1
|
Every refuge has its price: Ostreobium as a model for understanding how algae can live in rock and stay in business. Semin Cell Dev Biol 2023; 134:27-36. [PMID: 35341677 DOI: 10.1016/j.semcdb.2022.03.010] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Revised: 02/20/2022] [Accepted: 03/08/2022] [Indexed: 11/23/2022]
Abstract
Ostreobium is a siphonous green alga in the Bryopsidales (Chlorophyta) that burrows into calcium carbonate (CaCO3) substrates. In this habitat, it lives under environmental conditions unusual for an alga (i.e., low light and low oxygen) and it is a major agent of carbonate reef bioerosion. In coral skeletons, Ostreobium can form conspicuous green bands recognizable by the naked eye and it is thought to contribute to the coral's nutritional needs. With coral reefs in global decline, there is a renewed focus on understanding Ostreobium biology and its roles in the coral holobiont. This review summarizes knowledge on Ostreobium's morphological structure, biodiversity and evolution, photosynthesis, mechanism of bioerosion and its role as a member of the coral holobiont. We discuss the resources available to study Ostreobium biology, lay out some of the uncharted territories in Ostreobium biology and offer perspectives for future research.
Collapse
|
2
|
Evolution of Phytoplankton in Relation to Their Physiological Traits. JOURNAL OF MARINE SCIENCE AND ENGINEERING 2022. [DOI: 10.3390/jmse10020194] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Defining the physiological traits that characterise phytoplankton involves comparison with related organisms in benthic habitats. Comparison of survival time in darkness under natural conditions requires more information. Gas vesicles and flagella as mechanisms of upward movement relative to surrounding water, allowing periodic vertical migration, are not confined to plankton, although buoyancy changes related to compositional changes of a large central vacuole may be restricted to plankton. Benthic microalgae have the same range of photosynthetic pigments as phytoplankton; it is not clear if there are differences in the rate of regulation and acclimation of photosynthetic machinery to variations in irradiance for phytoplankton and for microphytobenthos. There are inadequate data to determine if responses to variations in frequency or magnitude of changes in the supply of inorganic carbon, nitrogen or phosphorus differ between phytoplankton and benthic microalgae. Phagophotomixotrophy and osmophotomixotrophy occur in both phytoplankton and benthic microalgae. Further progress in identifying physiological traits specific to phytoplankton requires more experimentation on benthic microalgae that are closely related to planktonic microalgae, with attention to whether the benthic algae examined have, as far as can be determined, never been planktonic during their evolution or are derived from planktonic ancestors.
Collapse
|
3
|
Sheng X, Liu Z, Kim E, Minagawa J. Plant and Algal PSII-LHCII Supercomplexes: Structure, Evolution and Energy Transfer. PLANT & CELL PHYSIOLOGY 2021; 62:1108-1120. [PMID: 34038564 DOI: 10.1093/pcp/pcab072] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Revised: 04/19/2021] [Accepted: 05/25/2021] [Indexed: 06/12/2023]
Abstract
Photosynthesis is the process conducted by plants and algae to capture photons and store their energy in chemical forms. The light-harvesting, excitation transfer, charge separation and electron transfer in photosystem II (PSII) are the critical initial reactions of photosynthesis and thereby largely determine its overall efficiency. In this review, we outline the rapidly accumulating knowledge about the architectures and assemblies of plant and green algal PSII-light harvesting complex II (LHCII) supercomplexes, with a particular focus on new insights provided by the recent high-resolution cryo-electron microscopy map of the supercomplexes from a green alga Chlamydomonas reinhardtii. We make pair-wise comparative analyses between the supercomplexes from plants and green algae to gain insights about the evolution of the PSII-LHCII supercomplexes involving the peripheral small PSII subunits that might have been acquired during the evolution and about the energy transfer pathways that define their light-harvesting and photoprotective properties.
Collapse
Affiliation(s)
- Xin Sheng
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Chaoyang District, Beijing, 100101, China
- College of Life Sciences, University of Chinese Academy of Sciences, 19(A) Yuquan Road, Shijingshan District, Beijing, 100049, China
| | - Zhenfeng Liu
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Chaoyang District, Beijing, 100101, China
- College of Life Sciences, University of Chinese Academy of Sciences, 19(A) Yuquan Road, Shijingshan District, Beijing, 100049, China
| | - Eunchul Kim
- Division of Environmental Photobiology, National Institute for Basic Biology, 38 Nishigonaka, Myodaiji, Okazaki, Aichi 444-8585, Japan
- Department of Basic Biology, School of Life Science, The Graduate University for Advanced Studies, SOKENDAI, 38 Nishigonaka, Myodaiji, Okazaki, Aichi 444-8585, Japan
| | - Jun Minagawa
- Division of Environmental Photobiology, National Institute for Basic Biology, 38 Nishigonaka, Myodaiji, Okazaki, Aichi 444-8585, Japan
- Department of Basic Biology, School of Life Science, The Graduate University for Advanced Studies, SOKENDAI, 38 Nishigonaka, Myodaiji, Okazaki, Aichi 444-8585, Japan
| |
Collapse
|
4
|
Aso M, Matsumae R, Tanaka A, Tanaka R, Takabayashi A. Unique Peripheral Antennas in the Photosystems of the Streptophyte Alga Mesostigma viride. PLANT & CELL PHYSIOLOGY 2021; 62:436-446. [PMID: 33416834 DOI: 10.1093/pcp/pcaa172] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2020] [Accepted: 12/19/2020] [Indexed: 06/12/2023]
Abstract
Land plants evolved from a single group of streptophyte algae. One of the key factors needed for adaptation to a land environment is the modification in the peripheral antenna systems of photosystems (PSs). Here, the PSs of Mesostigma viride, one of the earliest-branching streptophyte algae, were analyzed to gain insight into their evolution. Isoform sequencing and phylogenetic analyses of light-harvesting complexes (LHCs) revealed that M. viride possesses three algae-specific LHCs, including algae-type LHCA2, LHCA9 and LHCP, while the streptophyte-specific LHCB6 was not identified. These data suggest that the acquisition of LHCB6 and the loss of algae-type LHCs occurred after the M. viride lineage branched off from other streptophytes. Clear-native (CN)-polyacrylamide gel electrophoresis (PAGE) resolved the photosynthetic complexes, including the PSI-PSII megacomplex, PSII-LHCII, two PSI-LHCI-LHCIIs, PSI-LHCI and the LHCII trimer. Results indicated that the higher-molecular weight PSI-LHCI-LHCII likely had more LHCII than the lower-molecular weight one, a unique feature of M. viride PSs. CN-PAGE coupled with mass spectrometry strongly suggested that the LHCP was bound to PSII-LHCII, while the algae-type LHCA2 and LHCA9 were bound to PSI-LHCI, both of which are different from those in land plants. Results of the present study strongly suggest that M. viride PSs possess unique features that were inherited from a common ancestor of streptophyte and chlorophyte algae.
Collapse
Affiliation(s)
- Michiki Aso
- Institute of Low Temperature Science, Hokkaido University, N19 W8 Kita-ku, Sapporo, 060-0819 Japan
| | - Renon Matsumae
- Institute of Low Temperature Science, Hokkaido University, N19 W8 Kita-ku, Sapporo, 060-0819 Japan
| | - Ayumi Tanaka
- Institute of Low Temperature Science, Hokkaido University, N19 W8 Kita-ku, Sapporo, 060-0819 Japan
| | - Ryouichi Tanaka
- Institute of Low Temperature Science, Hokkaido University, N19 W8 Kita-ku, Sapporo, 060-0819 Japan
| | - Atsushi Takabayashi
- Institute of Low Temperature Science, Hokkaido University, N19 W8 Kita-ku, Sapporo, 060-0819 Japan
| |
Collapse
|
5
|
Bag P. Light Harvesting in Fluctuating Environments: Evolution and Function of Antenna Proteins across Photosynthetic Lineage. PLANTS (BASEL, SWITZERLAND) 2021; 10:1184. [PMID: 34200788 PMCID: PMC8230411 DOI: 10.3390/plants10061184] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Revised: 05/31/2021] [Accepted: 06/02/2021] [Indexed: 02/07/2023]
Abstract
Photosynthesis is the major natural process that can harvest and harness solar energy into chemical energy. Photosynthesis is performed by a vast number of organisms from single cellular bacteria to higher plants and to make the process efficient, all photosynthetic organisms possess a special type of pigment protein complex(es) that is (are) capable of trapping light energy, known as photosynthetic light-harvesting antennae. From an evolutionary point of view, simpler (unicellular) organisms typically have a simple antenna, whereas higher plants possess complex antenna systems. The higher complexity of the antenna systems provides efficient fine tuning of photosynthesis. This relationship between the complexity of the antenna and the increasing complexity of the organism is mainly related to the remarkable acclimation capability of complex organisms under fluctuating environmental conditions. These antenna complexes not only harvest light, but also provide photoprotection under fluctuating light conditions. In this review, the evolution, structure, and function of different antenna complexes, from single cellular organisms to higher plants, are discussed in the context of the ability to acclimate and adapt to cope under fluctuating environmental conditions.
Collapse
Affiliation(s)
- Pushan Bag
- Department of Plant Physiology, Umeå Plant Science Centre, UPSC, Umeå University, 90736 Umeå, Sweden
| |
Collapse
|
6
|
Iha C, Dougan KE, Varela JA, Avila V, Jackson CJ, Bogaert KA, Chen Y, Judd LM, Wick R, Holt KE, Pasella MM, Ricci F, Repetti SI, Medina M, Marcelino VR, Chan CX, Verbruggen H. Genomic adaptations to an endolithic lifestyle in the coral-associated alga Ostreobium. Curr Biol 2021; 31:1393-1402.e5. [PMID: 33548192 DOI: 10.1016/j.cub.2021.01.018] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Revised: 11/21/2020] [Accepted: 01/07/2021] [Indexed: 02/06/2023]
Abstract
The green alga Ostreobium is an important coral holobiont member, playing key roles in skeletal decalcification and providing photosynthate to bleached corals that have lost their dinoflagellate endosymbionts. Ostreobium lives in the coral's skeleton, a low-light environment with variable pH and O2 availability. We present the Ostreobium nuclear genome and a metatranscriptomic analysis of healthy and bleached corals to improve our understanding of Ostreobium's adaptations to its extreme environment and its roles as a coral holobiont member. The Ostreobium genome has 10,663 predicted protein-coding genes and shows adaptations for life in low and variable light conditions and other stressors in the endolithic environment. This alga presents a rich repertoire of light-harvesting complex proteins but lacks many genes for photoprotection and photoreceptors. It also has a large arsenal of genes for oxidative stress response. An expansion of extracellular peptidases suggests that Ostreobium may supplement its energy needs by feeding on the organic skeletal matrix, and a diverse set of fermentation pathways allows it to live in the anoxic skeleton at night. Ostreobium depends on other holobiont members for vitamin B12, and our metatranscriptomes identify potential bacterial sources. Metatranscriptomes showed Ostreobium becoming a dominant agent of photosynthesis in bleached corals and provided evidence for variable responses among coral samples and different Ostreobium genotypes. Our work provides a comprehensive understanding of the adaptations of Ostreobium to its extreme environment and an important genomic resource to improve our comprehension of coral holobiont resilience, bleaching, and recovery.
Collapse
Affiliation(s)
- Cintia Iha
- School of BioSciences, University of Melbourne, Melbourne, VIC 3010, Australia.
| | - Katherine E Dougan
- School of Chemistry and Molecular Biosciences and Australian Centre for Ecogenomics, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Javier A Varela
- School of Microbiology, Centre for Synthetic Biology and Biotechnology, Environmental Research Institute, and APC Microbiome Institute, University College Cork, Cork T12 YN60, Ireland
| | - Viridiana Avila
- Pennsylvania State University, University Park, PA 16802, USA
| | | | - Kenny A Bogaert
- Phycology Research Group, Ghent University, Krijgslaan 281 S8, 9000 Gent, Belgium
| | - Yibi Chen
- School of Chemistry and Molecular Biosciences and Australian Centre for Ecogenomics, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Louise M Judd
- Department of Infectious Diseases, Central Clinical School, Monash University, Melbourne, VIC 3004, Australia
| | - Ryan Wick
- Department of Infectious Diseases, Central Clinical School, Monash University, Melbourne, VIC 3004, Australia
| | - Kathryn E Holt
- Department of Infectious Diseases, Central Clinical School, Monash University, Melbourne, VIC 3004, Australia; London School of Hygiene & Tropical Medicine, London WC1E 7HT, UK
| | - Marisa M Pasella
- School of BioSciences, University of Melbourne, Melbourne, VIC 3010, Australia
| | - Francesco Ricci
- School of BioSciences, University of Melbourne, Melbourne, VIC 3010, Australia
| | - Sonja I Repetti
- School of BioSciences, University of Melbourne, Melbourne, VIC 3010, Australia
| | - Mónica Medina
- Pennsylvania State University, University Park, PA 16802, USA
| | - Vanessa R Marcelino
- Centre for Innate Immunity and Infectious Diseases, Hudson Institute of Medical Research, Clayton, VIC 3168, Australia
| | - Cheong Xin Chan
- School of Chemistry and Molecular Biosciences and Australian Centre for Ecogenomics, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Heroen Verbruggen
- School of BioSciences, University of Melbourne, Melbourne, VIC 3010, Australia.
| |
Collapse
|
7
|
Dall'Osto L, Cazzaniga S, Zappone D, Bassi R. Monomeric light harvesting complexes enhance excitation energy transfer from LHCII to PSII and control their lateral spacing in thylakoids. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2020; 1861:148035. [DOI: 10.1016/j.bbabio.2019.06.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2019] [Revised: 06/13/2019] [Accepted: 06/15/2019] [Indexed: 10/26/2022]
|
8
|
Le Goff M, Delbrut A, Quinton M, Pradelles R, Bescher M, Burel A, Schoefs B, Sergent O, Lagadic-Gossmann D, Le Ferrec E, Ulmann L. Protective Action of Ostreococcus tauri and Phaeodactylum tricornutum Extracts towards Benzo[a]Pyrene-Induced Cytotoxicity in Endothelial Cells. Mar Drugs 2019; 18:E3. [PMID: 31861403 PMCID: PMC7024323 DOI: 10.3390/md18010003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2019] [Revised: 12/13/2019] [Accepted: 12/14/2019] [Indexed: 12/31/2022] Open
Abstract
Marine microalgae are known to be a source of bioactive molecules of interest to human health, such as n-3 polyunsaturated fatty acids (n-3 PUFAs) and carotenoids. The fact that some of these natural compounds are known to exhibit anti-inflammatory, antioxidant, anti-proliferative, and apoptosis-inducing effects, demonstrates their potential use in preventing cancers and cardiovascular diseases (CVDs). Benzo[a]pyrene (B[a]P), a polycyclic aromatic hydrocarbon (PAH), is an ubiquitous environmental pollutant known to contribute to the development or aggravation of human diseases, such as cancer, CVDs, and immune dysfunction. Most of these deleterious effects are related to the activation of the polycyclic aromatic hydrocarbon receptor (AhR). In this context, two ethanolic microalgal extracts with concentrations of 0.1 to 5 µg/mL are tested, Ostreoccoccus tauri (OT) and Phaeodactylum tricornutum (PT), in order to evaluate and compare their potential effects towards B[a]P-induced toxicity in endothelial HMEC-1 cells. Our results indicate that the OT extract can influence the toxicity of B[a]P. Indeed, apoptosis and the production of extracellular vesicles were decreased, likely through the reduction of the expression of CYP1A1, a B[a]P bioactivation enzyme. Furthermore, the B[a]P-induced expression of the inflammatory cytokines IL-8 and IL1-β was reduced. The PT extract only inhibited the expression of the B[a]P-induced cytokine IL-8 expression. The OT extract therefore seems to be a good candidate for counteracting the B[a]P toxicity.
Collapse
Affiliation(s)
- Manon Le Goff
- EA 2160 Mer Molécules Santé—MIMMA, IUML FR-3473 CNRS, Le Mans Université, F-53020 Laval, France; (M.L.G.)
- Univ Rennes, Inserm, EHESP, Irset (Institut de recherche en santé, environnement et travail)—UMR_S 1085, F-35000 Rennes, France; (M.B.); (O.S.); (D.L.-G.)
| | - Antoine Delbrut
- Microphyt, 713 Route de Mudaison, 34630 Baillargues, France; (A.D.); (M.Q.); (R.P.)
| | - Marie Quinton
- Microphyt, 713 Route de Mudaison, 34630 Baillargues, France; (A.D.); (M.Q.); (R.P.)
| | - Rémi Pradelles
- Microphyt, 713 Route de Mudaison, 34630 Baillargues, France; (A.D.); (M.Q.); (R.P.)
| | - Maelle Bescher
- Univ Rennes, Inserm, EHESP, Irset (Institut de recherche en santé, environnement et travail)—UMR_S 1085, F-35000 Rennes, France; (M.B.); (O.S.); (D.L.-G.)
| | - Agnès Burel
- Univ Rennes, Biosit–UMS 3480, US_S 018, F-35000 Rennes, France; (A.B.)
| | - Benoît Schoefs
- EA 2160 Mer Molécules Santé—MIMMA, IUML FR-3473 CNRS, Le Mans Université, F-72000 Le Mans, France; (B.S.)
| | - Odile Sergent
- Univ Rennes, Inserm, EHESP, Irset (Institut de recherche en santé, environnement et travail)—UMR_S 1085, F-35000 Rennes, France; (M.B.); (O.S.); (D.L.-G.)
| | - Dominique Lagadic-Gossmann
- Univ Rennes, Inserm, EHESP, Irset (Institut de recherche en santé, environnement et travail)—UMR_S 1085, F-35000 Rennes, France; (M.B.); (O.S.); (D.L.-G.)
| | - Eric Le Ferrec
- Univ Rennes, Inserm, EHESP, Irset (Institut de recherche en santé, environnement et travail)—UMR_S 1085, F-35000 Rennes, France; (M.B.); (O.S.); (D.L.-G.)
| | - Lionel Ulmann
- EA 2160 Mer Molécules Santé—MIMMA, IUML FR-3473 CNRS, Le Mans Université, F-53020 Laval, France; (M.L.G.)
| |
Collapse
|
9
|
A streamlined and predominantly diploid genome in the tiny marine green alga Chloropicon primus. Nat Commun 2019; 10:4061. [PMID: 31492891 PMCID: PMC6731263 DOI: 10.1038/s41467-019-12014-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2018] [Accepted: 08/16/2019] [Indexed: 12/11/2022] Open
Abstract
Tiny marine green algae issued from two deep branches of the Chlorophyta, the Mamiellophyceae and Chloropicophyceae, dominate different regions of the oceans and play key roles in planktonic communities. Considering that the Mamiellophyceae is the sole lineage of prasinophyte algae that has been intensively investigated, the extent to which these two algal groups differ in their metabolic capacities and cellular processes is currently unknown. To address this gap of knowledge, we investigate here the nuclear genome sequence of a member of the Chloropicophyceae, Chloropicon primus. Among the main biological insights that emerge from this 17.4 Mb genome, we find an unexpected diploid structure for most chromosomes and a propionate detoxification pathway in green algae. Our results support the notion that separate events of genome minimization, which entailed differential losses of genes/pathways, have occurred in the Chloropicophyceae and Mamiellophyceae, suggesting different strategies of adaptation to oceanic environments.
Collapse
|
10
|
Büchel C. Light harvesting complexes in chlorophyll c-containing algae. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2019; 1861:148027. [PMID: 31153887 DOI: 10.1016/j.bbabio.2019.05.003] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Revised: 05/22/2019] [Accepted: 05/24/2019] [Indexed: 12/30/2022]
Abstract
Besides the so-called 'green lineage' of eukaryotic photosynthetic organisms that include vascular plants, a huge variety of different algal groups exist that also harvest light by means of membrane intrinsic light harvesting proteins (Lhc). The main taxa of these algae are the Cryptophytes, Haptophytes, Dinophytes, Chromeridae and the Heterokonts, the latter including diatoms, brown algae, Xanthophyceae and Eustigmatophyceae amongst others. Despite the similarity in Lhc proteins between vascular plants and these algae, pigmentation is significantly different since no Chl b is bound, but often replaced by Chl c, and a large diversity in carotenoids functioning in light harvesting and/or photoprotection is present. Due to the presence of Chl c in most of the taxa the name 'Chl c-containing organisms' has become common, however, Chl b-less is more precise since some harbour Lhc proteins that only bind one type of Chl, Chl a. In recent years huge progress has been made about the occurrence and function of Lhc in diatoms, so-called fucoxanthin chlorophyll proteins (FCP), where also the first molecular structure became available recently. In addition, especially energy transfer amongst the unusual pigments bound was intensively studied in many of these groups. This review summarises the present knowledge about the molecular structure, the arrangement of the different Lhc in complexes, the excitation energy transfer abilities and the involvement in photoprotection of the different Lhc systems in the so-called Chl c-containing organisms. This article is part of a Special Issue entitled Light harvesting, edited by Dr. Roberta Croce.
Collapse
Affiliation(s)
- Claudia Büchel
- Institute of Molecular Biosciences, Goethe University Frankfurt, Max-von-Laue Straße 9, 60438 Frankfurt, Germany.
| |
Collapse
|
11
|
Guyon JB, Vergé V, Schatt P, Lozano JC, Liennard M, Bouget FY. Comparative Analysis of Culture Conditions for the Optimization of Carotenoid Production in Several Strains of the Picoeukaryote Ostreococcus. Mar Drugs 2018; 16:md16030076. [PMID: 29495580 PMCID: PMC5867620 DOI: 10.3390/md16030076] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2018] [Revised: 02/16/2018] [Accepted: 02/16/2018] [Indexed: 01/09/2023] Open
Abstract
Microalgae are promising sources for the sustainable production of compounds of interest for biotechnologies. Compared to higher plants, microalgae have a faster growth rate and can be grown in industrial photobioreactors. The microalgae biomass contains specific metabolites of high added value for biotechnology such as lipids, polysaccharides or carotenoid pigments. Studying carotenogenesis is important for deciphering the mechanisms of adaptation to stress tolerance as well as for biotechnological production. In recent years, the picoeukaryote Ostreococcustauri has emerged as a model organism thanks to the development of powerful genetic tools. Several strains of Ostreococcus isolated from different environments have been characterized with respect to light response or iron requirement. We have compared the carotenoid contents and growth rates of strains of Ostreococcus (OTTH595, RCC802 and RCC809) under a wide range of light, salinity and temperature conditions. Carotenoid profiles and productivities varied in a strain-specific and stress-dependent manner. Our results also illustrate that phylogenetically related microalgal strains originating from different ecological niches present specific interests for the production of specific molecules under controlled culture conditions.
Collapse
Affiliation(s)
- Jean-Baptiste Guyon
- Observatoire Océanologique, UMR 7621 Laboratoire d'Océanographie Microbienne, Université de Pierre et Marie Curie (Paris 06), Sorbonne Universités, 66650 Banyuls-sur-Mer, France.
| | - Valérie Vergé
- Observatoire Océanologique, UMR 7621 Laboratoire d'Océanographie Microbienne, Université de Pierre et Marie Curie (Paris 06), Sorbonne Universités, 66650 Banyuls-sur-Mer, France.
| | - Philippe Schatt
- Observatoire Océanologique, UMR 7621 Laboratoire d'Océanographie Microbienne, Université de Pierre et Marie Curie (Paris 06), Sorbonne Universités, 66650 Banyuls-sur-Mer, France.
| | - Jean-Claude Lozano
- Observatoire Océanologique, UMR 7621 Laboratoire d'Océanographie Microbienne, Université de Pierre et Marie Curie (Paris 06), Sorbonne Universités, 66650 Banyuls-sur-Mer, France.
| | - Marion Liennard
- Observatoire Océanologique, UMR 7621 Laboratoire d'Océanographie Microbienne, Université de Pierre et Marie Curie (Paris 06), Sorbonne Universités, 66650 Banyuls-sur-Mer, France.
| | - François-Yves Bouget
- Observatoire Océanologique, UMR 7621 Laboratoire d'Océanographie Microbienne, Université de Pierre et Marie Curie (Paris 06), Sorbonne Universités, 66650 Banyuls-sur-Mer, France.
| |
Collapse
|
12
|
Schaller-Laudel S, Latowski D, Jemioła-Rzemińska M, Strzałka K, Daum S, Bacia K, Wilhelm C, Goss R. Influence of thylakoid membrane lipids on the structure of aggregated light-harvesting complexes of the diatom Thalassiosira pseudonana and the green alga Mantoniella squamata. PHYSIOLOGIA PLANTARUM 2017; 160:339-358. [PMID: 28317130 DOI: 10.1111/ppl.12565] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2016] [Revised: 02/02/2017] [Accepted: 02/17/2017] [Indexed: 05/25/2023]
Abstract
The study investigated the effect of the thylakoid membrane lipids monogalactosyldiacylglycerol (MGDG), digalactosyldiacylglycerol (DGDG), sulphoquinovosyldiacylglycerol (SQDG) and phosphatidylglycerol (PG) on the structure of two algal light-harvesting complexes (LHCs). In contrast to higher plants whose thylakoid membranes are characterized by an enrichment of the neutral galactolipids MGDG and DGDG, both the green alga Mantoniella squamata and the centric diatom Thalassiosira pseudonana contain membranes with a high content of the negatively charged lipids SQDG and PG. The algal thylakoids do not show the typical grana-stroma differentiation of higher plants but a regular arrangement. To analyze the effect of the membrane lipids, the fucoxanthin chlorophyll protein (FCP) complex of T. pseudonana and the LHC of M. squamata (MLHC) were prepared by successive cation precipitation using Triton X-100 as detergent. With this method, it is possible to isolate LHCs with a reduced amount of associated lipids in an aggregated state. The results from 77 K fluorescence and photon correlation spectroscopy show that neither the neutral galactolipids nor the negatively charged lipids are able to significantly alter the aggregation state of the FCP or the MLHC. This is in contrast to higher plants where SQDG and PG lead to a strong disaggregation of the LHCII whereas MGDG and DGDG induce the formation of large macroaggregates. The results indicate that LHCs which are integrated into thylakoid membranes with a high amount of negatively charged lipids and a regular arrangement are less sensitive to lipid-induced structural alterations than their counterparts in membranes enriched in neutral lipids with a grana-stroma differentiation.
Collapse
Affiliation(s)
| | - Dariusz Latowski
- Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Krakow, 30-387, Poland
| | | | - Kazimierz Strzałka
- Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Krakow, 30-387, Poland
- Malopolska Centre of Biotechnology, Jagiellonian University, Krakow, 30-387, Poland
| | - Sebastian Daum
- Institute of Chemistry, Martin-Luther-University Halle-Wittenberg, Halle, D-06120, Germany
| | - Kirsten Bacia
- Institute of Chemistry, Martin-Luther-University Halle-Wittenberg, Halle, D-06120, Germany
| | - Christian Wilhelm
- Institute of Biology, University of Leipzig, Leipzig, D-04103, Germany
| | - Reimund Goss
- Institute of Biology, University of Leipzig, Leipzig, D-04103, Germany
| |
Collapse
|
13
|
Responses of the picoprasinophyte Micromonas commoda to light and ultraviolet stress. PLoS One 2017; 12:e0172135. [PMID: 28278262 PMCID: PMC5344333 DOI: 10.1371/journal.pone.0172135] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2016] [Accepted: 01/31/2017] [Indexed: 11/19/2022] Open
Abstract
Micromonas is a unicellular marine green alga that thrives from tropical to polar ecosystems. We investigated the growth and cellular characteristics of acclimated mid-exponential phase Micromonas commoda RCC299 over multiple light levels and over the diel cycle (14:10 hour light:dark). We also exposed the light:dark acclimated M. commoda to experimental shifts from moderate to high light (HL), and to HL plus ultraviolet radiation (HL+UV), 4.5 hours into the light period. Cellular responses of this prasinophyte were quantified by flow cytometry and changes in gene expression by qPCR and RNA-seq. While proxies for chlorophyll a content and cell size exhibited similar diel variations in HL and controls, with progressive increases during day and decreases at night, both parameters sharply decreased after the HL+UV shift. Two distinct transcriptional responses were observed among chloroplast genes in the light shift experiments: i) expression of transcription and translation-related genes decreased over the time course, and this transition occurred earlier in treatments than controls; ii) expression of several photosystem I and II genes increased in HL relative to controls, as did the growth rate within the same diel period. However, expression of these genes decreased in HL+UV, likely as a photoprotective mechanism. RNA-seq also revealed two genes in the chloroplast genome, ycf2-like and ycf1-like, that had not previously been reported. The latter encodes the second largest chloroplast protein in Micromonas and has weak homology to plant Ycf1, an essential component of the plant protein translocon. Analysis of several nuclear genes showed that the expression of LHCSR2, which is involved in non-photochemical quenching, and five light-harvesting-like genes, increased 30 to >50-fold in HL+UV, but was largely unchanged in HL and controls. Under HL alone, a gene encoding a novel nitrite reductase fusion protein (NIRFU) increased, possibly reflecting enhanced N-assimilation under the 625 μmol photons m-2 s-1 supplied in the HL treatment. NIRFU’s domain structure suggests it may have more efficient electron transfer than plant NIR proteins. Our analyses indicate that Micromonas can readily respond to abrupt environmental changes, such that strong photoinhibition was provoked by combined exposure to HL and UV, but a ca. 6-fold increase in light was stimulatory.
Collapse
|
14
|
Lopes Dos Santos A, Gourvil P, Tragin M, Noël MH, Decelle J, Romac S, Vaulot D. Diversity and oceanic distribution of prasinophytes clade VII, the dominant group of green algae in oceanic waters. ISME JOURNAL 2016; 11:512-528. [PMID: 27779617 DOI: 10.1038/ismej.2016.120] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2016] [Revised: 07/28/2016] [Accepted: 08/05/2016] [Indexed: 12/30/2022]
Abstract
Prasinophytes clade VII is a group of pico/nano-planktonic green algae (division Chlorophyta) for which numerous ribosomal RNA (rRNA) sequences have been retrieved from the marine environment in the last 15 years. A large number of strains have also been isolated but have not yet received a formal taxonomic description. A phylogenetic analysis of available strains using both the nuclear 18S and plastidial 16S rRNA genes demonstrates that this group composes at least 10 different clades: A1-A7 and B1-B3. Analysis of sequences from the variable V9 region of the 18S rRNA gene collected during the Tara Oceans expedition and in the frame of the Ocean Sampling Day consortium reveal that clade VII is the dominant Chlorophyta group in oceanic waters, replacing Mamiellophyceae, which have this role in coastal waters. At some location, prasinophytes clade VII can even be the dominant photosynthetic eukaryote representing up to 80% of photosynthetic metabarcodes overall. B1 and A4 are the overall dominant clades and different clades seem to occupy distinct niches, for example, A6 is dominant in surface Mediterranean Sea waters, whereas A4 extend to high temperate latitudes. Our work demonstrates that prasinophytes clade VII constitute a highly diversified group, which is a key component of phytoplankton in open oceanic waters but has been neglected in the conceptualization of marine microbial diversity and carbon cycle.
Collapse
Affiliation(s)
- Adriana Lopes Dos Santos
- Sorbonne Universités, UPMC Université Paris 06, CNRS, UMR 7144 Station Biologique de Roscoff, Roscoff, France
| | - Priscillia Gourvil
- Sorbonne Universités, UPMC Université Paris 06, CNRS, UMR 7144 Station Biologique de Roscoff, Roscoff, France
| | - Margot Tragin
- Sorbonne Universités, UPMC Université Paris 06, CNRS, UMR 7144 Station Biologique de Roscoff, Roscoff, France
| | | | - Johan Decelle
- Sorbonne Universités, UPMC Université Paris 06, CNRS, UMR 7144 Station Biologique de Roscoff, Roscoff, France.,Department of Isotope Biogeochemistry, Helmholtz Centre for Environmental Research - UFZ, Leipzig, Germany
| | - Sarah Romac
- Sorbonne Universités, UPMC Université Paris 06, CNRS, UMR 7144 Station Biologique de Roscoff, Roscoff, France
| | - Daniel Vaulot
- Sorbonne Universités, UPMC Université Paris 06, CNRS, UMR 7144 Station Biologique de Roscoff, Roscoff, France
| |
Collapse
|
15
|
Blatt A, Bauch ME, Pörschke Y, Lohr M. A lycopene β-cyclase/lycopene ε-cyclase/light-harvesting complex-fusion protein from the green alga Ostreococcus lucimarinus can be modified to produce α-carotene and β-carotene at different ratios. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2015; 82:582-95. [PMID: 25759133 DOI: 10.1111/tpj.12826] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2014] [Revised: 02/27/2015] [Accepted: 03/06/2015] [Indexed: 05/08/2023]
Abstract
Biosynthesis of asymmetric carotenoids such as α-carotene and lutein in plants and green algae involves the two enzymes lycopene β-cyclase (LCYB) and lycopene ε-cyclase (LCYE). The two cyclases are closely related and probably resulted from an ancient gene duplication. While in most plants investigated so far the two cyclases are encoded by separate genes, prasinophyte algae of the order Mamiellales contain a single gene encoding a fusion protein comprised of LCYB, LCYE and a C-terminal light-harvesting complex (LHC) domain. Here we show that the lycopene cyclase fusion protein from Ostreococcus lucimarinus catalyzed the simultaneous formation of α-carotene and β-carotene when heterologously expressed in Escherichia coli. The stoichiometry of the two products in E. coli could be altered by gradual truncation of the C-terminus, suggesting that the LHC domain may be involved in modulating the relative activities of the two cyclase domains in the algae. Partial deletions of the linker region between the cyclase domains or replacement of one or both cyclase domains with the corresponding cyclases from the green alga Chlamydomonas reinhardtii resulted in pronounced shifts of the α-carotene-to-β-carotene ratio, indicating that both the relative activities of the cyclase domains and the overall structure of the fusion protein have a strong impact on the product stoichiometry. The possibility to tune the product ratio of the lycopene cyclase fusion protein from Mamiellales renders it useful for the biotechnological production of the asymmetric carotenoids α-carotene or lutein in bacteria or fungi.
Collapse
Affiliation(s)
- Andreas Blatt
- Institut für Allgemeine Botanik, Johannes Gutenberg-Universität, 55099, Mainz, Germany
| | - Matthias E Bauch
- Institut für Allgemeine Botanik, Johannes Gutenberg-Universität, 55099, Mainz, Germany
| | - Yvonne Pörschke
- Institut für Allgemeine Botanik, Johannes Gutenberg-Universität, 55099, Mainz, Germany
| | - Martin Lohr
- Institut für Allgemeine Botanik, Johannes Gutenberg-Universität, 55099, Mainz, Germany
| |
Collapse
|
16
|
Halsey KH, Milligan AJ, Behrenfeld MJ. Contrasting strategies of photosynthetic energy utilization drive lifestyle strategies in ecologically important picoeukaryotes. Metabolites 2014; 4:260-80. [PMID: 24957026 PMCID: PMC4101506 DOI: 10.3390/metabo4020260] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2014] [Revised: 04/09/2014] [Accepted: 04/23/2014] [Indexed: 11/16/2022] Open
Abstract
The efficiency with which absorbed light is converted to net growth is a key property for estimating global carbon production. We previously showed that, despite considerable evolutionary distance, Dunaliella tertiolecta (Chlorophyceae) and Thalassiosira weissflogii (Bacillariophyceae) share a common strategy of photosynthetic energy utilization and nearly identical light energy conversion efficiencies. These findings suggested that a single model might be appropriate for describing relationships between measures of phytoplankton production. This conclusion was further evaluated for Ostreococcus tauri RCC1558 and Micromonas pusilla RCC299 (Chlorophyta, Prasinophyceae), two picoeukaryotes with contrasting geographic distributions and swimming abilities. Nutrient-dependent photosynthetic efficiencies in O. tauri were similar to the previously studied larger algae. Specifically, absorption-normalized gross oxygen and carbon production and net carbon production were independent of nutrient limited growth rate. In contrast, all measures of photosynthetic efficiency were strongly dependent on nutrient availability in M. pusilla. This marked difference was accompanied by a diminished relationship between Chla:C and nutrient limited growth rate and a remarkably greater efficiency of gross-to-net energy conversion than the other organisms studied. These results suggest that the cost-benefit of decoupling pigment concentration from nutrient availability enables motile organisms to rapidly exploit more frequent encounters with micro-scale nutrient patches in open ocean environments.
Collapse
Affiliation(s)
- Kimberly H Halsey
- Department of Microbiology, Oregon State University; 220 Nash Hall, Corvallis, OR 97330, USA.
| | - Allen J Milligan
- Department of Botany and Plant Pathology, Oregon State University; 2082 Cordley hall, Corvallis, OR 97330, USA.
| | - Michael J Behrenfeld
- Department of Botany and Plant Pathology, Oregon State University; 2082 Cordley hall, Corvallis, OR 97330, USA.
| |
Collapse
|
17
|
Yamada N, Tanaka A, Horiguchi T. cPPB-aE is discovered from photosynthetic benthic dinoflagellates. JOURNAL OF PHYCOLOGY 2014; 50:101-107. [PMID: 26988011 DOI: 10.1111/jpy.12135] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2013] [Accepted: 09/24/2013] [Indexed: 06/05/2023]
Abstract
Although chlorophyll degradation pathways in higher plants have been well studied, little is known about the mechanisms of chlorophyll degradation in microalgae. In this article, we report the occurrence of a chlorophyll a derivative that has never been discovered in photosynthetic organisms. This chlorophyll derivative emits no fluorescence and has a peculiar absorbance peak at 425, 451, 625, and 685 nm. From these features, it was identified as 13(2) ,17(3) -cyclopheophorbide a enol (cPPB-aE), reported as a degradation product of chlorophyll a derived from prey algal cells in heterotrophic protists. We discovered cPPB-aE in six benthic photosynthetic dinoflagellates that are phylogenetically separated into four clades based on SSU rDNA molecular phylogeny. This is the first report of this chlorophyll derivative in photosynthetic organisms and we suggest that the derivative is used to quench excess light energy.
Collapse
Affiliation(s)
- Norico Yamada
- Department of Natural History Sciences, Graduate School of Science, Hokkaido University, Sapporo 060-0810, Japan
| | - Ayumi Tanaka
- Institute of Low Temperature Science, Hokkaido University, Sapporo 060-0819, Japan
| | - Takeo Horiguchi
- Department of Natural History Sciences, Faculty of Science, Hokkaido University, Sapporo 060-0810, Japan
| |
Collapse
|
18
|
Pittera J, Humily F, Thorel M, Grulois D, Garczarek L, Six C. Connecting thermal physiology and latitudinal niche partitioning in marine Synechococcus. ISME JOURNAL 2014; 8:1221-36. [PMID: 24401861 DOI: 10.1038/ismej.2013.228] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2013] [Revised: 11/15/2013] [Accepted: 11/16/2013] [Indexed: 01/05/2023]
Abstract
Marine Synechococcus cyanobacteria constitute a monophyletic group that displays a wide latitudinal distribution, ranging from the equator to the polar fronts. Whether these organisms are all physiologically adapted to stand a large temperature gradient or stenotherms with narrow growth temperature ranges has so far remained unexplored. We submitted a panel of six strains, isolated along a gradient of latitude in the North Atlantic Ocean, to long- and short-term variations of temperature. Upon a downward shift of temperature, the strains showed strikingly distinct resistance, seemingly related to their latitude of isolation, with tropical strains collapsing while northern strains were capable of growing. This behaviour was associated to differential photosynthetic performances. In the tropical strains, the rapid photosystem II inactivation and the decrease of the antioxydant β-carotene relative to chl a suggested a strong induction of oxidative stress. These different responses were related to the thermal preferenda of the strains. The northern strains could grow at 10 °C while the other strains preferred higher temperatures. In addition, we pointed out a correspondence between strain isolation temperature and phylogeny. In particular, clades I and IV laboratory strains were all collected in the coldest waters of the distribution area of marine Synechococus. We, however, show that clade I Synechococcus exhibit different levels of adaptation, which apparently reflect their location on the latitudinal temperature gradient. This study reveals the existence of lineages of marine Synechococcus physiologically specialised in different thermal niches, therefore suggesting the existence of temperature ecotypes within the marine Synechococcus radiation.
Collapse
Affiliation(s)
- Justine Pittera
- 1] University Pierre and Marie Curie (Paris 06), UMR 7144 Adaptation and Diversity in Marine Environments, Marine Phototrophic Procaryotes (MaPP) Team, Station Biologique de Roscoff, Place Georges Teissier, CS 90074, Roscoff cedex, France [2] Centre National de la Recherche Scientifique, UMR 7144 Adaptation and Diversity in Marine Environments, Oceanic Plankton Group, Station Biologique de Roscoff, Place Georges Teissier, CS 90074, Roscoff cedex, France
| | - Florian Humily
- 1] University Pierre and Marie Curie (Paris 06), UMR 7144 Adaptation and Diversity in Marine Environments, Marine Phototrophic Procaryotes (MaPP) Team, Station Biologique de Roscoff, Place Georges Teissier, CS 90074, Roscoff cedex, France [2] Centre National de la Recherche Scientifique, UMR 7144 Adaptation and Diversity in Marine Environments, Oceanic Plankton Group, Station Biologique de Roscoff, Place Georges Teissier, CS 90074, Roscoff cedex, France
| | - Maxine Thorel
- University of Caen-Basse Normandie et Centre National de la Recherche Scientifique, Institut d'Ecologie et d'Environnement, FRE 3484 Biologie des Mollusques Marins et des Ecosystèmes associés, Caen, France
| | - Daphné Grulois
- 1] University Pierre and Marie Curie (Paris 06), UMR 7144 Adaptation and Diversity in Marine Environments, Marine Phototrophic Procaryotes (MaPP) Team, Station Biologique de Roscoff, Place Georges Teissier, CS 90074, Roscoff cedex, France [2] Centre National de la Recherche Scientifique, UMR 7144 Adaptation and Diversity in Marine Environments, Oceanic Plankton Group, Station Biologique de Roscoff, Place Georges Teissier, CS 90074, Roscoff cedex, France
| | - Laurence Garczarek
- 1] University Pierre and Marie Curie (Paris 06), UMR 7144 Adaptation and Diversity in Marine Environments, Marine Phototrophic Procaryotes (MaPP) Team, Station Biologique de Roscoff, Place Georges Teissier, CS 90074, Roscoff cedex, France [2] Centre National de la Recherche Scientifique, UMR 7144 Adaptation and Diversity in Marine Environments, Oceanic Plankton Group, Station Biologique de Roscoff, Place Georges Teissier, CS 90074, Roscoff cedex, France
| | - Christophe Six
- 1] University Pierre and Marie Curie (Paris 06), UMR 7144 Adaptation and Diversity in Marine Environments, Marine Phototrophic Procaryotes (MaPP) Team, Station Biologique de Roscoff, Place Georges Teissier, CS 90074, Roscoff cedex, France [2] Centre National de la Recherche Scientifique, UMR 7144 Adaptation and Diversity in Marine Environments, Oceanic Plankton Group, Station Biologique de Roscoff, Place Georges Teissier, CS 90074, Roscoff cedex, France
| |
Collapse
|
19
|
Finazzi G, Minagawa J. High Light Acclimation in Green Microalgae. ADVANCES IN PHOTOSYNTHESIS AND RESPIRATION 2014. [DOI: 10.1007/978-94-017-9032-1_21] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
|
20
|
Noisette F, Duong G, Six C, Davoult D, Martin S. Effects of elevated pCO2 on the metabolism of a temperate rhodolith Lithothamnion corallioides grown under different temperatures. JOURNAL OF PHYCOLOGY 2013; 49:746-757. [PMID: 27007207 DOI: 10.1111/jpy.12085] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2012] [Accepted: 05/08/2013] [Indexed: 06/05/2023]
Abstract
Coralline algae are considered among the most sensitive species to near future ocean acidification. We tested the effects of elevated pCO2 on the metabolism of the free-living coralline alga Lithothamnion corallioides ("maerl") and the interactions with changes in temperature. Specimens were collected in North Brittany (France) and grown for 3 months at pCO2 of 380 (ambient pCO2 ), 550, 750, and 1000 μatm (elevated pCO2 ) and at successive temperatures of 10°C (ambient temperature in winter), 16°C (ambient temperature in summer), and 19°C (ambient temperature in summer +3°C). At each temperature, gross primary production, respiration (oxygen flux), and calcification (alkalinity flux) rates were assessed in the light and dark. Pigments were determined by HPLC. Chl a, carotene, and zeaxanthin were the three major pigments found in L. corallioides thalli. Elevated pCO2 did not affect pigment content while temperature slightly decreased zeaxanthin and carotene content at 10°C. Gross production was not affected by temperature but was significantly affected by pCO2 with an increase between 380 and 550 μatm. Light, dark, and diel (24 h) calcification rates strongly decreased with increasing pCO2 regardless of the temperature. Although elevated pCO2 only slightly affected gross production in L. corallioides, diel net calcification was reduced by up to 80% under the 1,000 μatm treatment. Our findings suggested that near future levels of CO2 will have profound consequences for carbon and carbonate budgets in rhodolith beds and for the sustainability of these habitats.
Collapse
Affiliation(s)
- Fanny Noisette
- UPMC Univ. Paris 6, CNRS, UMR 7144, Station Biologique de Roscoff, Place Georges Teissier, Roscoff Cedex, 29688, France
| | - Gwendoline Duong
- UPMC Univ. Paris 6, CNRS, UMR 7144, Station Biologique de Roscoff, Place Georges Teissier, Roscoff Cedex, 29688, France
| | - Christophe Six
- UPMC Univ. Paris 6, CNRS, UMR 7144, Station Biologique de Roscoff, Place Georges Teissier, Roscoff Cedex, 29688, France
| | - Dominique Davoult
- UPMC Univ. Paris 6, CNRS, UMR 7144, Station Biologique de Roscoff, Place Georges Teissier, Roscoff Cedex, 29688, France
| | - Sophie Martin
- UPMC Univ. Paris 6, CNRS, UMR 7144, Station Biologique de Roscoff, Place Georges Teissier, Roscoff Cedex, 29688, France
| |
Collapse
|
21
|
Kunugi M, Takabayashi A, Tanaka A. Evolutionary changes in chlorophyllide a oxygenase (CAO) structure contribute to the acquisition of a new light-harvesting complex in micromonas. J Biol Chem 2013; 288:19330-41. [PMID: 23677999 DOI: 10.1074/jbc.m113.462663] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Chlorophyll b is found in photosynthetic prokaryotes and primary and secondary endosymbionts, although their light-harvesting systems are quite different. Chlorophyll b is synthesized from chlorophyll a by chlorophyllide a oxygenase (CAO), which is a Rieske-mononuclear iron oxygenase. Comparison of the amino acid sequences of CAO among photosynthetic organisms elucidated changes in the domain structures of CAO during evolution. However, the evolutionary relationship between the light-harvesting system and the domain structure of CAO remains unclear. To elucidate this relationship, we investigated the CAO structure and the pigment composition of chlorophyll-protein complexes in the prasinophyte Micromonas. The Micromonas CAO is composed of two genes, MpCAO1 and MpCAO2, that possess Rieske and mononuclear iron-binding motifs, respectively. Only when both genes were introduced into the chlorophyll b-less Arabidopsis mutant (ch1-1) was chlorophyll b accumulated, indicating that cooperation between the two subunits is required to synthesize chlorophyll b. Although Micromonas has a characteristic light-harvesting system in which chlorophyll b is incorporated into the core antennas of reaction centers, chlorophyll b was also incorporated into the core antennas of reaction centers of the Arabidopsis transformants that contained the two Micromonas CAO proteins. Based on these results, we discuss the evolutionary relationship between the structures of CAO and light-harvesting systems.
Collapse
Affiliation(s)
- Motoshi Kunugi
- Institute of Low Temperature Science, Hokkaido University, N19 W8 Kita-Ku, Japan
| | | | | |
Collapse
|
22
|
Zhang X, Ye N, Liang C, Mou S, Fan X, Xu J, Xu D, Zhuang Z. De novo sequencing and analysis of the Ulva linza transcriptome to discover putative mechanisms associated with its successful colonization of coastal ecosystems. BMC Genomics 2012; 13:565. [PMID: 23098051 PMCID: PMC3532339 DOI: 10.1186/1471-2164-13-565] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2011] [Accepted: 10/20/2012] [Indexed: 12/27/2022] Open
Abstract
BACKGROUND The green algal genus Ulva Linnaeus (Ulvaceae, Ulvales, Chlorophyta) is well known for its wide distribution in marine, freshwater, and brackish environments throughout the world. The Ulva species are also highly tolerant of variations in salinity, temperature, and irradiance and are the main cause of green tides, which can have deleterious ecological effects. However, limited genomic information is currently available in this non-model and ecologically important species. Ulva linza is a species that inhabits bedrock in the mid to low intertidal zone, and it is a major contributor to biofouling. Here, we presented the global characterization of the U. linza transcriptome using the Roche GS FLX Titanium platform, with the aim of uncovering the genomic mechanisms underlying rapid and successful colonization of the coastal ecosystems. RESULTS De novo assembly of 382,884 reads generated 13,426 contigs with an average length of 1,000 bases. Contiguous sequences were further assembled into 10,784 isotigs with an average length of 1,515 bases. A total of 304,101 reads were nominally identified by BLAST; 4,368 isotigs were functionally annotated with 13,550 GO terms, and 2,404 isotigs having enzyme commission (EC) numbers were assigned to 262 KEGG pathways. When compared with four other full sequenced green algae, 3,457 unique isotigs were found in U. linza and 18 conserved in land plants. In addition, a specific photoprotective mechanism based on both LhcSR and PsbS proteins and a C4-like carbon-concentrating mechanism were found, which may help U. linza survive stress conditions. At least 19 transporters for essential inorganic nutrients (i.e., nitrogen, phosphorus, and sulphur) were responsible for its ability to take up inorganic nutrients, and at least 25 eukaryotic cytochrome P450s, which is a higher number than that found in other algae, may be related to their strong allelopathy. Multi-origination of the stress related proteins, such as glutamate dehydrogenase, superoxide dismutases, ascorbate peroxidase, catalase and heat-shock proteins, may also contribute to colonization of U. linza under stress conditions. CONCLUSIONS The transcriptome of U. linza uncovers some potential genomic mechanisms that might explain its ability to rapidly and successfully colonize coastal ecosystems, including the land-specific genes; special photoprotective mechanism based on both LhcSR and PsbS; development of C4-like carbon-concentrating mechanisms; muti-origin transporters for essential inorganic nutrients; multiple and complex P450s; and glutamate dehydrogenase, superoxide dismutases, ascorbate peroxidase, catalase, and heat-shock proteins that are related to stress resistance.
Collapse
Affiliation(s)
- Xiaowen Zhang
- Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao, 266071, China
| | - Naihao Ye
- Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao, 266071, China
| | - Chengwei Liang
- Qingdao University of Science > Technology, Qingdao, 266042, China
| | - Shanli Mou
- Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao, 266071, China
| | - Xiao Fan
- Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao, 266071, China
| | - Jianfang Xu
- Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao, 266071, China
- Key Laboratory of Marine Bioactive Substance, The First Institute of Oceanography, State Oceanic administration (SOA), Qingdao, 266061, China
| | - Dong Xu
- Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao, 266071, China
| | - Zhimeng Zhuang
- Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao, 266071, China
| |
Collapse
|
23
|
Light Stress Proteins in Viruses, Cyanobacteria and Photosynthetic Eukaryota. PHOTOSYNTHESIS 2012. [DOI: 10.1007/978-94-007-1579-0_14] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/10/2023]
|
24
|
The Extended Light-Harvesting Complex (LHC) Protein Superfamily: Classification and Evolutionary Dynamics. FUNCTIONAL GENOMICS AND EVOLUTION OF PHOTOSYNTHETIC SYSTEMS 2012. [DOI: 10.1007/978-94-007-1533-2_11] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
|
25
|
Alboresi A, Gerotto C, Cazzaniga S, Bassi R, Morosinotto T. A red-shifted antenna protein associated with photosystem II in Physcomitrella patens. J Biol Chem 2011; 286:28978-28987. [PMID: 21705318 DOI: 10.1074/jbc.m111.226126] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Antenna systems of plants and green algae are made up of pigment-protein complexes belonging to the light-harvesting complex (LHC) multigene family. LHCs increase the light-harvesting cross-section of photosystems I and II and catalyze photoprotective reactions that prevent light-induced damage in an oxygenic environment. The genome of the moss Physcomitrella patens contains two genes encoding LHCb9, a new antenna protein that bears an overall sequence similarity to photosystem II antenna proteins but carries a specific motif typical of photosystem I antenna proteins. This consists of the presence of an asparagine residue as a ligand for Chl 603 (A5) chromophore rather than a histidine, the common ligand in all other LHCbs. Asparagine as a Chl 603 (A5) ligand generates red-shifted spectral forms associated with photosystem I rather than with photosystem II, suggesting that in P. patens, the energy landscape of photosystem II might be different with respect to that of most green algae and plants. In this work, we show that the in vitro refolded LHCb9-pigment complexes carry a red-shifted fluorescence emission peak, different from all other known photosystem II antenna proteins. By using a specific antibody, we localized LHCb9 within PSII supercomplexes in the thylakoid membranes. This is the first report of red-shifted spectral forms in a PSII antenna system, suggesting that this biophysical feature might have a special role either in optimization of light use efficiency or in photoprotection in the specific environmental conditions experienced by this moss.
Collapse
Affiliation(s)
- Alessandro Alboresi
- Dipartimento di Biotecnologie, Università di Verona, Strada le Grazie 15, 37134 Verona, Italy
| | - Caterina Gerotto
- Dipartimento di Biologia, Università di Padova, Via Ugo Bassi 58 B, 35121 Padova, Italy, and
| | - Stefano Cazzaniga
- Dipartimento di Biotecnologie, Università di Verona, Strada le Grazie 15, 37134 Verona, Italy
| | - Roberto Bassi
- Dipartimento di Biotecnologie, Università di Verona, Strada le Grazie 15, 37134 Verona, Italy,; ICG-3, Phytosphäre Forschungszentrum Jülich, 52425 Jülich, Germany.
| | - Tomas Morosinotto
- Dipartimento di Biologia, Università di Padova, Via Ugo Bassi 58 B, 35121 Padova, Italy, and
| |
Collapse
|
26
|
Ballottari M, Girardon J, Dall'osto L, Bassi R. Evolution and functional properties of photosystem II light harvesting complexes in eukaryotes. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2011; 1817:143-57. [PMID: 21704018 DOI: 10.1016/j.bbabio.2011.06.005] [Citation(s) in RCA: 118] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2011] [Revised: 06/08/2011] [Accepted: 06/08/2011] [Indexed: 11/28/2022]
Abstract
Photoautotrophic organisms, the major agent of inorganic carbon fixation into biomass, convert light energy into chemical energy. The first step of photosynthesis consists of the absorption of solar energy by pigments binding protein complexes named photosystems. Within photosystems, a family of proteins called Light Harvesting Complexes (LHC), responsible for light harvesting and energy transfer to reaction centers, has evolved along with eukaryotic organisms. Besides light absorption, these proteins catalyze photoprotective reactions which allowed functioning of oxygenic photosynthetic machinery in the increasingly oxidant environment. In this work we review current knowledge of LHC proteins serving Photosystem II. Balance between light harvesting and photoprotection is critical in Photosystem II, due to the lower quantum efficiency as compared to Photosystem I. In particular, we focus on the role of each antenna complex in light harvesting, energy transfer, scavenging of reactive oxygen species, chlorophyll triplet quenching and thermal dissipation of excess energy. This article is part of a Special Issue entitled: Photosystem II.
Collapse
Affiliation(s)
- Matteo Ballottari
- Dipartimento di Biotecnologie, Università di Verona, Ca' Vignal 1, Strada le Grazie 15, I-37134 Verona, Italy
| | | | | | | |
Collapse
|
27
|
Cock JM, Coelho SM. Algal models in plant biology. JOURNAL OF EXPERIMENTAL BOTANY 2011; 62:2425-2430. [PMID: 21576398 DOI: 10.1093/jxb/err117] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Affiliation(s)
- J Mark Cock
- UPMC Univ. Paris 06, The Marine Plants and Biomolecules Laboratory, UMR 7139, Station Biologique de Roscoff, Place Georges Teissier, F-29682 Roscoff, France.
| | | |
Collapse
|
28
|
Genome diversity in the smallest marine photosynthetic eukaryotes. Res Microbiol 2011; 162:570-7. [PMID: 21540104 DOI: 10.1016/j.resmic.2011.04.005] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2011] [Accepted: 03/02/2011] [Indexed: 02/04/2023]
Abstract
Unicellular algae of the class Mamiellophyceae are widespread in our oceans and their apparent uniformity conceals an impressive array of biologically distinct species. Each of the five complete genomes analysed so far reveals densely packed coding sequences, with strong evolutionary divergence from its nearest phylogenetically defined neighbours. These species lie at the base of the green lineage, but various metabolic processes reflect their marine life-styles and distinguish them from land plants, including a high proportion of selenoprotein enzymes and C4 photosynthesis. They all possess two unusual chromosomes, with lower GC content and atypical gene content, whose function so far remains enigmatic.
Collapse
|
29
|
Bailleul B, Cardol P, Breyton C, Finazzi G. Electrochromism: a useful probe to study algal photosynthesis. PHOTOSYNTHESIS RESEARCH 2010; 106:179-89. [PMID: 20632109 DOI: 10.1007/s11120-010-9579-z] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2010] [Accepted: 06/23/2010] [Indexed: 05/07/2023]
Abstract
In photosynthesis, electron transfer along the photosynthetic chain results in a vectorial transfer of protons from the stroma to the lumenal space of the thylakoids. This promotes the generation of an electrochemical proton gradient (Δμ(H)(+)), which comprises a gradient of electric potential (ΔΨ) and of proton concentration (ΔpH). The Δμ(H)(+) has a central role in the photosynthetic process, providing the energy source for ATP synthesis. It is also involved in many regulatory mechanisms. The ΔpH modulates the rate of electron transfer and triggers deexcitation of excess energy within the light harvesting complexes. The ΔΨ is required for metabolite and protein transport across the membranes. Its presence also induces a shift in the absorption spectra of some photosynthetic pigments, resulting in the so-called ElectroChromic Shift (ECS). In this review, we discuss the characteristic features of the ECS, and illustrate possible applications for the study of photosynthetic processes in vivo.
Collapse
Affiliation(s)
- Benjamin Bailleul
- UMR 7141, Centre National de la Recherche Scientifique, Institut de Biologie Physico-Chimique, Université Pierre et Marie Curie, 75005 Paris, France.
| | | | | | | |
Collapse
|
30
|
Neilson JAD, Durnford DG. Structural and functional diversification of the light-harvesting complexes in photosynthetic eukaryotes. PHOTOSYNTHESIS RESEARCH 2010; 106:57-71. [PMID: 20596891 DOI: 10.1007/s11120-010-9576-2] [Citation(s) in RCA: 88] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2010] [Accepted: 06/16/2010] [Indexed: 05/25/2023]
Abstract
Eukaryotes acquired photosynthetic metabolism over a billion years ago, and during that time the light-harvesting antennae have undergone significant structural and functional divergence. The antenna systems are generally used to harvest and transfer excitation energy into the reaction centers to drive photosynthesis, but also have the dual role of energy dissipation. Phycobilisomes formed the first antenna system in oxygenic photoautotrophs, and this soluble protein complex continues to be the dominant antenna in extant cyanobacteria, glaucophytes, and red algae. However, phycobilisomes were lost multiple times during eukaryotic evolution in favor of a thylakoid membrane-integral light-harvesting complex (LHC) antenna system found in the majority of eukaryotic taxa. While photosynthesis spread across different eukaryotic kingdoms via endosymbiosis, the antenna systems underwent extensive modification as photosynthetic groups optimized their light-harvesting capacity and ability to acclimate to changing environmental conditions. This review discusses the different classes of LHCs within photosynthetic eukaryotes and examines LHC diversification in different groups in a structural and functional context.
Collapse
Affiliation(s)
- Jonathan A D Neilson
- Department of Biology, University of New Brunswick, Fredericton, NB E3B 5A3, Canada
| | | |
Collapse
|
31
|
Busch A, Hippler M. The structure and function of eukaryotic photosystem I. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2010; 1807:864-77. [PMID: 20920463 DOI: 10.1016/j.bbabio.2010.09.009] [Citation(s) in RCA: 99] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2010] [Revised: 09/20/2010] [Accepted: 09/28/2010] [Indexed: 12/27/2022]
Abstract
Eukaryotic photosystem I consists of two functional moieties: the photosystem I core, harboring the components for the light-driven charge separation and the subsequent electron transfer, and the peripheral light-harvesting complex (LHCI). While the photosystem I-core remained highly conserved throughout the evolution, with the exception of the oxidizing side of photosystem I, the LHCI complex shows a high degree of variability in size, subunits composition and bound pigments, which is due to the large variety of different habitats photosynthetic organisms dwell in. Besides summarizing the most current knowledge on the photosystem I-core structure, we will discuss the composition and structure of the LHCI complex from different eukaryotic organisms, both from the red and the green clade. Furthermore, mechanistic insights into electron transfer between the donor and acceptor side of photosystem I and its soluble electron transfer carrier proteins will be given. This article is part of a Special Issue entitled: Regulation of Electron Transport in Chloroplasts.
Collapse
Affiliation(s)
- Andreas Busch
- Department of Plant Biology and Biotechnology, Faculty of Life Sciences, University of Copenhagen, Thorvaldsensvej 40, DK-1871 Frederiksberg C, Denmark.
| | | |
Collapse
|
32
|
Finazzi G, Moreau H, Bowler C. Genomic insights into photosynthesis in eukaryotic phytoplankton. TRENDS IN PLANT SCIENCE 2010; 15:565-572. [PMID: 20800533 DOI: 10.1016/j.tplants.2010.07.004] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2010] [Revised: 07/21/2010] [Accepted: 07/22/2010] [Indexed: 05/29/2023]
Abstract
The evolution of photosynthesis completely altered the biogeochemistry of our planet and permitted the evolution of more complex multicellular organisms. Curiously, terrestrial photosynthesis is carried out largely by green algae and their descendents the higher plants, whereas in the ocean the most abundant photosynthetic eukaryotes are microscopic and have red algal affiliations. Although primary productivity is approximately equal between the land and the ocean, the marine microbes represent less than 1% of the photosynthetic biomass found on land. This review focuses on this highly successful and diverse group of organisms collectively known as phytoplankton and reviews how insights from whole genome analyses have improved our understanding of the novel innovations employed by them to maximize photosynthetic efficiency in variable light environments.
Collapse
Affiliation(s)
- Giovanni Finazzi
- Laboratoire de Physiologie Vegetale et Cellulaire, UMR 5168 Centre National de la Recherche Scientifique/Commissariat à l'énergie atomique et aux énergies alternatives/Université Joseph Fourier, CEA Grenoble, 17 rue des Martyrs, 38054 Grenoble, France
| | | | | |
Collapse
|
33
|
Component interactions, regulation and mechanisms of chloroplast signal recognition particle-dependent protein transport. Eur J Cell Biol 2010; 89:965-73. [PMID: 20709425 DOI: 10.1016/j.ejcb.2010.06.020] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
The chloroplast proteome comprises nuclear- and plastome-encoded proteins. In order to function correctly these proteins must be transported, either cotranslationally or posttranslationally, to their final destination in the chloroplast. Here the chloroplast signal recognition particle (cpSRP) which is present in two different stromal pools plays an essential role. On the one hand, the conserved 54kDa subunit (cpSRP54) is associated with 70S ribosomes to function in the cotranslational transport of the plastid-encoded thylakoid membrane protein D1. On the other hand, the cpSRP consists of cpSRP54 and a unique 43kDa subunit (cpSRP43) and facilitates the transport of nuclear-encoded light-harvesting chlorophyll-binding proteins (LHCPs), the most abundant membrane proteins of the thylakoids. In addition to cpSRP, the cpSRP receptor cpFtsY and the thylakoid membrane protein Alb3 are required for posttranslational LHCP integration in a GTP-dependent manner. In contrast to the universally conserved cytosolic SRP, the chloroplast SRP of higher plants lacks an SRP-RNA component. Interestingly, cpSRP-RNA genes have been identified in the plastome of lower plants, indicating that their cpSRP structure resembles the cytosolic SRP.
Collapse
|
34
|
Swingley WD, Iwai M, Chen Y, Ozawa SI, Takizawa K, Takahashi Y, Minagawa J. Characterization of photosystem I antenna proteins in the prasinophyte Ostreococcus tauri. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2010; 1797:1458-64. [PMID: 20457235 DOI: 10.1016/j.bbabio.2010.04.017] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2009] [Revised: 04/13/2010] [Accepted: 04/26/2010] [Indexed: 11/17/2022]
Abstract
Prasinophyceae are a broad class of early-branching eukaryotic green algae. These picophytoplankton are found ubiquitously throughout the ocean and contribute considerably to global carbon-fixation. Ostreococcus tauri, as the first sequenced prasinophyte, is a model species for studying the functional evolution of light-harvesting systems in photosynthetic eukaryotes. In this study we isolated and characterized O. tauri pigment-protein complexes. Two photosystem I (PSI) fractions were obtained by sucrose density gradient centrifugation in addition to free light-harvesting complex (LHC) fraction and photosystem II (PSII) core fractions. The smaller PSI fraction contains the PSI core proteins, LHCI, which are conserved in all green plants, Lhcp1, a prasinophyte-specific LHC protein, and the minor, monomeric LHCII proteins CP26 and CP29. The larger PSI fraction contained the same antenna proteins as the smaller, with the addition of Lhca6 and Lhcp2, and a 30% larger absorption cross-section. When O. tauri was grown under high-light conditions, only the smaller PSI fraction was present. The two PSI preparations were also found to be devoid of the far-red chlorophyll fluorescence (715-730 nm), a signature of PSI in oxygenic phototrophs. These unique features of O. tauri PSI may reflect primitive light-harvesting systems in green plants and their adaptation to marine ecosystems. Possible implications for the evolution of the LHC-superfamily in photosynthetic eukaryotes are discussed.
Collapse
Affiliation(s)
- Wesley D Swingley
- Institute of Low Temperature Science, Hokkaido University, Sapporo 060-0819, Japan
| | | | | | | | | | | | | |
Collapse
|
35
|
Monnier A, Liverani S, Bouvet R, Jesson B, Smith JQ, Mosser J, Corellou F, Bouget FY. Orchestrated transcription of biological processes in the marine picoeukaryote Ostreococcus exposed to light/dark cycles. BMC Genomics 2010; 11:192. [PMID: 20307298 PMCID: PMC2850359 DOI: 10.1186/1471-2164-11-192] [Citation(s) in RCA: 102] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2009] [Accepted: 03/22/2010] [Indexed: 11/22/2022] Open
Abstract
Background Picoeukaryotes represent an important, yet poorly characterized component of marine phytoplankton. The recent genome availability for two species of Ostreococcus and Micromonas has led to the emergence of picophytoplankton comparative genomics. Sequencing has revealed many unexpected features about genome structure and led to several hypotheses on Ostreococcus biology and physiology. Despite the accumulation of genomic data, little is known about gene expression in eukaryotic picophytoplankton. Results We have conducted a genome-wide analysis of gene expression in Ostreococcus tauri cells exposed to light/dark cycles (L/D). A Bayesian Fourier Clustering method was implemented to cluster rhythmic genes according to their expression waveform. In a single L/D condition nearly all expressed genes displayed rhythmic patterns of expression. Clusters of genes were associated with the main biological processes such as transcription in the nucleus and the organelles, photosynthesis, DNA replication and mitosis. Conclusions Light/Dark time-dependent transcription of the genes involved in the main steps leading to protein synthesis (transcription basic machinery, ribosome biogenesis, translation and aminoacid synthesis) was observed, to an unprecedented extent in eukaryotes, suggesting a major input of transcriptional regulations in Ostreococcus. We propose that the diurnal co-regulation of genes involved in photoprotection, defence against oxidative stress and DNA repair might be an efficient mechanism, which protects cells against photo-damage thereby, contributing to the ability of O. tauri to grow under a wide range of light intensities.
Collapse
Affiliation(s)
- Annabelle Monnier
- OUEST-genopole(R)transcriptome platform, IFR 140 GFAS, Faculté de Médecine, 2 avenue du Pr Léon Bernard, Rennes Cedex, France
| | | | | | | | | | | | | | | |
Collapse
|
36
|
|
37
|
Kim J, Smith JJ, Tian L, DellaPenna D. The Evolution and Function of Carotenoid Hydroxylases in Arabidopsis. ACTA ACUST UNITED AC 2009; 50:463-79. [DOI: 10.1093/pcp/pcp005] [Citation(s) in RCA: 142] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
|
38
|
Kim E, Archibald JM. Diversity and Evolution of Plastids and Their Genomes. PLANT CELL MONOGRAPHS 2008. [DOI: 10.1007/978-3-540-68696-5_1] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
|
39
|
Richter CV, Träger C, Schünemann D. Evolutionary substitution of two amino acids in chloroplast SRP54 of higher plants cause its inability to bind SRP RNA. FEBS Lett 2008; 582:3223-9. [PMID: 18755190 DOI: 10.1016/j.febslet.2008.08.014] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2008] [Revised: 08/14/2008] [Accepted: 08/15/2008] [Indexed: 10/21/2022]
Abstract
The chloroplast signal recognition particle (cpSRP) consists of a conserved 54 kDa subunit (cpSRP54) and a unique 43 kDa subunit (cpSRP43) but lacks SRP-RNA, an essential and universally conserved component of cytosolic SRPs. High sequence similarity exists between cpSRP54 and bacterial SRP54 except for a plant-specific C-terminal extension containing the cpSRP43-binding motif. We found that cpSRP54 of higher plants lacks the ability to bind SRP-RNA because of two amino acid substitutions within a region corresponding to the RNA binding domain of cytosolic SRP54, whereas the C-terminal extension does not affect RNA binding. Phylogenetic analysis revealed that these mutations occur in the cpSRP54 homologues of higher plants but not in most algae.
Collapse
Affiliation(s)
- Christine V Richter
- Lehrstuhl für Pflanzenphysiologie, Ruhr-Universität Bochum, 44780 Bochum, Germany
| | | | | |
Collapse
|
40
|
An original adaptation of photosynthesis in the marine green alga Ostreococcus. Proc Natl Acad Sci U S A 2008; 105:7881-6. [PMID: 18511560 DOI: 10.1073/pnas.0802762105] [Citation(s) in RCA: 127] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Adaptation of photosynthesis in marine environment has been examined in two strains of the green, picoeukaryote Ostreococcus: OTH95, a surface/high-light strain, and RCC809, a deep-sea/low-light strain. Differences between the two strains include changes in the light-harvesting capacity, which is lower in OTH95, and in the photoprotection capacity, which is enhanced in OTH95. Furthermore, RCC809 has a reduced maximum rate of O(2) evolution, which is limited by its decreased photosystem I (PSI) level, a possible adaptation to Fe limitation in the open oceans. This decrease is, however, accompanied by a substantial rerouting of the electron flow to establish an H(2)O-to-H(2)O cycle, involving PSII and a potential plastid plastoquinol terminal oxidase. This pathway bypasses electron transfer through the cytochrome b(6)f complex and allows the pumping of "extra" protons into the thylakoid lumen. By promoting the generation of a large DeltapH, it facilitates ATP synthesis and nonphotochemical quenching when RCC809 cells are exposed to excess excitation energy. We propose that the diversion of electrons to oxygen downstream of PSII, but before PSI, reflects a common and compulsory strategy in marine phytoplankton to bypass the constraints imposed by light and/or nutrient limitation and allow successful colonization of the open-ocean marine environment.
Collapse
|
41
|
In silico and biochemical analysis of Physcomitrella patens photosynthetic antenna: identification of subunits which evolved upon land adaptation. PLoS One 2008; 3:e2033. [PMID: 18446222 PMCID: PMC2323573 DOI: 10.1371/journal.pone.0002033] [Citation(s) in RCA: 100] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2008] [Accepted: 03/09/2008] [Indexed: 12/17/2022] Open
Abstract
Background In eukaryotes the photosynthetic antenna system is composed of subunits encoded by the light harvesting complex (Lhc) multigene family. These proteins play a key role in photosynthesis and are involved in both light harvesting and photoprotection. The moss Physcomitrella patens is a member of a lineage that diverged from seed plants early after land colonization and therefore by studying this organism, we may gain insight into adaptations to the aerial environment. Principal Findings In this study, we characterized the antenna protein multigene family in Physcomitrella patens, by sequence analysis as well as biochemical and functional investigations. Sequence identification and analysis showed that some antenna polypeptides, such as Lhcb3 and Lhcb6, are present only in land organisms, suggesting they play a role in adaptation to the sub-aerial environment. Our functional analysis which showed that photo-protective mechanisms in Physcomitrella patens are very similar to those in seed plants fits with this hypothesis. In particular, Physcomitrella patens also activates Non Photochemical Quenching upon illumination, consistent with the detection of an ortholog of the PsbS protein. As a further adaptation to terrestrial conditions, the content of Photosystem I low energy absorbing chlorophylls also increased, as demonstrated by differences in Lhca3 and Lhca4 polypeptide sequences, in vitro reconstitution experiments and low temperature fluorescence spectra. Conclusions This study highlights the role of Lhc family members in environmental adaptation and allowed proteins associated with mechanisms of stress resistance to be identified within this large family.
Collapse
|
42
|
Naumann B, Busch A, Allmer J, Ostendorf E, Zeller M, Kirchhoff H, Hippler M. Comparative quantitative proteomics to investigate the remodeling of bioenergetic pathways under iron deficiency in Chlamydomonas reinhardtii. Proteomics 2008; 7:3964-79. [PMID: 17922516 DOI: 10.1002/pmic.200700407] [Citation(s) in RCA: 140] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The basic question addressed in this study is how energy metabolism is adjusted to cope with iron deficiency in Chlamydomonas reinhardtii. To investigate the impact of iron deficiency on bioenergetic pathways, comparative proteomics was combined with spectroscopic as well as voltametric oxygen measurements to assess protein dynamics linked to functional properties of respiratory and photosynthetic machineries. Although photosynthetic electron transfer is largely compromised under iron deficiency, our quantitative and spectroscopic data revealed that the functional antenna size of photosystem II (PSII) significantly increased. Concomitantly, stress-related chloroplast polypeptides, like 2-cys peroxiredoxin and a stress-inducible light-harvesting protein, LhcSR3, as well as a novel light-harvesting protein and several proteins of unknown function were induced under iron-deprivation. Respiratory oxygen consumption did not decrease and accordingly, polypeptides of respiratory complexes, harboring numerous iron-sulfur clusters, were only slightly diminished or even increased under low iron. Consequently, iron-deprivation induces a transition from photoheterotrophic to primarily heterotrophic metabolism, indicating that a hierarchy for iron allocations within organelles of a single cell exists that is closely linked with the metabolic state of the cell.
Collapse
Affiliation(s)
- Bianca Naumann
- Institute of Plant Biochemistry and Biotechnology, University of Münster, Münster, Germany
| | | | | | | | | | | | | |
Collapse
|
43
|
|
44
|
Waters ER, Rioflorido I. Evolutionary analysis of the small heat shock proteins in five complete algal genomes. J Mol Evol 2007; 65:162-74. [PMID: 17684698 DOI: 10.1007/s00239-006-0223-7] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2006] [Accepted: 04/04/2007] [Indexed: 11/29/2022]
Abstract
Small heat shock proteins (sHSPs) are chaperones that are crucial in the heat shock response but also have important nonstress roles within the cell. sHSPs are found in all three domains of life (Bacteria, Archaea, and Eukarya). These proteins are particularly diverse within land plants and the evolutionary origin of the land plant sHSP families is still an open question. Here we describe the identification of 17 small sHSPs from the complete genome sequences of five diverse algae: Chlamydomonas reinhardtii, Cyanidioschyzon merolae, Ostreococcus lucimarinus, Ostreococcus tauri, and Thalassiosira pseudonana. Our analysis indicates that the number and diversity of algal sHSPs are not correlated with adaptation to extreme conditions. While all of the algal sHSPs identified are members of this large and important superfamily, none of these sHSPs are members of the diverse land plant sHSP families. The evolutionary relationships among the algal sHSPs and homologues from bacteria and other eukaryotes are consistent with the hypothesis that the land plant chloroplast and mitochondrion sHSPs did not originate from the endosymbionts of the chloroplast and mitochondria. In addition the evolutionary history of the sHSPs is very different from that of the HSP70s. Finally, our analysis of the algal sHSPs sequences in light of the known sHSP crystal structures and functional data suggests that the sHSPs possess considerable structural and functional diversity.
Collapse
Affiliation(s)
- Elizabeth R Waters
- Department of Biology, San Diego State University, 5500 Campanile Drive, San Diego, CA 92182-4614, USA.
| | | |
Collapse
|
45
|
Six C, Joubin L, Partensky F, Holtzendorff J, Garczarek L. UV-induced phycobilisome dismantling in the marine picocyanobacterium Synechococcus sp. WH8102. PHOTOSYNTHESIS RESEARCH 2007; 92:75-86. [PMID: 17505911 DOI: 10.1007/s11120-007-9170-4] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2006] [Accepted: 04/07/2007] [Indexed: 05/15/2023]
Abstract
The marine picocyanobacterium Synechococcus sp. WH8102 was submitted to ultraviolet (UV-A and B) radiations and the effects of this stress on reaction center II and phycobilisome integrity were studied using a combination of biochemical, biophysical and molecular biology techniques. Under the UV conditions that were applied (4.3 W m(-2) UV-A and 0.86 W m(-2) UV-B), no significant cell mortality and little chlorophyll degradation occurred during the 5 h time course experiment. However, pulse amplitude modulated (PAM) fluorimetry analyses revealed a rapid photoinactivation of reaction centers II. Indeed, a dramatic decrease of the D1 protein amount was observed, despite a large and rapid increase in the expression level of the psbA gene pool. Our results suggest that D1 protein degradation was accompanied (or followed) by the disruption of the N-terminal domain of the anchor linker polypeptide LCM, which in turn led to the disconnection of the phycobilisome complex from the thylakoid membrane. Furthermore, time course analyses of in vivo fluorescence emission spectra suggested a partial dismantling of phycobilisome rods. This was confirmed by characterization of isolated antenna complexes by SDS-PAGE and immunoblotting analyses which allowed us to locate the disruption site of the rods near the phycoerythrin I-phycoerythrin II junction. In addition, genes encoding phycobilisome components, including alpha-subunits of all phycobiliproteins and phycoerythrin linker polypeptides were all down regulated in response to UV stress. Phycobilisome alteration could be the consequence of direct UV-induced photodamages and/or the result of a protease-mediated process.
Collapse
Affiliation(s)
- Christophe Six
- Station Biologique, UMR 7144 CNRS et Université Pierre et Marie Curie, B.P. 74, 29682, Roscoff cedex, France
| | | | | | | | | |
Collapse
|
46
|
Affiliation(s)
- Michael Y Galperin
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 20894, USA.
| |
Collapse
|
47
|
Derelle E, Ferraz C, Rombauts S, Rouzé P, Worden AZ, Robbens S, Partensky F, Degroeve S, Echeynié S, Cooke R, Saeys Y, Wuyts J, Jabbari K, Bowler C, Panaud O, Piégu B, Ball SG, Ral JP, Bouget FY, Piganeau G, De Baets B, Picard A, Delseny M, Demaille J, Van de Peer Y, Moreau H. Genome analysis of the smallest free-living eukaryote Ostreococcus tauri unveils many unique features. Proc Natl Acad Sci U S A 2006; 103:11647-52. [PMID: 16868079 PMCID: PMC1544224 DOI: 10.1073/pnas.0604795103] [Citation(s) in RCA: 528] [Impact Index Per Article: 29.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2006] [Indexed: 02/06/2023] Open
Abstract
The green lineage is reportedly 1,500 million years old, evolving shortly after the endosymbiosis event that gave rise to early photosynthetic eukaryotes. In this study, we unveil the complete genome sequence of an ancient member of this lineage, the unicellular green alga Ostreococcus tauri (Prasinophyceae). This cosmopolitan marine primary producer is the world's smallest free-living eukaryote known to date. Features likely reflecting optimization of environmentally relevant pathways, including resource acquisition, unusual photosynthesis apparatus, and genes potentially involved in C(4) photosynthesis, were observed, as was downsizing of many gene families. Overall, the 12.56-Mb nuclear genome has an extremely high gene density, in part because of extensive reduction of intergenic regions and other forms of compaction such as gene fusion. However, the genome is structurally complex. It exhibits previously unobserved levels of heterogeneity for a eukaryote. Two chromosomes differ structurally from the other eighteen. Both have a significantly biased G+C content, and, remarkably, they contain the majority of transposable elements. Many chromosome 2 genes also have unique codon usage and splicing, but phylogenetic analysis and composition do not support alien gene origin. In contrast, most chromosome 19 genes show no similarity to green lineage genes and a large number of them are specialized in cell surface processes. Taken together, the complete genome sequence, unusual features, and downsized gene families, make O. tauri an ideal model system for research on eukaryotic genome evolution, including chromosome specialization and green lineage ancestry.
Collapse
Affiliation(s)
- Evelyne Derelle
- Observatoire Océanologique, Laboratoire Arago, Unité Mixte de Recherche 7628, Centre National de la Recherche Scientifique–Université Pierre et Marie Curie-Paris 6, BP44, 66651 Banyuls sur Mer Cedex, France
| | - Conchita Ferraz
- Institut de Génétique Humaine, Unité Propre de Recherche 1142, Centre National de la Recherche Scientifique, 141 Rue de Cardonille, 34396 Montpellier Cedex 5, France
| | - Stephane Rombauts
- Department of Plant Systems Biology, Flanders Interuniversity Institute for Biotechnology and
| | - Pierre Rouzé
- Laboratoire Associé de l’Institut National de la Recherche Agronomique (France), Ghent University, Technologiepark 927, 9052 Ghent, Belgium
| | - Alexandra Z. Worden
- Rosenstiel School of Marine and Atmospheric Science, University of Miami, 4600 Rickenbacker Causeway, Miami, FL 33149
| | - Steven Robbens
- Department of Plant Systems Biology, Flanders Interuniversity Institute for Biotechnology and
| | - Frédéric Partensky
- Station Biologique, Unité Mixte de Recherche 7144, Centre National de la Recherche Scientifique–Université Pierre et Marie Curie-Paris 6, BP74, 29682 Roscoff Cedex, France
| | - Sven Degroeve
- Department of Plant Systems Biology, Flanders Interuniversity Institute for Biotechnology and
- Department of Applied Mathematics, Biometrics and Process Control, Ghent University, Coupure Links 653, 9000 Ghent, Belgium
| | - Sophie Echeynié
- Institut de Génétique Humaine, Unité Propre de Recherche 1142, Centre National de la Recherche Scientifique, 141 Rue de Cardonille, 34396 Montpellier Cedex 5, France
| | - Richard Cooke
- Génome et Développement des Plantes, Unité Mixte de Recherche 5096, Centre National de la Recherche Scientifique–Université de Perpignan, 52, Avenue de Villeneuve, 66860 Perpignan, France
| | - Yvan Saeys
- Department of Plant Systems Biology, Flanders Interuniversity Institute for Biotechnology and
| | - Jan Wuyts
- Department of Plant Systems Biology, Flanders Interuniversity Institute for Biotechnology and
| | - Kamel Jabbari
- Département de Biologie, Formation de Recherche en Evolution 2910, Centre National de la Recherche Scientifique–Ecole Normale Supérieure, 46 Rue d’Ulm, 75230 Paris Cedex 05, France; and
| | - Chris Bowler
- Laboratoire de Chimie Biologique, Unité Mixte de Recherche 8765, Centre National de la Recherche Scientifique–Université Sciences et Technologies de Lille, 59655 Villeneuve d’Ascq, France
| | - Olivier Panaud
- Génome et Développement des Plantes, Unité Mixte de Recherche 5096, Centre National de la Recherche Scientifique–Université de Perpignan, 52, Avenue de Villeneuve, 66860 Perpignan, France
| | - Benoît Piégu
- Génome et Développement des Plantes, Unité Mixte de Recherche 5096, Centre National de la Recherche Scientifique–Université de Perpignan, 52, Avenue de Villeneuve, 66860 Perpignan, France
| | - Steven G. Ball
- Laboratoire de Chimie Biologique, Unité Mixte de Recherche 8765, Centre National de la Recherche Scientifique–Université Sciences et Technologies de Lille, 59655 Villeneuve d’Ascq, France
| | - Jean-Philippe Ral
- Laboratoire de Chimie Biologique, Unité Mixte de Recherche 8765, Centre National de la Recherche Scientifique–Université Sciences et Technologies de Lille, 59655 Villeneuve d’Ascq, France
| | - François-Yves Bouget
- Observatoire Océanologique, Laboratoire Arago, Unité Mixte de Recherche 7628, Centre National de la Recherche Scientifique–Université Pierre et Marie Curie-Paris 6, BP44, 66651 Banyuls sur Mer Cedex, France
| | - Gwenael Piganeau
- Observatoire Océanologique, Laboratoire Arago, Unité Mixte de Recherche 7628, Centre National de la Recherche Scientifique–Université Pierre et Marie Curie-Paris 6, BP44, 66651 Banyuls sur Mer Cedex, France
| | - Bernard De Baets
- Department of Applied Mathematics, Biometrics and Process Control, Ghent University, Coupure Links 653, 9000 Ghent, Belgium
| | - André Picard
- Observatoire Océanologique, Laboratoire Arago, Unité Mixte de Recherche 7628, Centre National de la Recherche Scientifique–Université Pierre et Marie Curie-Paris 6, BP44, 66651 Banyuls sur Mer Cedex, France
| | - Michel Delseny
- Génome et Développement des Plantes, Unité Mixte de Recherche 5096, Centre National de la Recherche Scientifique–Université de Perpignan, 52, Avenue de Villeneuve, 66860 Perpignan, France
| | - Jacques Demaille
- Institut de Génétique Humaine, Unité Propre de Recherche 1142, Centre National de la Recherche Scientifique, 141 Rue de Cardonille, 34396 Montpellier Cedex 5, France
| | - Yves Van de Peer
- Department of Plant Systems Biology, Flanders Interuniversity Institute for Biotechnology and
| | - Hervé Moreau
- Observatoire Océanologique, Laboratoire Arago, Unité Mixte de Recherche 7628, Centre National de la Recherche Scientifique–Université Pierre et Marie Curie-Paris 6, BP44, 66651 Banyuls sur Mer Cedex, France
| |
Collapse
|
48
|
Everroad C, Six C, Partensky F, Thomas JC, Holtzendorff J, Wood AM. Biochemical bases of type IV chromatic adaptation in marine Synechococcus spp. J Bacteriol 2006; 188:3345-56. [PMID: 16621829 PMCID: PMC1447437 DOI: 10.1128/jb.188.9.3345-3356.2006] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Chromatic adaptation (CA) in cyanobacteria has provided a model system for the study of the environmental control of photophysiology for several decades. All forms of CA that have been examined so far (types II and III) involve changes in the relative contents of phycoerythrin (PE) and/or phycocyanin when cells are shifted from red to green light and vice versa. However, the chromophore compositions of these polypeptides are not altered. Some marine Synechococcus species strains, which possess two PE forms (PEI and PEII), carry out another type of CA (type IV), occurring during shifts from blue to green or white light. Two chromatically adapting strains of marine Synechococcus recently isolated from the Gulf of Mexico were utilized to elucidate the mechanism of type IV CA. During this process, no change in the relative contents of PEI and PEII was observed. Instead, the ratio of the two chromophores bound to PEII, phycourobilin and phycoerythrobilin, is high under blue light and low under white light. Mass spectroscopy analyses of isolated PEII alpha- and beta-subunits show that there is a single PEII protein type under all light climates. The CA process seems to specifically affect the chromophorylation of the PEII (and possibly PEI) alpha chain. We propose a likely process for type IV CA, which involves the enzymatic activity of one or several phycobilin lyases and/or lyase-isomerases differentially controlled by the ambient light quality. Phylogenetic analyses based on the 16S rRNA gene confirm that type IV CA is not limited to a single clade of marine Synechococcus.
Collapse
Affiliation(s)
- Craig Everroad
- Center for Ecology and Evolution, Department of Biology, University of Oregon, Eugene, Oregon 97403, USA
| | | | | | | | | | | |
Collapse
|