
Road, Piscataway, New Jersey 08854-8082, United States
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38
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Abstract
Photochemical reactions of minerals are underappreciated processes that can make or break chemical bonds. We report the photooxidation of siderite (FeCO3) by UV radiation to produce hydrogen gas and iron oxides via a two-photon reaction. The calculated quantum yield for the reaction suggests photooxidation of siderite would have been a significant source of molecular hydrogen for the first half of Earth's history. Further, experimental results indicate this abiotic, photochemical process may have led to the formation of iron oxides under anoxic conditions. The reaction would have continued through the Archean to at least the early phases of the Great Oxidation Event, and provided a mechanism for oxidizing the atmosphere through the loss of hydrogen to space, while simultaneously providing a key reductant for microbial metabolism. We propose that the photochemistry of Earth-abundant minerals with wide band gaps would have potentially played a critical role in shaping the biogeochemical evolution of early Earth.
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Affiliation(s)
| | - Nathan Yee
- Environmental Sciences, and
- Earth and Planetary Sciences, Rutgers University, Piscataway, NJ 08854
| | - Vikas Nanda
- Department of Biochemistry, Robert Wood Johnson Medical School, University of Medicine and Dentistry of New Jersey, Piscataway, NJ 08854; and
| | - Paul G. Falkowski
- Departments of Chemistry and Chemical Biology
- Environmental Sciences, and
- Earth and Planetary Sciences, Rutgers University, Piscataway, NJ 08854
- Institute of Marine and Coastal Sciences, Rutgers University, New Brunswick, NJ 08901
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Kim JD, Senn S, Harel A, Jelen BI, Falkowski PG. Discovering the electronic circuit diagram of life: structural relationships among transition metal binding sites in oxidoreductases. Philos Trans R Soc Lond B Biol Sci 2013; 368:20120257. [PMID: 23754810 DOI: 10.1098/rstb.2012.0257] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Oxidoreductases play a central role in catalysing enzymatic electron-transfer reactions across the tree of life. To first order, the equilibrium thermodynamic properties of these proteins are governed by protein folds associated with specific transition metals and ligands at the active site. A global analysis of holoenzyme structures and functions suggests that there are fewer than approximately 500 fundamental oxidoreductases, which can be further clustered into 35 unique groups. These catalysts evolved in prokaryotes early in the Earth's history and are largely responsible for the emergence of non-equilibrium biogeochemical cycles on the planet's surface. Although the evolutionary history of the amino acid sequences in the oxidoreductases is very difficult to reconstruct due to gene duplication and horizontal gene transfer, the evolution of the folds in the catalytic sites can potentially be used to infer the history of these enzymes. Using a novel, yet simple analysis of the secondary structures associated with the ligands in oxidoreductases, we developed a structural phylogeny of these enzymes. The results of this 'composome' analysis suggest an early split from a basal set of a small group of proteins dominated by loop structures into two families of oxidoreductases, one dominated by α-helices and the second by β-sheets. The structural evolutionary patterns in both clades trace redox gradients and increased hydrogen bond energy in the active sites. The overall pattern suggests that the evolution of the oxidoreductases led to decreased entropy in the transition metal folds over approximately 2.5 billion years, allowing the enzymes to use increasingly oxidized substrates with high specificity.
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Affiliation(s)
- J Dongun Kim
- Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, NJ 08854, USA
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Frada MJ, Burrows EH, Wyman KD, Falkowski PG. Quantum requirements for growth and fatty acid biosynthesis in the marine diatom Phaeodactylum tricornutum (Bacillariophyceae) in nitrogen replete and limited conditions. J Phycol 2013; 49:381-388. [PMID: 27008524 DOI: 10.1111/jpy.12046] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2012] [Accepted: 12/15/2012] [Indexed: 06/05/2023]
Abstract
We determined the quantum requirements for growth (1/ϕμ ) and fatty acid (FA) biosynthesis (1/ϕFA ) in the marine diatom, Phaeodactylum tricornutum, grown in nutrient replete conditions with nitrate or ammonium as nitrogen sources, and under nitrogen limitation, achieved by transferring cells into nitrogen free medium or by inhibiting nitrate assimilation with tungstate. A treatment in which tungstate was supplemented to cells grown with ammonium was also included. In nutrient replete conditions, cells grew exponentially and possessed virtually identical 1/ϕμ of 40-44 mol photons · mol C(-1) . In parallel, 1/ϕFA varied between 380 and 409 mol photons · mol C(-1) in the presence of nitrate, but declined to 348 mol photons · mol C(-1) with ammonium and to 250 mol photons · mol C(-1) with ammonium plus tungstate, indicating an increase in the efficiency of FA biosynthesis relative to cells grown on nitrate of 8% and 35%, respectively. While the molecular mechanism for this effect remains poorly understood, the results unambiguously reveal that cells grown on ammonium are able to direct more reductant to lipids. This analysis suggests that when cells are grown with a reduced nitrogen source, fatty acid biosynthesis can effectively become a sink for excess absorbed light, compensating for the absence of energetically demanding nitrate assimilation reactions. Our data further suggest that optimal lipid production efficiency is achieved when cells are in exponential growth, when nitrate assimilation is inhibited, and ammonium is the sole nitrogen source.
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Affiliation(s)
- Miguel J Frada
- Environmental Biophysics and Molecular Ecology Program, Institute of Marine and Coastal Sciences, Rutgers University, 71 Dudley Road, New Brunswick, New Jersey, 08901, USA
| | - Elizabeth H Burrows
- Department of Chemistry & Chemical Biology, Rutgers University, 610 Taylor Rd., Piscataway, New Jersey, 08854, USA
| | - Kevin D Wyman
- Environmental Biophysics and Molecular Ecology Program, Institute of Marine and Coastal Sciences, Rutgers University, 71 Dudley Road, New Brunswick, New Jersey, 08901, USA
| | - Paul G Falkowski
- Environmental Biophysics and Molecular Ecology Program, Institute of Marine and Coastal Sciences, Rutgers University, 71 Dudley Road, New Brunswick, New Jersey, 08901, USA
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41
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Affiliation(s)
- Richard A Lutz
- Institute of Marine and Coastal Sciences, Rutgers University, New Brunswick, NJ 08901, USA.
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42
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Abstract
Models of early protein evolution posit the existence of short peptides that bound metals and ions and served as transporters, membranes or catalysts. The Cys-X-X-Cys-X-X-Cys heptapeptide located within bacterial ferredoxins, enclosing an Fe4S4 metal center, is an attractive candidate for such an early peptide. Ferredoxins are ancient proteins and the simple α+β fold is found alone or as a domain in larger proteins throughout all three kingdoms of life. Previous analyses of the heptapeptide conformation in experimentally determined ferredoxin structures revealed a pervasive right-handed topology, despite the fact that the Fe4S4 cluster is achiral. Conformational enumeration of a model CGGCGGC heptapeptide bound to a cubane iron-sulfur cluster indicates both left-handed and right-handed folds could exist and have comparable stabilities. However, only the natural ferredoxin topology provides a significant network of backbone-to-cluster hydrogen bonds that would stabilize the metal-peptide complex. The optimal peptide configuration (alternating αL,αR) is that of an α-sheet, providing an additional mechanism where oligomerization could stabilize the peptide and facilitate iron-sulfur cluster binding. The ferredoxin fold is one of the oldest structures capable of catalyzing electron transfer reactions. In nature, only a right-handed topology exists in the ferredoxin fold. To understand how a specific fold-handedness was selected, we analyzed the structural motif using the tools of de novo protein design, searching in an unbiased fashion for backbone geometries that can favorably interact with the tetrahedral iron-sulfur cluster. In silico, we found both left-handed and right-handed folds can be formed, however the right-handed folds provide up to six hydrogen bonds that can stabilize the reduced iron-sulfur cluster, whereas left-handed folds at most form three hydrogen bonds. The difference in electrostatic conformational energy may have influenced selection of topology early in the evolution of iron-sulfur cluster containing proteins. This observation led us to establish a fundamental protein design principle that only right-handed peptide folds can properly interact while maintain redox function. Our results provide guidance in the creation of artificial proteins capable of carrying out redox reactions.
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Affiliation(s)
- J. Dongun Kim
- Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, New Jersey, United States of America
- Environmental Biophysics and Molecular Ecology Program, Institute of Marine and Coastal Sciences, Rutgers University, New Brunswick, New Jersey, United States of America
| | - Agustina Rodriguez-Granillo
- Department of Biochemistry, Robert Wood Johnson Medical School, University of Medicine and Dentistry of New Jersey, Piscataway, New Jersey, United States of America
| | - David A. Case
- Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, New Jersey, United States of America
- BioMaPS Institute for Quantitative Biology, Rutgers University, Piscataway, New Jersey, United States of America
| | - Vikas Nanda
- Department of Biochemistry, Robert Wood Johnson Medical School, University of Medicine and Dentistry of New Jersey, Piscataway, New Jersey, United States of America
| | - Paul G. Falkowski
- Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, New Jersey, United States of America
- Environmental Biophysics and Molecular Ecology Program, Institute of Marine and Coastal Sciences, Rutgers University, New Brunswick, New Jersey, United States of America
- Department of Earth and Planetary Sciences, Rutgers University, New Brunswick, New Jersey, United States of America
- * E-mail:
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43
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Falkowski PG, Algeo T, Codispoti L, Deutsch C, Emerson S, Hales B, Huey RB, Jenkins WJ, Kump LR, Levin LA, Lyons TW, Nelson NB, Schofield OS, Summons R, Talley LD, Thomas E, Whitney F, Pilcher CB. Ocean deoxygenation: Past, present, and future. ACTA ACUST UNITED AC 2011. [DOI: 10.1029/2011eo460001] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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44
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Yan C, Schofield O, Dubinsky Z, Mauzerall D, Falkowski PG, Gorbunov MY. Photosynthetic energy storage efficiency in Chlamydomonas reinhardtii, based on microsecond photoacoustics. Photosynth Res 2011; 108:215-224. [PMID: 21894460 DOI: 10.1007/s11120-011-9682-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2011] [Accepted: 08/15/2011] [Indexed: 05/31/2023]
Abstract
Using a novel, pulsed micro-second time-resolved photoacoustic (PA) instrument, we measured thermal dissipation and energy storage (ES) in the intact cells of wild type (WT) Chlamydomonas reinhardtii, and mutants lacking either PSI or PSII reaction centers (RCs). On this time scale, the kinetic contributions of the thermal expansion component due to heat dissipation of absorbed energy and the negative volume change due to electrostriction induced by charge separation in each of the photosystems could be readily distinguished. Kinetic analysis revealed that PSI and PSII RCs exhibit strikingly different PA signals where PSI is characterized by a strong electrostriction signal and a weak thermal expansion component while PSII has a small electrostriction component and large thermal expansion. The calculated ES efficiencies at ~10 μs were estimated to be 80 ± 5 and 50 ± 13% for PSII-deficient mutants and PSI-deficient mutants, respectively, and 67 ± 2% for WT. The overall ES efficiency was positively correlated with the ratio of PSI to PSI + PSII. Our results suggest that the shallow excitonic trap in PSII limits the efficiency of ES as a result of an evolutionary frozen metabolic framework of two photosystems in all oxygenic photoautotrophs.
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Affiliation(s)
- Chengyi Yan
- Environmental Biophysics and Molecular Ecology Program, Institute of Marine and Coastal Sciences, Rutgers, The State University of New Jersey, New Brunswick, NJ 08901, USA
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45
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Abstract
Mesodinium rubrum (=Myrionecta rubra), a marine ciliate, acquires plastids, mitochondria, and nuclei from cryptophyte algae. Using a strain of M. rubrum isolated from McMurdo Sound, Antarctica, we investigated the photoacclimation potential of this trophically unique organism at a range of low irradiance levels. The compensation growth irradiance for M. rubrum was 0.5 μmol quanta · m(-2) · s(-1) , and growth rate saturated at ∼20 μmol quanta · m(-2) · s(-1) . The strain displayed trends in photosynthetic efficiency and pigment content characteristic of marine phototrophs. Maximum chl a-specific photosynthetic rates were an order of magnitude slower than temperate strains, while growth rates were half as large, suggesting that a thermal limit to enzyme kinetics produces a fundamental limit to cell function. M. rubrum acclimates to light- and temperature-limited polar conditions and closely regulates photosynthesis in its cryptophyte organelles. By acquiring and maintaining physiologically viable, plastic plastids, M. rubrum establishes a selective advantage over purely heterotrophic ciliates but reduces competition with other phototrophs by exploiting a very low-light niche.
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Affiliation(s)
- Holly V Moeller
- Environmental Biophysics and Molecular Ecology Program, Institute of Marine and Coastal Sciences, Rutgers University, 71 Dudley Road, New Brunswick, New Jersey 08901, USA Environmental Biophysics and Molecular Ecology Program, Institute of Marine and Coastal Sciences, Rutgers University, 71 Dudley Road, New Brunswick, New Jersey 08901, USA Department of Earth and Planetary Sciences, Rutgers University, 610 Taylor Road, Piscataway, New Jersey 08854, USA
| | - Matthew D Johnson
- Environmental Biophysics and Molecular Ecology Program, Institute of Marine and Coastal Sciences, Rutgers University, 71 Dudley Road, New Brunswick, New Jersey 08901, USA Environmental Biophysics and Molecular Ecology Program, Institute of Marine and Coastal Sciences, Rutgers University, 71 Dudley Road, New Brunswick, New Jersey 08901, USA Department of Earth and Planetary Sciences, Rutgers University, 610 Taylor Road, Piscataway, New Jersey 08854, USA
| | - Paul G Falkowski
- Environmental Biophysics and Molecular Ecology Program, Institute of Marine and Coastal Sciences, Rutgers University, 71 Dudley Road, New Brunswick, New Jersey 08901, USA Environmental Biophysics and Molecular Ecology Program, Institute of Marine and Coastal Sciences, Rutgers University, 71 Dudley Road, New Brunswick, New Jersey 08901, USA Department of Earth and Planetary Sciences, Rutgers University, 610 Taylor Road, Piscataway, New Jersey 08854, USA
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46
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Whittaker S, Bidle KD, Kustka AB, Falkowski PG. Quantification of nitrogenase in Trichodesmium IMS 101: implications for iron limitation of nitrogen fixation in the ocean. Environ Microbiol Rep 2011; 3:54-8. [PMID: 23761231 DOI: 10.1111/j.1758-2229.2010.00187.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Iron is widely thought to limit nitrogen fixation in the open, oligotrophic ocean due to the low solubility of Fe in oxic seawater and the high Fe demand for the nitrogenase holozyme. However, empirical evidence for Fe limitation of field populations of Trichodesmium based on either incubation experiments or molecular and physiological indicators has not quantitatively related Fe supply to the cellular Fe quotas for nitrogenase. Rather, the Fe required for N2 fixation has been inferred from in vivo catalytic activity. Using a pet14b expression vector, we cloned the nif H gene (encoding the Fe-protein, which contains 4Fe atoms per subunit) from Trichodesmium IMS 101, and purified the His-tagged apoprotein with which we derived a primary standard based on quantitative Western blots. Using a standard curve derived from the cloned Trichodesmium Fe apoprotein, we measured the absolute abundance of the Fe-protein in iron-replete cultures of this marine diazotroph. At peak expression, we calculate 0.04 mg nitrogenase mg(-1) C. Assuming a conservative stoichiometry of two Fe-protein subunits per MoFe protein (which contains 15 Fe atoms per subunit, or a total of 38 atoms of Fe per holozyme), we estimate 236 µmol Fe is bound to nitrogenase per mol cellular C. This estimate is about 10 times greater than the Fe previously calculated to support diazotrophic growth under these conditions. Our results suggest that under bloom conditions in the subtropical North Atlantic and North Pacific, as much as ∼2.22 and 0.06 µmol m(-3) of Fe is bound to Trichodesmium nitrogenase respectively. Such a high quota represents between ∼50% and > 100% summer-time average particulate Fe in surface waters, suggesting the importance of this taxon for the retention and biogeochemical cycling of Fe. Moderate growth (0.10 day(-1) ) towards the end of these blooms would require a vertical flux as high as ∼23 µmol Fe day(-1) m(-2) into the mixed layer.
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Affiliation(s)
- Sherrie Whittaker
- Environmental Biophysics and Molecular Ecology, Institute of Marine and Coastal Sciences, Rutgers, The State University of New Jersey, New Brunswick, NJ, USA. Department of Earth and Environmental Sciences, Rutgers, The State University of New Jersey - Newark, Newark, NJ, USA. Department of Earth and Planetary Sciences, Rutgers, The State University of New Jersey, New Brunswick, NJ, USA
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47
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Affiliation(s)
- Paul G Falkowski
- Environmental Biophysics, Department of Earth and Planetary Sciences and Institute of Marine and Coastal Sciences, Rutgers University, New Brunswick, NJ 08901, USA.
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48
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Abstract
Atmospheric reactions and slow geological processes controlled Earth's earliest nitrogen cycle, and by ~2.7 billion years ago, a linked suite of microbial processes evolved to form the modern nitrogen cycle with robust natural feedbacks and controls. Over the past century, however, the development of new agricultural practices to satisfy a growing global demand for food has drastically disrupted the nitrogen cycle. This has led to extensive eutrophication of fresh waters and coastal zones as well as increased inventories of the potent greenhouse gas nitrous oxide (N(2)O). Microbial processes will ultimately restore balance to the nitrogen cycle, but the damage done by humans to the nitrogen economy of the planet will persist for decades, possibly centuries, if active intervention and careful management strategies are not initiated.
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Affiliation(s)
- Donald E Canfield
- Institute of Biology and Nordic Center for Earth Evolution, University of Southern Denmark, Campusvej 55, Odense M, Denmark.
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49
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Gleick PH, Adams RM, Amasino RM, Anders E, Anderson DJ, Anderson WW, Anselin LE, Arroyo MK, Asfaw B, Ayala FJ, Bax A, Bebbington AJ, Bell G, Bennett MVL, Bennetzen JL, Berenbaum MR, Berlin OB, Bjorkman PJ, Blackburn E, Blamont JE, Botchan MR, Boyer JS, Boyle EA, Branton D, Briggs SP, Briggs WR, Brill WJ, Britten RJ, Broecker WS, Brown JH, Brown PO, Brunger AT, Cairns J, Canfield DE, Carpenter SR, Carrington JC, Cashmore AR, Castilla JC, Cazenave A, Chapin FS, Ciechanover AJ, Clapham DE, Clark WC, Clayton RN, Coe MD, Conwell EM, Cowling EB, Cowling RM, Cox CS, Croteau RB, Crothers DM, Crutzen PJ, Daily GC, Dalrymple GB, Dangl JL, Darst SA, Davies DR, Davis MB, De Camilli PV, Dean C, DeFries RS, Deisenhofer J, Delmer DP, DeLong EF, DeRosier DJ, Diener TO, Dirzo R, Dixon JE, Donoghue MJ, Doolittle RF, Dunne T, Ehrlich PR, Eisenstadt SN, Eisner T, Emanuel KA, Englander SW, Ernst WG, Falkowski PG, Feher G, Ferejohn JA, Fersht A, Fischer EH, Fischer R, Flannery KV, Frank J, Frey PA, Fridovich I, Frieden C, Futuyma DJ, Gardner WR, Garrett CJR, Gilbert W, Goldberg RB, Goodenough WH, Goodman CS, Goodman M, Greengard P, Hake S, Hammel G, Hanson S, Harrison SC, Hart SR, Hartl DL, Haselkorn R, Hawkes K, Hayes JM, Hille B, Hökfelt T, House JS, Hout M, Hunten DM, Izquierdo IA, Jagendorf AT, Janzen DH, Jeanloz R, Jencks CS, Jury WA, Kaback HR, Kailath T, Kay P, Kay SA, Kennedy D, Kerr A, Kessler RC, Khush GS, Kieffer SW, Kirch PV, Kirk K, Kivelson MG, Klinman JP, Klug A, Knopoff L, Kornberg H, Kutzbach JE, Lagarias JC, Lambeck K, Landy A, Langmuir CH, Larkins BA, Le Pichon XT, Lenski RE, Leopold EB, Levin SA, Levitt M, Likens GE, Lippincott-Schwartz J, Lorand L, Lovejoy CO, Lynch M, Mabogunje AL, Malone TF, Manabe S, Marcus J, Massey DS, McWilliams JC, Medina E, Melosh HJ, Meltzer DJ, Michener CD, Miles EL, Mooney HA, Moore PB, Morel FMM, Mosley-Thompson ES, Moss B, Munk WH, Myers N, Nair GB, Nathans J, Nester EW, Nicoll RA, Novick RP, O'Connell JF, Olsen PE, Opdyke ND, Oster GF, Ostrom E, Pace NR, Paine RT, Palmiter RD, Pedlosky J, Petsko GA, Pettengill GH, Philander SG, Piperno DR, Pollard TD, Price PB, Reichard PA, Reskin BF, Ricklefs RE, Rivest RL, Roberts JD, Romney AK, Rossmann MG, Russell DW, Rutter WJ, Sabloff JA, Sagdeev RZ, Sahlins MD, Salmond A, Sanes JR, Schekman R, Schellnhuber J, Schindler DW, Schmitt J, Schneider SH, Schramm VL, Sederoff RR, Shatz CJ, Sherman F, Sidman RL, Sieh K, Simons EL, Singer BH, Singer MF, Skyrms B, Sleep NH, Smith BD, Snyder SH, Sokal RR, Spencer CS, Steitz TA, Strier KB, Südhof TC, Taylor SS, Terborgh J, Thomas DH, Thompson LG, Tjian RT, Turner MG, Uyeda S, Valentine JW, Valentine JS, Van Etten JL, van Holde KE, Vaughan M, Verba S, von Hippel PH, Wake DB, Walker A, Walker JE, Watson EB, Watson PJ, Weigel D, Wessler SR, West-Eberhard MJ, White TD, Wilson WJ, Wolfenden RV, Wood JA, Woodwell GM, Wright HE, Wu C, Wunsch C, Zoback ML. Climate change and the integrity of science. Science 2010; 328:689-90. [PMID: 20448167 DOI: 10.1126/science.328.5979.689] [Citation(s) in RCA: 102] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
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Vittadello M, Gorbunov MY, Mastrogiovanni DT, Wielunski LS, Garfunkel EL, Guerrero F, Kirilovsky D, Sugiura M, Rutherford AW, Safari A, Falkowski PG. Photoelectron generation by photosystem II core complexes tethered to gold surfaces. ChemSusChem 2010; 3:471-475. [PMID: 20209512 DOI: 10.1002/cssc.200900255] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
By using a nondestructive, ultrasensitive, fluorescence kinetic technique, we measure in situ the photochemical energy conversion efficiency and electron transfer kinetics on the acceptor side of histidine-tagged photosystem II core complexes tethered to gold surfaces. Atomic force microscopy images coupled with Rutherford backscattering spectroscopy measurements further allow us to assess the quality, number of layers, and surface density of the reaction center films. Based on these measurements, we calculate that the theoretical photoelectronic current density available for an ideal monolayer of core complexes is 43 microA cm(-2) at a photon flux density of 2000 micromol quanta m(-2) s(-1) between 365 and 750 nm. While this current density is approximately two orders of magnitude lower than the best organic photovoltaic cells (for an equivalent area), it provides an indication for future improvement strategies. The efficiency could be improved by increasing the optical cross section, by tuning the electron transfer physics between the core complexes and the metal surface, and by developing a multilayer structure, thereby making biomimetic photoelectron devices for hydrogen generation and chemical sensing more viable.
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Affiliation(s)
- Michele Vittadello
- Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA.
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