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Rathbone HW, Laos AJ, Michie KA, Iranmanesh H, Biazik J, Goodchild SC, Thordarson P, Green BR, Curmi PMG. Molecular dissection of the soluble photosynthetic antenna from the cryptophyte alga Hemiselmis andersenii. Commun Biol 2023; 6:1158. [PMID: 37957226 PMCID: PMC10643455 DOI: 10.1038/s42003-023-05508-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2023] [Accepted: 10/25/2023] [Indexed: 11/15/2023] Open
Abstract
Cryptophyte algae have a unique phycobiliprotein light-harvesting antenna that fills a spectral gap in chlorophyll absorption from photosystems. However, it is unclear how the antenna transfers energy efficiently to these photosystems. We show that the cryptophyte Hemiselmis andersenii expresses an energetically complex antenna comprising three distinct spectrotypes of phycobiliprotein, each composed of two αβ protomers but with different quaternary structures arising from a diverse α subunit family. We report crystal structures of the major phycobiliprotein from each spectrotype. Two-thirds of the antenna consists of open quaternary form phycobiliproteins acting as primary photon acceptors. These are supplemented by a newly discovered open-braced form (~15%), where an insertion in the α subunit produces ~10 nm absorbance red-shift. The final components (~15%) are closed forms with a long wavelength spectral feature due to substitution of a single chromophore. This chromophore is present on only one β subunit where asymmetry is dictated by the corresponding α subunit. This chromophore creates spectral overlap with chlorophyll, thus bridging the energetic gap between the phycobiliprotein antenna and the photosystems. We propose that the macromolecular organization of the cryptophyte antenna consists of bulk open and open-braced forms that transfer excitations to photosystems via this bridging closed form phycobiliprotein.
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Affiliation(s)
- Harry W Rathbone
- School of Physics, The University of New South Wales, Sydney, NSW, 2052, Australia
- School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, NSW, 2052, Australia
- UMR144 Cell Biology and Cancer, Institut Curie, Paris, 75005, France
| | - Alistair J Laos
- UNSW RNA Institute and School of Chemistry, The University of New South Wales, Sydney, NSW, 2052, Australia
| | - Katharine A Michie
- School of Physics, The University of New South Wales, Sydney, NSW, 2052, Australia
- School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, NSW, 2052, Australia
- Mark Wainwright Analytical Centre, The University of New South Wales, Sydney, NSW, 2052, Australia
| | - Hasti Iranmanesh
- School of Physics, The University of New South Wales, Sydney, NSW, 2052, Australia
- School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, NSW, 2052, Australia
| | - Joanna Biazik
- Mark Wainwright Analytical Centre, The University of New South Wales, Sydney, NSW, 2052, Australia
| | - Sophia C Goodchild
- School of Molecular Sciences, Macquarie University, Sydney, NSW, 2109, Australia
| | - Pall Thordarson
- UNSW RNA Institute and School of Chemistry, The University of New South Wales, Sydney, NSW, 2052, Australia
| | - Beverley R Green
- Department of Botany, University of British Columbia, Vancouver, BC, Canada
| | - Paul M G Curmi
- School of Physics, The University of New South Wales, Sydney, NSW, 2052, Australia.
- School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, NSW, 2052, Australia.
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Michie KA, Harrop SJ, Rathbone HW, Wilk KE, Teng CY, Hoef‐Emden K, Hiller RG, Green BR, Curmi PMG. Molecular structures reveal the origin of spectral variation in cryptophyte light harvesting antenna proteins. Protein Sci 2023; 32:e4586. [PMID: 36721353 PMCID: PMC9951199 DOI: 10.1002/pro.4586] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2022] [Revised: 01/24/2023] [Accepted: 01/27/2023] [Indexed: 02/02/2023]
Abstract
In addition to their membrane-bound chlorophyll a/c light-harvesting antenna, the cryptophyte algae have evolved a unique phycobiliprotein antenna system located in the thylakoid lumen. The basic unit of this antenna consists of two copies of an αβ protomer where the α and β subunits scaffold different combinations of a limited number of linear tetrapyrrole chromophores. While the β subunit is highly conserved, encoded by a single plastid gene, the nuclear-encoded α subunits have evolved diversified multigene families. It is still unclear how this sequence diversity results in the spectral diversity of the mature proteins. By careful examination of three newly determined crystal structures in comparison with three previously obtained, we show how the α subunit amino acid sequences control chromophore conformations and hence spectral properties even when the chromophores are identical. Previously we have shown that α subunits control the quaternary structure of the mature αβ.αβ complex (either open or closed), however, each species appeared to only harbor a single quaternary form. Here we show that species of the Hemiselmis genus contain expressed α subunit genes that encode both distinct quaternary structures. Finally, we have discovered a common single-copy gene (expressed into protein) consisting of tandem copies of a small α subunit that could potentially scaffold pairs of light harvesting units. Together, our results show how the diversity of the multigene α subunit family produces a range of mature cryptophyte antenna proteins with differing spectral properties, and the potential for minor forms that could contribute to acclimation to varying light regimes.
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Affiliation(s)
- Katharine A. Michie
- School of PhysicsThe University of New South WalesSydneyNew South WalesAustralia
- School of Biotechnology and Biomolecular SciencesThe University of New South WalesSydneyNew South WalesAustralia
- Mark Wainwright Analytical CentreUniversity of New South WalesSydneyNew South WalesAustralia
| | - Stephen J. Harrop
- School of PhysicsThe University of New South WalesSydneyNew South WalesAustralia
- MX Beamlines, Australian SynchrotronClaytonVictoriaAustralia
| | - Harry W. Rathbone
- School of PhysicsThe University of New South WalesSydneyNew South WalesAustralia
- School of Biotechnology and Biomolecular SciencesThe University of New South WalesSydneyNew South WalesAustralia
| | - Krystyna E. Wilk
- School of PhysicsThe University of New South WalesSydneyNew South WalesAustralia
| | - Chang Ying Teng
- Department of BotanyUniversity of British ColumbiaVancouverCanada
| | | | - Roger G. Hiller
- Department of Biological SciencesMacquarie UniversitySydneyNew South WalesAustralia
| | | | - Paul M. G. Curmi
- School of PhysicsThe University of New South WalesSydneyNew South WalesAustralia
- School of Biotechnology and Biomolecular SciencesThe University of New South WalesSydneyNew South WalesAustralia
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Hippmann AA, Schuback N, Moon K, McCrow JP, Allen AE, Foster LF, Green BR, Maldonado MT. Proteomic analysis of metabolic pathways supports chloroplast-mitochondria cross-talk in a Cu-limited diatom. Plant Direct 2022; 6:e376. [PMID: 35079683 PMCID: PMC8777261 DOI: 10.1002/pld3.376] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2021] [Revised: 12/09/2021] [Accepted: 12/11/2021] [Indexed: 05/19/2023]
Abstract
Diatoms are one of the most successful phytoplankton groups in our oceans, being responsible for over 20% of the Earth's photosynthetic productivity. Their chimeric genomes have genes derived from red algae, green algae, bacteria, and heterotrophs, resulting in multiple isoenzymes targeted to different cellular compartments with the potential for differential regulation under nutrient limitation. The resulting interactions between metabolic pathways are not yet fully understood. We previously showed how acclimation to Cu limitation enhanced susceptibility to overreduction of the photosynthetic electron transport chain and its reorganization to favor photoprotection over light harvesting in the oceanic diatom Thalassiosira oceanica (Hippmann et al., 2017, 10.1371/journal.pone.0181753). In order to gain a better understanding of the overall metabolic changes that help alleviate the stress of Cu limitation, we have further analyzed the comprehensive proteomic datasets generated in that study to identify differentially expressed proteins involved in carbon, nitrogen, and oxidative stress-related metabolic pathways. Metabolic pathway analysis showed integrated responses to Cu limitation. The upregulation of ferredoxin (Fdx) was correlated with upregulation of plastidial Fdx-dependent isoenzymes involved in nitrogen assimilation as well as enzymes involved in glutathione synthesis, thus suggesting an integration of nitrogen uptake and metabolism with photosynthesis and oxidative stress resistance. The differential expression of glycolytic isoenzymes located in the chloroplast and mitochondria may enable them to channel both excess electrons and/or ATP between these compartments. An additional support for chloroplast-mitochondrial cross-talk is the increased expression of chloroplast and mitochondrial proteins involved in the proposed malate shunt under Cu limitation.
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Affiliation(s)
- Anna A. Hippmann
- Department of Earth Ocean and Atmospheric ScienceUniversity of British ColumbiaVancouverBritish ColumbiaCanada
| | - Nina Schuback
- Department of Earth Ocean and Atmospheric ScienceUniversity of British ColumbiaVancouverBritish ColumbiaCanada
| | - Kyung‐Mee Moon
- Biochemistry and Molecular BiologyMichael Smith LaboratoriesVancouverBritish ColumbiaCanada
| | - John P. McCrow
- Microbial and Environmental GenomicsJ. Craig Venter InstituteLa JollaCAUSA
| | - Andrew E. Allen
- Microbial and Environmental GenomicsJ. Craig Venter InstituteLa JollaCAUSA
- Scripps Institution of OceanographyUniversity of CaliforniaSan DiegoCAUSA
| | - Leonard F. Foster
- Biochemistry and Molecular BiologyMichael Smith LaboratoriesVancouverBritish ColumbiaCanada
| | - Beverley R. Green
- Department of BotanyUniversity of British ColumbiaVancouverBritish ColumbiaCanada
| | - Maria T. Maldonado
- Department of Earth Ocean and Atmospheric ScienceUniversity of British ColumbiaVancouverBritish ColumbiaCanada
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Rathbone HW, Michie KA, Landsberg MJ, Green BR, Curmi PMG. Scaffolding proteins guide the evolution of algal light harvesting antennas. Nat Commun 2021; 12:1890. [PMID: 33767155 PMCID: PMC7994580 DOI: 10.1038/s41467-021-22128-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2020] [Accepted: 02/17/2021] [Indexed: 11/19/2022] Open
Abstract
Photosynthetic organisms have developed diverse antennas composed of chromophorylated proteins to increase photon capture. Cryptophyte algae acquired their photosynthetic organelles (plastids) from a red alga by secondary endosymbiosis. Cryptophytes lost the primary red algal antenna, the red algal phycobilisome, replacing it with a unique antenna composed of αβ protomers, where the β subunit originates from the red algal phycobilisome. The origin of the cryptophyte antenna, particularly the unique α subunit, is unknown. Here we show that the cryptophyte antenna evolved from a complex between a red algal scaffolding protein and phycoerythrin β. Published cryo-EM maps for two red algal phycobilisomes contain clusters of unmodelled density homologous to the cryptophyte-αβ protomer. We modelled these densities, identifying a new family of scaffolding proteins related to red algal phycobilisome linker proteins that possess multiple copies of a cryptophyte-α-like domain. These domains bind to, and stabilise, a conserved hydrophobic surface on phycoerythrin β, which is the same binding site for its primary partner in the red algal phycobilisome, phycoerythrin α. We propose that after endosymbiosis these scaffolding proteins outcompeted the primary binding partner of phycoerythrin β, resulting in the demise of the red algal phycobilisome and emergence of the cryptophyte antenna. Cryptophytes acquired plastids from red algae but replaced the light-harvesting phycobilisome with a unique cryptophyte antenna. Here via analysis of phycobilisome cryo-EM structures, Rathbone et al. propose that the α subunit of the cryptophyte antenna originated from phycobilisome linker proteins
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Affiliation(s)
- Harry W Rathbone
- School of Physics, University of New South Wales, Sydney, NSW, 2052, Australia
| | - Katharine A Michie
- School of Physics, University of New South Wales, Sydney, NSW, 2052, Australia.,Mark Wainwright Analytical Centre, University of New South Wales, Sydney, NSW, 2052, Australia
| | - Michael J Landsberg
- School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, QLD, Australia
| | - Beverley R Green
- Botany Department, University of British Columbia, Vancouver, BC, V6N 3T7, Canada
| | - Paul M G Curmi
- School of Physics, University of New South Wales, Sydney, NSW, 2052, Australia.
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Abstract
The phycobilisome (PBS) is the major light-harvesting complex of photosynthesis in cyanobacteria, red algae, and glaucophyte algae. In spite of the fact that it is very well structured to absorb light and transfer it efficiently to photosynthetic reaction centers, it has been completely lost in the green algae and plants. It is difficult to see how selection alone could account for such a major loss. An alternative scenario takes into account the role of chance, enabled by (contingent on) the evolution of an alternative antenna system early in the diversification of the three lineages from the first photosynthetic eukaryote.
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Affiliation(s)
- Beverley R Green
- Botany Department, University of British Columbia, Vancouver, BC V6N 3T7, Canada
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Kieselbach T, Cheregi O, Green BR, Funk C. Proteomic analysis of the phycobiliprotein antenna of the cryptophyte alga Guillardia theta cultured under different light intensities. Photosynth Res 2018; 135:149-163. [PMID: 28540588 PMCID: PMC5784005 DOI: 10.1007/s11120-017-0400-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2017] [Accepted: 05/16/2017] [Indexed: 06/01/2023]
Abstract
Plants and algae have developed various light-harvesting mechanisms for optimal delivery of excitation energy to the photosystems. Cryptophyte algae have evolved a novel soluble light-harvesting antenna utilizing phycobilin pigments to complement the membrane-intrinsic Chl a/c-binding LHC antenna. This new antenna consists of the plastid-encoded β-subunit, a relic of the ancestral phycobilisome, and a novel nuclear-encoded α-subunit unique to cryptophytes. Together, these proteins form the active α1β·α2β-tetramer. In all cryptophyte algae investigated so far, the α-subunits have duplicated and diversified into a large gene family. Although there is transcriptional evidence for expression of all these genes, the X-ray structures determined to date suggest that only two of the α-subunit genes might be significantly expressed at the protein level. Using proteomics, we show that in phycoerythrin 545 (PE545) of Guillardia theta, the only cryptophyte with a sequenced genome, all 20 α-subunits are expressed when the algae grow under white light. The expression level of each protein depends on the intensity of the growth light, but there is no evidence for a specific light-dependent regulation of individual members of the α-subunit family under the growth conditions applied. GtcpeA10 seems to be a special member of the α-subunit family, because it consists of two similar N- and C-terminal domains, which likely are the result of a partial tandem gene duplication. The proteomics data of this study have been deposited to the ProteomeXchange Consortium and have the dataset identifiers PXD006301 and 10.6019/PXD006301.
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Affiliation(s)
| | - Otilia Cheregi
- Department of Chemistry, Umeå University, 90187 Umeå, Sweden
| | - Beverley R. Green
- Botany Department, University of British Columbia, Vancouver, BC V6T 1Z4 Canada
| | - Christiane Funk
- Department of Chemistry, Umeå University, 90187 Umeå, Sweden
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7
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Hippmann AA, Schuback N, Moon KM, McCrow JP, Allen AE, Foster LJ, Green BR, Maldonado MT. Contrasting effects of copper limitation on the photosynthetic apparatus in two strains of the open ocean diatom Thalassiosira oceanica. PLoS One 2017; 12:e0181753. [PMID: 28837661 PMCID: PMC5570362 DOI: 10.1371/journal.pone.0181753] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2017] [Accepted: 07/06/2017] [Indexed: 11/25/2022] Open
Abstract
There is an intricate interaction between iron (Fe) and copper (Cu) physiology in diatoms. However, strategies to cope with low Cu are largely unknown. This study unveils the comprehensive restructuring of the photosynthetic apparatus in the diatom Thalassiosira oceanica (CCMP1003) in response to low Cu, at the physiological and proteomic level. The restructuring results in a shift from light harvesting for photochemistry—and ultimately for carbon fixation—to photoprotection, reducing carbon fixation and oxygen evolution. The observed decreases in the physiological parameters Fv/Fm, carbon fixation, and oxygen evolution, concomitant with increases in the antennae absorption cross section (σPSII), non-photochemical quenching (NPQ) and the conversion factor (φe:C/ηPSII) are in agreement with well documented cellular responses to low Fe. However, the underlying proteomic changes due to low Cu are very different from those elicited by low Fe. Low Cu induces a significant four-fold reduction in the Cu-containing photosynthetic electron carrier plastocyanin. The decrease in plastocyanin causes a bottleneck within the photosynthetic electron transport chain (ETC), ultimately leading to substantial stoichiometric changes. Namely, 2-fold reduction in both cytochrome b6f complex (cytb6f) and photosystem II (PSII), no change in the Fe-rich PSI and a 40- and 2-fold increase in proteins potentially involved in detoxification of reactive oxygen species (ferredoxin and ferredoxin:NADP+ reductase, respectively). Furthermore, we identify 48 light harvesting complex (LHC) proteins in the publicly available genome of T. oceanica and provide proteomic evidence for 33 of these. The change in the LHC composition within the antennae in response to low Cu underlines the shift from photochemistry to photoprotection in T. oceanica (CCMP1003). Interestingly, we also reveal very significant intra-specific strain differences. Another strain of T. oceanica (CCMP 1005) requires significantly higher Cu concentrations to sustain both its maximal and minimal growth rate compared to CCMP 1003. Under low Cu, CCMP 1005 decreases its growth rate, cell size, Chla and total protein per cell. We argue that the reduction in protein per cell is the main strategy to decrease its cellular Cu requirement, as none of the other parameters tested are affected. Differences between the two strains, as well as differences between the well documented responses to low Fe and those presented here in response to low Cu are discussed.
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Affiliation(s)
- Anna A. Hippmann
- Department of Earth, Ocean, and Atmospheric Sciences, University of British Columbia, Vancouver, British Columbia, Canada
- * E-mail: (AAH); (MTM)
| | - Nina Schuback
- Department of Earth, Ocean, and Atmospheric Sciences, University of British Columbia, Vancouver, British Columbia, Canada
| | - Kyung-Mee Moon
- Department of Biochemistry & Molecular Biology, University of British Columbia, Vancouver, British Columbia, Canada
| | - John P. McCrow
- Department of Microbial & Environmental Genomics, J. Craig Venter Institute, La Jolla, California, United States of America
| | - Andrew E. Allen
- Department of Microbial & Environmental Genomics, J. Craig Venter Institute, La Jolla, California, United States of America
| | - Leonard J. Foster
- Department of Biochemistry & Molecular Biology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Beverley R. Green
- Department of Botany, University of British Columbia, Vancouver, British Columbia, Canada
| | - Maria T. Maldonado
- Department of Earth, Ocean, and Atmospheric Sciences, University of British Columbia, Vancouver, British Columbia, Canada
- * E-mail: (AAH); (MTM)
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Abstract
The venoms of cone snails provide a rich source of neuroactive peptides (conotoxins). Several venom peptide families have been identified that are either agonists (ι- and δ-conotoxins) or antagonists (μ- and μO-conotoxins) of voltage-gated sodium channels (VGSCs). Members of these conotoxin classes have been integral in identifying and characterizing specific neurotoxin binding sites on the channel. Furthermore, given the specificity of some of these peptides for one sodium channel subtype over another, conotoxins have also proven useful in exploring differences between VGSC subtypes. This chapter summarizes the current knowledge of the structure and function based on the results of conotoxin interactions with VGSCs and correlates the peptides with the phylogeny of the Conus species from which they were derived.
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Affiliation(s)
- B R Green
- University of Utah, Salt Lake City, UT, United States; Monash University, Parkville, VIC, Australia
| | - B M Olivera
- University of Utah, Salt Lake City, UT, United States
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Arpin PC, Turner DB, McClure SD, Jumper CC, Mirkovic T, Challa JR, Lee J, Teng CY, Green BR, Wilk KE, Curmi PMG, Hoef-Emden K, McCamant DW, Scholes GD. Spectroscopic Studies of Cryptophyte Light Harvesting Proteins: Vibrations and Coherent Oscillations. J Phys Chem B 2015; 119:10025-34. [DOI: 10.1021/acs.jpcb.5b04704] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Paul C. Arpin
- Department
of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada
| | - Daniel B. Turner
- Department
of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada
| | - Scott D. McClure
- Department
of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada
| | - Chanelle C. Jumper
- Department
of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada
| | - Tihana Mirkovic
- Department
of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada
| | - J. Reddy Challa
- Department
of Chemistry, University of Rochester, Rochester, New York 14627, United States
| | - Joohyun Lee
- Department
of Chemistry, University of Rochester, Rochester, New York 14627, United States
| | - Chang Ying Teng
- Department
of Botany, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
| | - Beverley R. Green
- Department
of Botany, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
| | - Krystyna E. Wilk
- School
of Physics, The University of New South Wales, Sydney, New South Wales 2052, Australia
| | - Paul M. G. Curmi
- School
of Physics, The University of New South Wales, Sydney, New South Wales 2052, Australia
| | - Kerstin Hoef-Emden
- Botanical
Institute, Cologne Biocenter, University of Cologne, 50674 Cologne, Germany
| | - David W. McCamant
- Department
of Chemistry, University of Rochester, Rochester, New York 14627, United States
| | - Gregory D. Scholes
- Department
of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada
- Department
of Chemistry, Princeton University, Washington Road, Princeton, New Jersey 08544, United States
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Guo J, Green BR, Maldonado MT. Sequence Analysis and Gene Expression of Potential Components of Copper Transport and Homeostasis in Thalassiosira pseudonana. Protist 2015; 166:58-77. [DOI: 10.1016/j.protis.2014.11.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2014] [Revised: 11/03/2014] [Accepted: 11/29/2014] [Indexed: 10/24/2022]
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Affiliation(s)
| | - B R Green
- Mintek, Private Bag X3015, Randburg, 2125, South Africa
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12
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Huesgen PF, Alami M, Lange PF, Foster LJ, Schröder WP, Overall CM, Green BR. Proteomic amino-termini profiling reveals targeting information for protein import into complex plastids. PLoS One 2013; 8:e74483. [PMID: 24066144 PMCID: PMC3774753 DOI: 10.1371/journal.pone.0074483] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2013] [Accepted: 08/01/2013] [Indexed: 01/14/2023] Open
Abstract
In organisms with complex plastids acquired by secondary endosymbiosis from a photosynthetic eukaryote, the majority of plastid proteins are nuclear-encoded, translated on cytoplasmic ribosomes, and guided across four membranes by a bipartite targeting sequence. In-depth understanding of this vital import process has been impeded by a lack of information about the transit peptide part of this sequence, which mediates transport across the inner three membranes. We determined the mature N-termini of hundreds of proteins from the model diatom Thalassiosira pseudonana, revealing extensive N-terminal modification by acetylation and proteolytic processing in both cytosol and plastid. We identified 63 mature N-termini of nucleus-encoded plastid proteins, deduced their complete transit peptide sequences, determined a consensus motif for their cleavage by the stromal processing peptidase, and found evidence for subsequent processing by a plastid methionine aminopeptidase. The cleavage motif differs from that of higher plants, but is shared with other eukaryotes with complex plastids.
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Affiliation(s)
- Pitter F. Huesgen
- Centre for Blood Research and Department of Oral Biological and Medical Sciences, University of British Columbia, Vancouver, British Columbia, Canada
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Meriem Alami
- Department of Botany, University of British Columbia, Vancouver, British Columbia, Canada
| | - Philipp F. Lange
- Centre for Blood Research and Department of Oral Biological and Medical Sciences, University of British Columbia, Vancouver, British Columbia, Canada
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Leonard J. Foster
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia, Canada
- Centre for High-Throughput Biology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Wolfgang P. Schröder
- Centre for Blood Research and Department of Oral Biological and Medical Sciences, University of British Columbia, Vancouver, British Columbia, Canada
- Department of Chemistry and Umeå Plant Science Centre, Umeå University, Umeå, Sweden
| | - Christopher M. Overall
- Centre for Blood Research and Department of Oral Biological and Medical Sciences, University of British Columbia, Vancouver, British Columbia, Canada
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Beverley R. Green
- Department of Botany, University of British Columbia, Vancouver, British Columbia, Canada
- * E-mail:
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Teng CY, Dang Y, Danne JC, Waller RF, Green BR. Mitochondrial Genes of Dinoflagellates Are Transcribed by a Nuclear-Encoded Single-Subunit RNA Polymerase. PLoS One 2013; 8:e65387. [PMID: 23840326 PMCID: PMC3686807 DOI: 10.1371/journal.pone.0065387] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2013] [Accepted: 04/27/2013] [Indexed: 11/18/2022] Open
Abstract
Dinoflagellates are a large group of algae that contribute significantly to marine productivity and are essential photosynthetic symbionts of corals. Although these algae have fully-functioning mitochondria and chloroplasts, both their organelle genomes have been highly reduced and the genes fragmented and rearranged, with many aberrant transcripts. However, nothing is known about their RNA polymerases. We cloned and sequenced the gene for the nuclear-encoded mitochondrial polymerase (RpoTm) of the dinoflagellate Heterocapsa triquetra and showed that the protein presequence targeted a GFP construct into yeast mitochondria. The gene belongs to a small gene family, which includes a variety of 3′-truncated copies that may have originated by retroposition. The catalytic C-terminal domain of the protein shares nine conserved sequence blocks with other single-subunit polymerases and is predicted to have the same fold as the human enzyme. However, the N-terminal (promoter binding/transcription initiation) domain is not well-conserved. In conjunction with the degenerate nature of the mitochondrial genome, this suggests a requirement for novel accessory factors to ensure the accurate production of functional mRNAs.
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Affiliation(s)
- Chang Ying Teng
- Botany Department, University of British Columbia, Vancouver, B.C., Canada
- Life Sciences Department, Ludong University, Yantai, Shandong, China
| | - Yunkun Dang
- Botany Department, University of British Columbia, Vancouver, B.C., Canada
| | - Jillian C. Danne
- School of Botany, University of Melbourne, Melbourne, Victoria, Australia
| | - Ross F. Waller
- School of Botany, University of Melbourne, Melbourne, Victoria, Australia
| | - Beverley R. Green
- Botany Department, University of British Columbia, Vancouver, B.C., Canada
- * E-mail:
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Wu H, Roy S, Alami M, Green BR, Campbell DA. Photosystem II photoinactivation, repair, and protection in marine centric diatoms. Plant Physiol 2012; 160:464-76. [PMID: 22829321 PMCID: PMC3440219 DOI: 10.1104/pp.112.203067] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2012] [Accepted: 07/23/2012] [Indexed: 05/02/2023]
Abstract
Diatoms are important contributors to aquatic primary production, and can dominate phytoplankton communities under variable light regimes. We grew two marine diatoms, the small Thalassiosira pseudonana and the large Coscinodiscus radiatus, across a range of temperatures and treated them with a light challenge to understand their exploitation of variable light environments. In the smaller T. pseudonana, photosystem II (PSII) photoinactivation outran the clearance of PSII protein subunits, particularly in cells grown at sub- or supraoptimal temperatures. In turn the absorption cross section serving PSII photochemistry was down-regulated in T. pseudonana through induction of a sustained phase of nonphotochemical quenching that relaxed only slowly over 30 min of subsequent low-light incubation. In contrast, in the larger diatom C. radiatus, PSII subunit turnover was sufficient to counteract a lower intrinsic susceptibility to photoinactivation, and C. radiatus thus did not need to induce sustained nonphotochemical quenching under the high-light treatment. T. pseudonana thus incurs an opportunity cost of sustained photosynthetic down-regulation after the end of an upward light shift, whereas the larger C. radiatus can maintain a balanced PSII repair cycle under comparable conditions.
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Affiliation(s)
- Hongyan Wu
- Biology, Mount Allison University, Sackville, New Brunswick, Canada E4L 1G7 (H.W., D.A.C.); College of Biological Engineering, Hubei University of Technology, Wuhan, Hubei 430068, China (H.W.); Institut des sciences de la mer de Rimouski, Université du Québec, Rimouski, Quebec, Canada G5L 3A1 (S.R.); and Botany, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4 (M.A., B.R.G.)
| | - Suzanne Roy
- Biology, Mount Allison University, Sackville, New Brunswick, Canada E4L 1G7 (H.W., D.A.C.); College of Biological Engineering, Hubei University of Technology, Wuhan, Hubei 430068, China (H.W.); Institut des sciences de la mer de Rimouski, Université du Québec, Rimouski, Quebec, Canada G5L 3A1 (S.R.); and Botany, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4 (M.A., B.R.G.)
| | - Meriem Alami
- Biology, Mount Allison University, Sackville, New Brunswick, Canada E4L 1G7 (H.W., D.A.C.); College of Biological Engineering, Hubei University of Technology, Wuhan, Hubei 430068, China (H.W.); Institut des sciences de la mer de Rimouski, Université du Québec, Rimouski, Quebec, Canada G5L 3A1 (S.R.); and Botany, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4 (M.A., B.R.G.)
| | - Beverley R. Green
- Biology, Mount Allison University, Sackville, New Brunswick, Canada E4L 1G7 (H.W., D.A.C.); College of Biological Engineering, Hubei University of Technology, Wuhan, Hubei 430068, China (H.W.); Institut des sciences de la mer de Rimouski, Université du Québec, Rimouski, Quebec, Canada G5L 3A1 (S.R.); and Botany, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4 (M.A., B.R.G.)
| | - Douglas A. Campbell
- Biology, Mount Allison University, Sackville, New Brunswick, Canada E4L 1G7 (H.W., D.A.C.); College of Biological Engineering, Hubei University of Technology, Wuhan, Hubei 430068, China (H.W.); Institut des sciences de la mer de Rimouski, Université du Québec, Rimouski, Quebec, Canada G5L 3A1 (S.R.); and Botany, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4 (M.A., B.R.G.)
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15
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Green BR, Reddy A, Jha M. Mesenteric fat necrosis after recent surgery causing bowel obstruction: a case report and review of the literature. J Postgrad Med 2012; 58:54-6. [PMID: 22387649 DOI: 10.4103/0022-3859.93253] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
Mesenteric fat necrosis causing bowel obstruction is a rare occurrence with only one case reported in humans. It is due to accidental or surgical trauma to the adipose tissue with extracellular liberation of fat or enzymatic lysis of fat due to the release of lipases resulting in fibrosis. Preoperative imaging may often be misleading and fail to identify fat necrosis as the cause of bowel obstruction. As surgical intervention is the only suitable treatment option in cases of failed conservative treatment, the diagnosis is made postoperatively. There is no published advice on the management of mesenteric fat necrosis. We recommend safe operating techniques to minimize the risk of developing fat necrosis and its potential harmful consequences.
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Affiliation(s)
- B R Green
- Department of Surgery, James Cook University Hospital, Marton Road, Middlesbrough, TS4 3BW, United Kingdom.
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16
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Funk C, Alami M, Tibiletti T, Green BR. High light stress and the one-helix LHC-like proteins of the cryptophyte Guillardia theta. Biochim Biophys Acta 2011; 1807:841-6. [PMID: 21459077 DOI: 10.1016/j.bbabio.2011.03.011] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2011] [Revised: 03/23/2011] [Accepted: 03/24/2011] [Indexed: 10/18/2022]
Abstract
Cryptophytes like the cryptomonad Guillardia theta are part of the marine phytoplankton and therefore major players in global carbon and biogeochemical cycles. Despite the importance for the cell in being able to cope with large changes in illumination on a daily basis, very little is known about photoprotection mechanisms in cryptophytes. Here, we show that Guillardia theta is able to perform non-photochemical quenching, although none of the usual xanthophyll cycle pigments (e.g., zeaxanthin, diadinoxanthin, diatoxanthin) are present at detectable levels. Instead, acclimation to high light intensity seems to involve an increase of alloxanthin. Guillardia theta has genes for 2 one-helix "light-harvesting-like" proteins, related to some cyanobacterial genes which are induced in response to high light stress. Both the plastid-encoded gene (hlipP) and the nucleomorph-encoded gene (HlipNm) are expressed, but transcript levels decrease rather than increase during high light exposure, suggesting that they are not involved in a high light stress response. The HlipNm protein was detected with a specific antibody; expression was constant, independent of the light exposure.
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Affiliation(s)
- Christiane Funk
- Department of Chemistry, Umeå University, S-90187 Umeå, Sweden.
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17
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Abstract
Chloroplast genomes have retained a core set of genes from their cyanobacterial ancestor, most of them required for the light reactions of photosynthesis or functions connected with transcription and translation. Other genes have been transferred to the nucleus or were lost in a lineage-specific manner. The genomes are distinguished by the selection of genes retained, whether or not transcripts are edited, presence/absence of introns and small repeats and their physical organization. Plants and green algae have kept fewer plastid genes than either the red algae or the chromistan algae, which obtained their plastids from red algae by secondary endosymbiosis. Photosynthetic dinoflagellates have the fewest (fewer than 20), but still grow photoautotrophically. All chloroplast genomes map as a circle, but there have been extensive rearrangements of gene order even between related species. Genome sizes vary much more than gene content, depending on the extent of gene duplication and small repeats and the size of intergenic spacers.
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Affiliation(s)
- Beverley R Green
- Botany Department, University of British Columbia, #3529-6270 University Blvd., Vancouver, BC V6T 1Z4, Canada.
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18
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Oudot-Le Secq MP, Green BR. Complex repeat structures and novel features in the mitochondrial genomes of the diatoms Phaeodactylum tricornutum and Thalassiosira pseudonana. Gene 2011; 476:20-6. [PMID: 21320580 DOI: 10.1016/j.gene.2011.02.001] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2010] [Revised: 12/12/2010] [Accepted: 02/02/2011] [Indexed: 11/18/2022]
Abstract
The mitochondrial genome of the raphid pennate diatom Phaeodactylum tricornutum has several novel features compared with the mitochondrial genomes of the centric diatom Thalassiosira pseudonana and the araphid pennate diatom Synedra acus. It is almost double the size (77,356 bp) due to a 35,454 bp sequence block consisting of an elaborate combination of direct repeats, making it the largest stramenopile (heterokont) mitochondrial genome known. In addition, the cox1 gene has a +1 translational frameshift involving Pro codons CCC and CCT, the first translational frameshift to be detected in an algal mitochondrial genome. The nad9 and rps14 genes are fused by the insertion of an in-frame sequence and cotranscribed. The nad11 gene is split into two parts corresponding to the FeS and molybdate-binding domains, but both parts are still on the mitochondrial genome, in contrast to the brown algae where the second domain appears to have been transferred to the nucleus. In contrast to P. tricornutum, the repeat region of T. pseudonana consists of a much smaller 4790 bp string of almost identical double-hairpin elements, evidence of slipped-strand mispairing and active gene conversion. The diatom mitochondrial genomes have undergone considerable gene rearrangement since the three lineages of diatoms diverged, but all three have kept their repeat regions segregated from their relatively compact coding regions.
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Affiliation(s)
- Marie-Pierre Oudot-Le Secq
- Botany Department, University of British Columbia, 6270 University Boulevard, Vancouver, British Columbia, Canada V6T 1Z4.
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19
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Green BR. After the primary endosymbiosis: an update on the chromalveolate hypothesis and the origins of algae with Chl c. Photosynth Res 2011; 107:103-15. [PMID: 20676772 DOI: 10.1007/s11120-010-9584-2] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2010] [Accepted: 07/07/2010] [Indexed: 05/24/2023]
Abstract
The chromalveolate hypothesis proposed by Cavalier-Smith (J Euk Microbiol 46:347-366, 1999) suggested that all the algae with chlorophyll c (heterokonts, haptophytes, cryptophytes, and dinoflagellates), as well as the ciliates, apicomplexans, oomycetes, and other non-photosynthetic relatives, shared a common ancestor that acquired a chloroplast by secondary endosymbiosis of a red alga. Much of the evidence from plastid and nuclear genomes supports a red algal origin for plastids of the photosynthetic lineages, but the number of secondary endosymbioses and the number of plastid losses have not been resolved. The issue is complicated by the fact that nuclear genomes are mosaics of genes acquired over a very long time period, not only by vertical descent but also by endosymbiotic and horizontal gene transfer. Phylogenomic analysis of the available whole-genome data has suggested major alterations to our view of eukaryotic evolution, and given rise to alternative models. The next few years may see even more changes once a more representative collection of sequenced genomes becomes available.
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Affiliation(s)
- Beverley R Green
- Botany Department, University of British Columbia, Vancouver, B.C, V6T 1Z4, Canada.
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20
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Zhu SH, Green BR. Photoprotection in the diatom Thalassiosira pseudonana: Role of LI818-like proteins in response to high light stress. Biochimica et Biophysica Acta (BBA) - Bioenergetics 2010; 1797:1449-57. [DOI: 10.1016/j.bbabio.2010.04.003] [Citation(s) in RCA: 127] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2009] [Revised: 03/11/2010] [Accepted: 04/05/2010] [Indexed: 10/19/2022]
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21
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Abstract
The chloroplast genome of a dinoflagellate consists of a group of small circular DNA molecules (minicircles), most of which carry a single gene. With RT-PCR, primer extension, and Northern analyses, we show that the entire minicircle is transcribed and that some minicircles can produce RNAs larger than themselves. Using an RNA ligase-mediated rapid amplification of cDNA ends method, we were able to detect large processed precursors that are generated by endonucleolytic cleavage of an even longer molecule. This cleavage produces the mature mRNA 3'-end and at the same time the 5'-end of the precursor. The tRNAs encoded by the petD and psbE minicircles appear to be processed in the same way. We propose a "rolling circle" model for chloroplast transcription in which transcription would proceed continuously around the minicircular DNA to produce transcripts larger than the minicircle itself. These transcripts would be further processed into discrete mature mRNAs and tRNAs.
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Affiliation(s)
- Yunkun Dang
- Botany Department, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
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22
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Dang Y, Green BR. Substitutional editing of Heterocapsa triquetra chloroplast transcripts and a folding model for its divergent chloroplast 16S rRNA. Gene 2009; 442:73-80. [PMID: 19376212 DOI: 10.1016/j.gene.2009.04.006] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2008] [Revised: 03/19/2009] [Accepted: 04/06/2009] [Indexed: 11/18/2022]
Abstract
Substitutional editing increases genomic plasticity by changing or modifying bases at the RNA level. In this study we sequenced 10 mature chloroplast mRNAs, the chloroplast 16S rRNA and a partial chloroplast 23S rRNA from the dinoflagellate Heterocapsa triquetra, and found multiple types of substitutional editing, with A-to-G editing predominating. A-to-G editing of mRNAs converts two unusual AUA start codons into conventional AUG start codons, but three AUA start codons are not edited, showing that this dinoflagellate chloroplast has three possible start codons: AUG, AUA and UUG. To analyze the editing effects on rRNAs, we computationally predicted the secondary structure of the 16S rRNA based on the E. coli model. There are twenty editing sites in well-conserved regions of the secondary structure and eleven out of them restore conservation with other models. Moreover, A-to-G editing sites are frequently found in loop regions rather than double-stranded regions, suggesting that the A-to-G editing mechanism in dinoflagellate chloroplasts is different from that responsible for animal nuclear A-to-I(G) editing. The model of the edited 16S rRNA derived by the comparative method shares conserved secondary structural elements with other 16S rRNAs in spite of its very divergent primary sequence, supporting its role as a functional component of the chloroplast ribosome.
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Affiliation(s)
- Yunkun Dang
- Botany Department, University of British Columbia, Vancouver, B.C., Canada.
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23
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Samuel MA, Chaal BK, Lampard G, Green BR, Ellis BE. Surviving the passage: Non-canonical stromal targeting of an Arabidopsis mitogen-activated protein kinase kinase. Plant Signal Behav 2008; 3:6-12. [PMID: 19516975 PMCID: PMC2633948 DOI: 10.4161/psb.3.1.4856] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2007] [Accepted: 08/13/2007] [Indexed: 05/14/2023]
Abstract
In plants, mitogen-activated protein kinases (MAPK) have been implicated in signalling associated with many processes, including cellular differentiation, organ development, cell death and stress/hormone signalling. While MAPK cascades are known to act in the cytosol and the nucleus, sequence analysis of the Arabidopsis MAPK cascade proteins predicts the presence of import signals that would target some of them to other organelles. In vitro uptake experiments confirm the predicted import of an oxidant-responsive MAPKK, AtMKK4, into the chloroplast. Unexpectedly, the imported MKK4 protein was not processed through stromal peptidase-dependent cleavage of the N-terminal signal peptide, thus leaving the pre-protein intact. Nevertheless, the N-terminal region was shown to be essential both for the import process and for the ability of MKK4 to activate its cognate MAPK targets in vivo. MKK4 import also occurred irrespective of the activation status of the kinase. The import of this primarily cytosolic oxidant-stimulated AtMKK4 into the chloroplasts, organelles with high redox fluxes, suggests that one of the functions of MKK4 might be to help coordinate intercompartment responses to cellular redox imbalances.
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Affiliation(s)
- Marcus A Samuel
- Michael Smith Laboratories; University of British Columbia; Vancouver Canada
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24
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Nelson MJ, Dang Y, Filek E, Zhang Z, Yu VWC, Ishida KI, Green BR. Identification and transcription of transfer RNA genes in dinoflagellate plastid minicircles. Gene 2007; 392:291-8. [PMID: 17350182 DOI: 10.1016/j.gene.2007.01.018] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2006] [Revised: 12/14/2006] [Accepted: 01/23/2007] [Indexed: 11/25/2022]
Abstract
The dinoflagellate chloroplast genome is unique in that the genes are found on small circular DNA molecules carrying from one to three genes. In addition, only 14 of the typical chloroplast-located genes have so far been discovered on minicircles, while a number have been transferred to the nucleus. We have sequenced four new minicircles from the dinoflagellate Heterocapsa triquetra, three of which carry a single protein-coding gene (psbD, psbE, petD) and one that appears to be an "empty" circle. Using the tRNA prediction programs ARAGORN and tRNAscan-SE, tRNA-Met was found in the petD circle immediately downstream of the end of petD, while tRNA-Trp and tRNA-Pro were detected in the psbE and petD circles as well as in several chimeric circles of H. triquetra and the psbA minicircles of Heterocapsa pygmaea. RT-PCR showed that the tRNAs were co-transcribed with the protein-coding genes that preceded them, and cleaved from the precursor before a poly(U) tail was added to the mRNA.
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Affiliation(s)
- Martha J Nelson
- Botany Department, University of British Columbia, #3529-6270 University Blvd., Vancouver, B.C., Canada V6T 1Z4
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25
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Oudot-Le Secq MP, Grimwood J, Shapiro H, Armbrust EV, Bowler C, Green BR. Chloroplast genomes of the diatoms Phaeodactylum tricornutum and Thalassiosira pseudonana: comparison with other plastid genomes of the red lineage. Mol Genet Genomics 2007; 277:427-39. [PMID: 17252281 DOI: 10.1007/s00438-006-0199-4] [Citation(s) in RCA: 127] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2006] [Accepted: 11/30/2006] [Indexed: 11/28/2022]
Abstract
The chloroplast genomes of the pennate diatom Phaeodactylum tricornutum and the centric diatom Thalassiosira pseudonana have been completely sequenced and are compared with those of other secondary plastids of the red lineage: the centric diatom Odontella sinensis, the haptophyte Emiliania huxleyi, and the cryptophyte Guillardia theta. All five chromist genomes are compact, with small intergenic regions and no introns. The three diatom genomes are similar in gene content with 127-130 protein-coding genes, and genes for 27 tRNAs, three ribosomal RNAs and two small RNAs (tmRNA and signal recognition particle RNA). All three genomes have open-reading frames corresponding to ORFs148, 355 and 380 of O. sinensis, which have been assigned the names ycf88, ycf89 and ycf90. Gene order is not strictly conserved, but there are a number of conserved gene clusters showing remnants of red algal origin. The acpP, tsf and psb28 genes appear to be on the way from the plastid to the host nucleus, indicating that endosymbiotic gene transfer is a continuing process.
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26
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Chaal BK, Green BR. Protein targeting in "secondary" or "complex" chloroplasts. Methods Mol Biol 2007; 390:207-17. [PMID: 17951690 DOI: 10.1007/978-1-59745-466-7_14] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2023]
Abstract
All the algae with chlorophyll (Chl) c (haptophytes, cryptophytes, and heterokonts such as diatoms) acquired their chloroplasts by secondary endosymbiosis, where a nonphotosynthetic eukaryote host engulfed (or was invaded by) a red alga. This resulted in chloroplasts with four bounding membranes. The outermost membrane (chloroplast endoplasmic reticulum [ER]), is physically continuous with the rough ER, and in some algal species can be seen to have cytoplasmic ribosomes attached to its outer surface. All nuclear-encoded chloroplast proteins have an N-terminal ER targeting sequence, which is cleaved off during transit across this membrane. We know little about how proteins cross the next membrane and engage the import translocons of the envelope membranes. One way to study the targeting of proteins across the inner membranes is to make constructs lacking the ER signal sequence, translate them in vitro, and assay their import into pea chloroplasts.
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Affiliation(s)
- Balbir K Chaal
- Botany Department, University of British Columbia, Vancouver, Canada
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27
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Nelson MJ, Green BR. Double hairpin elements and tandem repeats in the non-coding region of Adenoides eludens chloroplast gene minicircles. Gene 2005; 358:102-10. [PMID: 16043313 DOI: 10.1016/j.gene.2005.05.024] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2004] [Revised: 05/03/2005] [Accepted: 05/17/2005] [Indexed: 10/25/2022]
Abstract
Dinoflagellate plastid genomes are unique in having a reduced number of genes, most of which are found on unigenic minicircles of 2-3 kb. Although the dinoflagellate Adenoides eludens has larger minicircles of about 5 kb, they still carry only one gene. In addition, digenic circles of about 10 kb were detected and mapped by PCR. The non-coding regions of both unigenic and digenic circles share a number of common features including a pair of conserved cores in opposite orientation, four large families of tandem repeats and a number of double hairpin elements (DHEs). They most closely resemble the non-coding regions of the Symbiodinium psbA minicircles, but are much longer, less conserved and have an even greater variety of DHEs and tandem repeats. The presence of so many recombinogenic elements suggests models for the origin of minicircles from a multigenic ancestral chloroplast genome, and raises the possibility of recombination-directed replication rather than defined replication origins in the minicircles.
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Affiliation(s)
- Martha J Nelson
- Botany Department, University of British Columbia, #3529-6270 University Blvd., Vancouver, B.C. Canada
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28
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Abstract
Heme biosynthesis represents one of the most essential metabolic pathways in living organisms, providing the precursors for cytochrome prosthetic groups, photosynthetic pigments, and vitamin B(12). Using genomic data, we have compared the heme pathway in the diatom Thalassiosira pseudonana and the red alga Cyanidioschyzon merolae to those of green algae and higher plants, as well as to those of heterotrophic eukaryotes (fungi, apicomplexans, and animals). Phylogenetic analyses showed the mosaic character of this pathway in photosynthetic eukaryotes. Although most of the algal and plant enzymes showed the expected plastid (cyanobacterial) origin, at least one of them (porphobilinogen deaminase) appears to have a mitochondrial (alpha-proteobacterial) origin. Another enzyme, glutamyl-tRNA synthase, obviously originated in the eukaryotic nucleus. Because all the plastid-targeted sequences consistently form a well-supported cluster, this suggests that genes were either transferred from the primary endosymbiont (cyanobacteria) to the primary host nucleus shortly after the primary endosymbiotic event or replaced with genes from other sources at an equally early time, i.e., before the formation of three primary plastid lineages. The one striking exception to this pattern is ferrochelatase, the enzyme catalyzing the first committed step to heme and bilin pigments. In this case, two red algal sequences do not cluster either with the other plastid sequences or with cyanobacterial sequences and appear to have a proteobacterial origin like that of the apicomplexan parasites Plasmodium and Toxoplasma. Although the heterokonts also acquired their plastid via secondary endosymbiosis from a red alga, the diatom has a typical plastid-cyanobacterial ferrochelatase. We have not found any remnants of the plastidlike heme pathway in the nonphotosynthetic heterokonts Phytophthora ramorum and Phytophthora sojae.
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Affiliation(s)
- Miroslav Oborník
- Department of Botany, University of British Columbia, Vancouver, BC, Canada
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29
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30
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Chaal BK, Green BR. Protein import pathways in 'complex' chloroplasts derived from secondary endosymbiosis involving a red algal ancestor. Plant Mol Biol 2005; 57:333-42. [PMID: 15830125 DOI: 10.1007/s11103-004-7848-y] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2004] [Accepted: 12/17/2004] [Indexed: 05/24/2023]
Abstract
Heterokont algae such as diatoms and the raphidophyte Heterosigma akashiwo and peridinin-containing dinoflagellates such as Heterocapsa triquetra originally acquired their chloroplasts via secondary endosymbiosis involving a red algal endosymbiont and a eukaryote host, resulting in 'complex' chloroplasts surrounded by four and three membranes, respectively. The precursors of both heterokont and dinoflagellate chloroplast-targeted proteins are first inserted into the ER with removal of an N-terminal signal peptide, but how they traverse the remaining membranes is unclear. Using a nuclear-encoded thylakoid lumen protein, PsbO, from the heterokont alga Heterosigma akashiwo, the dinoflagellate Heterocapsa triquetra and the red alga Porphyra yezoensis we show that precursors without the ER signal peptide can be imported into pea chloroplasts. In the case of the H. triquetra and Porphyra PsbO, the precursors were processed to their predicted mature size and localized within the thylakoid lumen, using the Sec-dependent pathway. We report for the first time a stromal processing peptidase (SPP) activity from an alga of the red lineage. The enzyme processes the Heterosigma PsbO precursor at a single site and appears to have different substrate and reaction specificities from the plant SPP. In spite of the fact that we could not find convincing homologs of the plant chloroplast import machinery in heterokont (diatom) and red algal genomes, it is clear that these three very different lines of algae use similar mechanisms to import chloroplast precursors.
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Affiliation(s)
- Balbir K Chaal
- Department of Botany, University of British Columbia, Vancouver, Canada
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31
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Armbrust EV, Berges JA, Bowler C, Green BR, Martinez D, Putnam NH, Zhou S, Allen AE, Apt KE, Bechner M, Brzezinski MA, Chaal BK, Chiovitti A, Davis AK, Demarest MS, Detter JC, Glavina T, Goodstein D, Hadi MZ, Hellsten U, Hildebrand M, Jenkins BD, Jurka J, Kapitonov VV, Kröger N, Lau WWY, Lane TW, Larimer FW, Lippmeier JC, Lucas S, Medina M, Montsant A, Obornik M, Parker MS, Palenik B, Pazour GJ, Richardson PM, Rynearson TA, Saito MA, Schwartz DC, Thamatrakoln K, Valentin K, Vardi A, Wilkerson FP, Rokhsar DS. The Genome of the Diatom Thalassiosira Pseudonana: Ecology, Evolution, and Metabolism. Science 2004; 306:79-86. [PMID: 15459382 DOI: 10.1126/science.1101156] [Citation(s) in RCA: 1158] [Impact Index Per Article: 57.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Diatoms are unicellular algae with plastids acquired by secondary endosymbiosis. They are responsible for approximately 20% of global carbon fixation. We report the 34 million-base pair draft nuclear genome of the marine diatom Thalassiosira pseudonana and its 129 thousand-base pair plastid and 44 thousand-base pair mitochondrial genomes. Sequence and optical restriction mapping revealed 24 diploid nuclear chromosomes. We identified novel genes for silicic acid transport and formation of silica-based cell walls, high-affinity iron uptake, biosynthetic enzymes for several types of polyunsaturated fatty acids, use of a range of nitrogenous compounds, and a complete urea cycle, all attributes that allow diatoms to prosper in aquatic environments.
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Abstract
This is the story of how we started studying the green bands seen on SDS-polyacrylamide gels of thylakoid membranes dissociated with the non-ionic detergent beta-octyl-D-glucopyranoside. We explain some of the complications we and other workers encountered along the pathway to untangling the chlorophyll-protein complexes of higher plants, and give a concise summary of the complexes, their polypeptides and their genes.
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Affiliation(s)
- Edith L Camm
- Biology Department, University College of the Fraser Valley, Abbotsford, British Columbia, Canada
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Abstract
Heterokont algae such as diatoms, brown seaweeds and the raphidophyte Heterosigma akashiwo acquired their chloroplasts via a secondary endosymbiosis involving a red algal endosymbiont and a eukaryote host, resulting in chloroplasts surrounded by four membranes rather than two. The precursor of a nuclear-encoded thylakoid lumen protein, PsbO, from Heterosigma has a presequence composed of a typical ER signal peptide followed by putative stromal and thylakoid targeting domains. A processing enzyme associated with Heterosigma thylakoids cleaved the presequence (with or without the ER signal sequence) in a single step, giving a product of the size of the mature protein. Its sensitivity to a penem inhibitor and insensitivity to other protease inhibitors suggest that it is a member of the Type I signal peptidase family. Furthermore the Heterosigma enzyme appeared to have similar substrate specificity to the pea thylakoidal processing peptidase.
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Affiliation(s)
- Balbir K Chaal
- Department of Botany, University of British Columbia, Vancouver, BC, V6T 1Z4 Canada
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Green BR, Anderson JM, Parson WW. Photosynthetic Membranes and Their Light-Harvesting Antennas. Light-Harvesting Antennas in Photosynthesis 2003. [DOI: 10.1007/978-94-017-2087-8_1] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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Ishida KI, Green BR. Second- and third-hand chloroplasts in dinoflagellates: phylogeny of oxygen-evolving enhancer 1 (PsbO) protein reveals replacement of a nuclear-encoded plastid gene by that of a haptophyte tertiary endosymbiont. Proc Natl Acad Sci U S A 2002; 99:9294-9. [PMID: 12089328 PMCID: PMC123134 DOI: 10.1073/pnas.142091799] [Citation(s) in RCA: 125] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Several dinoflagellate species have plastids that more closely resemble those of an unrelated algal group, the haptophytes, suggesting these plastids have been obtained by tertiary endosymbiosis. Because both groups are photosynthetic, all of the genes for nuclear-encoded plastid proteins might be supplied by the dinoflagellate host or some of them might have been replaced by haptophyte genes. Sequences of the conserved nuclear psbO gene were obtained from the haptophyte Isochrysis galbana, the peridinin-containing dinoflagellate Heterocapsa triquetra, and the 19'hexanoyloxy-fucoxanthin-containing dinoflagellate Karenia brevis. Phylogenetic analysis of the oxygen-evolving-enhancer (PsbO) proteins confirmed that in K. brevis the original peridinin-type plastid was replaced by that of a haptophyte, an alga which had previously acquired a red algal chloroplast by secondary endosymbiosis. It showed clearly that during this tertiary symbiogenesis the original psbO gene in the dinoflagellate nucleus was replaced by a psbO gene from the haptophyte nucleus. The phylogenetic analysis also confirmed that the origin of the peridinin-type dinoflagellate plastid was indeed a red alga.
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Affiliation(s)
- Ken-ichiro Ishida
- Department of Botany, University of British Columbia, Vancouver, BC, Canada V6T 1Z4
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Zhang Z, Cavalier-Smith T, Green BR. Evolution of dinoflagellate unigenic minicircles and the partially concerted divergence of their putative replicon origins. Mol Biol Evol 2002; 19:489-500. [PMID: 11919290 DOI: 10.1093/oxfordjournals.molbev.a004104] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Dinoflagellate chloroplast genes are unique in that each gene is on a separate minicircular chromosome. To understand the origin and evolution of this exceptional genomic organization we completely sequenced chloroplast psbA and 23S rRNA gene minicircles from four dinoflagellates: three closely related Heterocapsa species (H. pygmaea, H. rotundata, and H. niei) and the very distantly related Amphidinium carterae. We also completely sequenced a Protoceratium reticulatum minicircle with a 23S rRNA gene of novel structure. Comparison of these minicircles with those previously sequenced from H. triquetra and A. operculatum shows that in addition to the single gene all have noncoding regions of approximately a kilobase, which are likely to include a replication origin, promoter, and perhaps segregation sequences. The noncoding regions always have a high potential for folding into hairpins and loops. In all six dinoflagellate strains for which multiple minicircles are fully sequenced, parts of the noncoding regions, designated cores, are almost identical between the psbA and 23S rRNA minicircles, but the remainder is very different. There are two, three, or four cores per circle, sometimes highly related in sequence, but no sequence identity is detectable between cores of different species, even within one genus. This contrast between very high core conservation within a species, but none among species, indicates that cores are diverging relatively rapidly in a concerted manner. This is the first well-established case of concerted evolution of noncoding regions on numerous separate chromosomes. It differs from concerted evolution among tandemly repeated spacers between rRNA genes, and that of inverted repeats in plant chloroplast genomes, in involving only the noncoding DNA cores. We present two models for the origin of chloroplast gene minicircles in dinoflagellates from a typical ancestral multigenic chloroplast genome. Both involve substantial genomic reduction and gene transfer to the nucleus. One assumes differential gene deletion within a multicopy population of the resulting oligogenic circles. The other postulates active transposition of putative replicon origins and formation of minicircles by homologous recombination between them.
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Affiliation(s)
- Zhaoduo Zhang
- Department of Botany, University of British Columbia, 3529-6270 University Blvd., Vancouver, BC, Canada V6T 1Z4
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38
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Abstract
Chloroplast genes of several dinoflagellate species are located on unigenic DNA minicircular chromosomes. We have now completely sequenced five aberrant minicircular chromosomes from the dinoflagellate Heterocapsa triquetra. These probably nonfunctional DNA circles lack complete genes, with each being composed of several short fragments of two or three different chloroplast genes and a common conserved region with a tripartite 9G-9A-9G core like the putative replicon origin of functional single-gene circular chloroplast chromosomes. Their sequences imply that all five circles evolved by differential deletions and duplications from common ancestral circles bearing fragments of four genes: psbA, psbC, 16S rRNA, and 23S rRNA. It appears that recombination between separate unigenic chromosomes initially gave intermediate heterodimers, which were subsequently stabilized by deletions that included part or all of one putative replicon origin. We suggest that homologous recombination at the 9G-9A-9G core regions produced a psbA/psbC heterodimer which generated two distinct chimeric circles by differential deletions and duplications. A 23S/16S rRNA heterodimer more likely formed by illegitimate recombination between 16S and 23S rRNA genes. Homologous recombination between the 9G-9A-9G core regions of both heterodimers and additional differential deletions and duplications could then have yielded the other three circles. Near identity of the gene fragments and 9G-9A-9G cores, despite diverging adjacent regions, may be maintained by gene conversion. The conserved organization of the 9G-9A-9G cores alone favors the idea that they are replicon origins and suggests that they may enable the aberrant minicircles to parasitize the chloroplast's replication machinery as selfish circles.
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MESH Headings
- Amino Acid Sequence
- Animals
- Base Sequence
- DNA/chemistry
- DNA/genetics
- DNA, Chloroplast/genetics
- DNA, Circular/genetics
- Dinoflagellida/genetics
- Evolution, Molecular
- Gene Duplication
- Molecular Sequence Data
- Photosynthetic Reaction Center Complex Proteins/genetics
- Photosystem II Protein Complex
- RNA, Ribosomal, 16S/genetics
- RNA, Ribosomal, 23S/genetics
- Sequence Alignment
- Sequence Analysis, DNA
- Sequence Deletion
- Sequence Homology, Amino Acid
- Sequence Homology, Nucleic Acid
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Affiliation(s)
- Z Zhang
- Department of Botany, University of British Columbia, Vancouver, British Columbia, Canada
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39
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Green BR. Was "molecular opportunism" a factor in the evolution of different photosynthetic light-harvesting pigment systems? Proc Natl Acad Sci U S A 2001; 98:2119-21. [PMID: 11226200 PMCID: PMC33384 DOI: 10.1073/pnas.061023198] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
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Zhang Z, Green BR, Cavalier-Smith T. Phylogeny of ultra-rapidly evolving dinoflagellate chloroplast genes: a possible common origin for sporozoan and dinoflagellate plastids. J Mol Evol 2000; 51:26-40. [PMID: 10903370 DOI: 10.1007/s002390010064] [Citation(s) in RCA: 105] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Complete chloroplast 23S rRNA and psbA genes from five peridinin-containing dinoflagellates (Heterocapsa pygmaea, Heterocapsa niei, Heterocapsa rotun-data, Amphidinium carterae, and Protoceratium reticulatum) were amplified by PCR and sequenced; partial sequences were obtained from Thoracosphaera heimii and Scrippsiella trochoidea. Comparison with chloroplast 23S rRNA and psbA genes of other organisms shows that dinoflagellate chloroplast genes are the most divergent and rapidly evolving of all. Quartet puzzling, maximum likelihood, maximum parsimony, neighbor joining, and LogDet trees were constructed. Intersite rate variation and invariant sites were allowed for with quartet puzzling and neighbor joining. All psbA and 23S rRNA trees showed peridinin-containing dinoflagellate chloroplasts as monophyletic. In psbA trees they are related to those of chromists and red algae. In 23S rRNA trees, dinoflagellates are always the sisters of Sporozoa (apicomplexans); maximum likelihood analysis of Heterocapsa triquetra 16S rRNA also groups the dinoflagellate and sporozoan sequences, but the other methods were inconsistent. Thus, dinoflagellate chloroplasts may actually be related to sporozoan plastids, but the possibility of reproducible long-branch artifacts cannot be strongly ruled out. The results for all three genes fit the idea that dinoflagellate chloroplasts originated from red algae by a secondary endosymbiosis, possibly the same one as for chromists and Sporozoa. The marked disagreement between 16S rRNA trees using different phylogenetic algorithms indicates that this is a rather poor molecule for elucidating overall chloroplast phylogeny. We discuss possible reasons why both plastid and mitochondrial genomes of alveolates (Dinozoa, Sporozoa and Ciliophora) have ultra-rapid substitution rates and a proneness to unique genomic rearrangements.
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Affiliation(s)
- Z Zhang
- Department of Botany, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
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41
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Abstract
Photosynthetic dinoflagellates are important aquatic primary producers and notorious causes of toxic 'red tides'. Typical dinoflagellate chloroplasts differ from all other plastids in having a combination of three envelope membranes and peridinin-chlorophyll a/c light-harvesting pigments. Despite evidence of a dinoflagellete satellite DNA containing chloroplast genes, previous attempts to obtain chloroplast gene sequences have been uniformly unsuccessful. Here we show that the dinoflagellate chloroplast DNA genome structure is unique. Complete sequences of chloroplast ribosomal RNA genes and seven chloroplast protein genes from the dinoflagellate Heterocapsa triquetra reveal that each is located alone on a separate minicircular chromosome: 'one gene-one circle'. The genes are the most divergent known from chloroplast genomes. Each circle has an unusual tripartite non-coding region (putative replicon origin), which is highly conserved among the nine circles through extensive gene conversion, but is very divergent between species. Several other dinoflagellate species have minicircular chloroplast genes, indicating that this type of genomic organization may have evolved in ancestral peridinean dinoflagellates. Phylogenetic analysis indicates that dinoflagellate chloroplasts are related to chromistan and red algal chloroplasts and supports their origin by secondary symbiogenesis.
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Affiliation(s)
- Z Zhang
- Canadian Institute for Advanced Research Evolutionary Biology Programme, Department of Botany, University of British Columbia, Vancouver
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Durnford DG, Deane JA, Tan S, McFadden GI, Gantt E, Green BR. A phylogenetic assessment of the eukaryotic light-harvesting antenna proteins, with implications for plastid evolution. J Mol Evol 1999; 48:59-68. [PMID: 9873077 DOI: 10.1007/pl00006445] [Citation(s) in RCA: 207] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
The light-harvesting complexes (LHCs) are a superfamily of chlorophyll-binding proteins present in all photosynthetic eukaryotes. The Lhc genes are nuclear-encoded, yet the pigment-protein complexes are localized to the thylakoid membrane and provide a marker to follow the evolutionary paths of plastids with different pigmentation. The LHCs are divided into the chlorophyll a/b-binding proteins of the green algae, euglenoids, and higher plants and the chlorophyll a/c-binding proteins of various algal taxa. This work examines the phylogenetic position of the LHCs from three additional taxa: the rhodophytes, the cryptophytes, and the chlorarachniophytes. Phylogenetic analysis of the LHC sequences provides strong statistical support for the clustering of the rhodophyte and cryptomonad LHC sequences within the chlorophyll a/c-binding protein lineage, which includes the fucoxanthin-chlorophyll proteins (FCP) of the heterokonts and the intrinsic peridinin-chlorophyll proteins (iPCP) of the dinoflagellates. These associations suggest that plastids from the heterokonts, haptophytes, cryptomonads, and the dinoflagellate, Amphidinium, evolved from a red algal-like ancestor. The Chlorarachnion LHC is part of the chlorophyll a/b-binding protein assemblage, consistent with pigmentation, providing further evidence that its plastid evolved from a green algal secondary endosymbiosis. The Chlorarachnion LHC sequences cluster with the green algal LHCs that are predominantly associated with photosystem II (LHCII). This suggests that the green algal endosymbiont that evolved into the Chlorarachnion plastid was acquired following the emergence of distinct LHCI and LHCII complexes.
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Affiliation(s)
- D G Durnford
- Department of Biology, University of New Brunswick, Mail Service #45111, Fredericton, New Brunswick E3B 6E1, Canada.
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van der Staay GW, Yurkova N, Green BR. The 38 kDa chlorophyll a/b protein of the prokaryote Prochlorothrix hollandica is encoded by a divergent pcb gene. Plant Mol Biol 1998; 36:709-716. [PMID: 9526503 DOI: 10.1023/a:1005930210515] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
The chlorophyll (Chl) a/b proteins of the photosynthetic prokaryotes appear to have evolved by gene duplication and divergence of the core Chl a antenna family, which also includes CP43 and CP47 and the iron-stress induced Chl a-binding IsiA proteins. We show here that Prochlorothrix hollandica has a cluster of three pcb (prochlorophyte chlorophyll b) genes which are co-transcribed. The major antenna polypeptides of 32 and 38 kDa are encoded by pcbA and pcbC respectively. The pcbC gene is significantly divergent from the other two and may have originated by a gene duplication independent of the one that led to isiA and the other prochlorophyte pcb genes. The distant relatedness of the three prochlorophyte genera implies that not only the ability to make Chl b and use it for light-harvesting arose independently in the three lineages, but also that the pcb genes may have arisen as the result of independent gene duplications in each lineage.
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Dinkins RD, Bandaranayake H, Baeza L, Griffiths AJ, Green BR. hcf5, a nuclear photosynthetic electron transport mutant of Arabidopsis thaliana with a pleiotropic effect on chloroplast gene expression. Plant Physiol 1997; 113:1023-31. [PMID: 9112766 PMCID: PMC158225 DOI: 10.1104/pp.113.4.1023] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
A photosynthetic mutant of Arabidopsis thaliana, hcf5, was isolated by screening M2 seedlings for high chlorophyll fluorescence. Thylakoid morphology was strikingly abnormal, with large grana stacks and almost no stroma lamellae. Fluorescence induction kinetics, activity assays, and immunoblotting showed that photosystem II was absent. Polypeptides of the photosystem I complex, the Cyt b6/f complex, coupling factor, and the large subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase were also severely depleted. However, the nuclear-encoded chlorophyll a/b light-harvesting complex polypeptides were unaffected. The rbcL transcript was present at very low levels, the pattern of transcripts from the polycistronic psbB-psbH-petB-petD operon was abnormal, and the mature psbH message was almost completely lacking. This suggests that the hcf5 locus may encode a product required for the correct expression of several chloroplast genes.
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Affiliation(s)
- R D Dinkins
- Department of Botany, University of British Columbia, Vancouver, Canada
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45
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La Roche J, van der Staay GW, Partensky F, Ducret A, Aebersold R, Li R, Golden SS, Hiller RG, Wrench PM, Larkum AW, Green BR. Independent evolution of the prochlorophyte and green plant chlorophyll a/b light-harvesting proteins. Proc Natl Acad Sci U S A 1996; 93:15244-8. [PMID: 8986795 PMCID: PMC26388 DOI: 10.1073/pnas.93.26.15244] [Citation(s) in RCA: 187] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
The prochlorophytes are oxygenic prokaryotes differing from other cyanobacteria by the presence of a light-harvesting system containing both chlorophylls (Chls) a and b and by the absence of phycobilins. We demonstrate here that the Chl a/b binding proteins from all three known prochlorophyte genera are closely related to IsiA, a cyanobacterial Chl a-binding protein induced by iron starvation, and to CP43, a constitutively expressed Chl a antenna protein of photosystem II. The prochlorophyte Chl a/b protein (pcb) genes do not belong to the extended gene family encoding eukaryotic Chl a/b and Chl a/c light-harvesting proteins. Although higher plants and prochlorophytes share common pigment complements, their light-harvesting systems have evolved independently.
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Affiliation(s)
- J La Roche
- Brookhaven National Laboratory, Upton, NY 11973, USA
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46
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Durnford DG, Aebersold R, Green BR. The fucoxanthin-chlorophyll proteins from a chromophyte alga are part of a large multigene family: structural and evolutionary relationships to other light harvesting antennae. Mol Gen Genet 1996; 253:377-86. [PMID: 9003325 DOI: 10.1007/s004380050334] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
A fucoxanthin-chlorophyll protein (FCP) cDNA from the raphidophyte Heterosigma carterae encodes a 210-amino acid polypeptide that has similarity to other FCPs and to the chlorophyll a/b-binding proteins (CABs) of terrestrial plants and green algae. The putative transit sequence has characteristics that resemble a signal sequence. The Heterosigma fcp genes are part of a large multigene family which includes members encoding at least two significantly different polypeptides (Fcp1, Fcp2). Comparison of the FCP sequences to the recently determined three-dimensional structure of the pea LHC II complex indicates that many of the key amino acids thought to participate in the binding of chlorophyll and the formation of complex-stabilizing ionic interactions are well conserved. Phylogenetic analyses of sequences of light-harvesting proteins shows that the FCPs of several chromophyte phyla form a natural group separate from the intrinisic peridinin-chlorophyll proteins (iPCPs) of the dinoflagellates: Although the FCP and CAB genes shared a common ancestor, these lineages diverged from each other prior to the separation of the CAB LHC I and LHC II sequences in the green algae and terrestrial plants.
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Affiliation(s)
- D G Durnford
- Botany Dept., University of British Columbia, Vancouver, Canada
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Funk C, Adamska I, Green BR, Andersson B, Renger G. The nuclear-encoded chlorophyll-binding photosystem II-S protein is stable in the absence of pigments. J Biol Chem 1995; 270:30141-7. [PMID: 8530421 DOI: 10.1074/jbc.270.50.30141] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
The 22-kDa chlorophyll a/b-binding protein (CAB) (psbS gene product) is associated with photosystem II and related to the CAB gene family. Here we report that the PSII-S protein unlike other chlorophyll-binding proteins is stable in the absence of pigments. It is present in etiolated spinach plants and accumulates in the dark progressively with the cellular development of the seedlings. Furthermore, it is present in several pigment-deficient mutants. Analysis of the pigment composition of the PSII-S protein isolated from etiolated plants suggests that neither carotenoids nor chlorophyll precursors are involved in its stabilization in the dark. Exposure of etiolated spinach to light leads to further accumulation of the PSII-S protein, which appears more early than other chlorophyll-binding proteins. Accumulation of the PSII-S protein in green plants is developmentally regulated and restricted to photosynthetic tissues. It is suggested that the function of the PSII-S protein may not be light-harvesting but it could act as a ligand chaperone required for transient binding of pigments during biogenesis or turnover of chlorophyll-binding proteins. Such function would be essential for coordination between pigment biosynthesis and ligation as well as avoiding toxic effects of non-bound chlorophyll molecules.
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Affiliation(s)
- C Funk
- Department of Biochemistry, Arrhenius Laboratories for Natural Sciences, Stockholm University, Sweden
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48
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Green BR, Kühlbrandt W. Sequence conservation of light-harvesting and stress-response proteins in relation to the three-dimensional molecular structure of LHCII. Photosynth Res 1995; 44:139-148. [PMID: 24307033 DOI: 10.1007/bf00018304] [Citation(s) in RCA: 85] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/1995] [Accepted: 02/16/1995] [Indexed: 06/02/2023]
Abstract
The structure of pea light-harvesting complex LHCII determined to 3.4 Å resolution by electron crystallography (Kühlbrandt, Wang and Fujiyoshi (1994) Nature 367: 614-621) was examined to determine the relationship between structural elements and sequence motifs conserved in the extended family of light-harvesting antennas (Chl a/b, fucoxanthin Chl a/c proteins) and membrane-intrinsic stress-induced proteins (ELIPs) to which LHCII belongs. It is predicted that the eukaryotic ELIPs can bind at least four molecules of Chl. The one-helix prokaryotic ELIP of Synechococcus was modelled as a homodimer based on the high degree of conservation of residues involved in the interactions of the first (B) and third (A) helices of LHCII.
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Affiliation(s)
- B R Green
- Department of Botany, University of British Columbia, V6T 1Z4, Vancouver, B.C., Canada
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Affiliation(s)
- M Wallbraun
- Department of Biology, University of Michigan, Ann Arbor 48109
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50
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Green BR. Enabling choice: public health nurses' perceptions of their work with children and families. Nurs Prax N Z 1994; 9:37. [PMID: 7849480] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
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