Superoxide dismutases in photosynthetic organisms: Absence of the cuprozinc enzyme in eukaryotic algae

1977 ◽  
Vol 179 (1) ◽  
pp. 243-256 ◽  
Author(s):  
Kozi Asada ◽  
Sumio Kanematsu ◽  
Kyoko Uchida
Keyword(s):  
Superoxide Dismutases ◽  
Photosynthetic Organisms ◽  
Eukaryotic Algae

Ice-active substances associated with Antarctic freshwater and terrestrial photosynthetic organisms

2000 ◽  
Vol 12 (4) ◽  
pp. 418-424 ◽  
Author(s):  
James A. Raymond ◽  
Christian H. Fritsen
Keyword(s):  
Molecular Weight ◽  
North America ◽  
Ice Crystals ◽  
Dry Valleys ◽  
Cyanobacterial Mats ◽  
Cold Environments ◽  
Photosynthetic Organisms ◽  
Eukaryotic Algae ◽  
Dialysis Membranes ◽  
Active Substances

Macromolecular substances that cause pitting and other modifications of growing ice crystals were found to be associated with cyanobacterial mats, eukaryotic algae and mosses from Ross Island and the McMurdo Dry Valleys, Antarctica. Ice-pitting activities were largely retained by dialysis membranes with molecular weight cut-offs of up to 300 kDa. Unlike most aqueous solutes, the ice-active molecules were not excluded from the ice phase during freezing. The ice-pitting activities of each of the samples tested was destroyed by exposure to temperatures between 45 and 65°C, suggesting that they have a protein component. Ice-active substances were not found in cyanobacteria or mosses from temperate climates, but ice-activity was found to be associated with mosses from cold habitats in North America. Although the function of the ice-active substances is not known, their apparent confinement to cold environments suggests that they have a cryoprotective role.

Superoxide Dismutases in Photosynthetic Organisms

1976 ◽  
pp. 551-564 ◽  
Author(s):  
Kozi Asada ◽  
Sumio Kanematsu ◽  
Masa-aki Takahashi ◽  
Yasuhisa Kona
Keyword(s):  
Superoxide Dismutases ◽  
Photosynthetic Organisms

scholarly journals Structural Diversity of Photosystem I and Its Light-Harvesting System in Eukaryotic Algae and Plants

2021 ◽  
Vol 12 ◽  
Author(s):  
Tianyu Bai ◽  
Lin Guo ◽  
Mingyu Xu ◽  
Lirong Tian
Keyword(s):  
Photosystem I ◽  
Light Harvesting ◽  
Structural Diversity ◽  
Spatial Arrangement ◽  
Oxygenic Photosynthesis ◽  
Light Harvesting Complexes ◽  
X Ray Crystallography ◽  
Photosynthetic Organisms ◽  
Eukaryotic Algae ◽  
Structural Details

Photosystem I (PSI) is one of the most efficient photoelectric apparatus in nature, converting solar energy into condensed chemical energy with almost 100% quantum efficiency. The ability of PSI to attain such high conversion efficiency depends on the precise spatial arrangement of its protein subunits and binding cofactors. The PSI structures of oxygenic photosynthetic organisms, namely cyanobacteria, eukaryotic algae, and plants, have undergone great variation during their evolution, especially in eukaryotic algae and vascular plants for which light-harvesting complexes (LHCI) developed that surround the PSI core complex. A detailed understanding of the functional and structural properties of this PSI-LHCI is not only an important foundation for understanding the evolution of photosynthetic organisms but is also useful for designing future artificial photochemical devices. Recently, the structures of such PSI-LHCI supercomplexes from red alga, green alga, diatoms, and plants were determined by X-ray crystallography and single-particle cryo-electron microscopy (cryo-EM). These findings provide new insights into the various structural adjustments of PSI, especially with respect to the diversity of peripheral antenna systems arising via evolutionary processes. Here, we review the structural details of the PSI tetramer in cyanobacteria and the PSI-LHCI and PSI-LHCI-LHCII supercomplexes from different algae and plants, and then discuss the diversity of PSI-LHCI in oxygenic photosynthesis organisms.

scholarly journals Diffusion barriers and adaptive carbon uptake strategies enhance the modeled performance of the algal CO2-concentrating mechanism

2021 ◽  
Author(s):  
Chenyi Fei ◽  
Alexandra T. Wilson ◽  
Niall M. Mangan ◽  
Ned S. Wingreen ◽  
Martin C. Jonikas
Keyword(s):  
Energy Efficiency ◽  
Reaction Diffusion ◽  
Land Plants ◽  
System Level ◽  
Carbon Uptake ◽  
Carbonic Anhydrases ◽  
Photosynthetic Organisms ◽  
Eukaryotic Algae ◽  
Concentrating Mechanism ◽  
Reaction Diffusion Model

AbstractMany photosynthetic organisms enhance the performance of their CO2-fixing enzyme Rubisco by operating a CO2-concentrating mechanism (CCM). Most CCMs in eukaryotic algae supply concentrated CO2 to Rubisco in an organelle called the pyrenoid. Ongoing efforts seek to engineer an algal CCM into crops that lack a CCM to increase yields. To advance our basic understanding of the algal CCM, we develop a chloroplast-scale reaction-diffusion model to analyze the efficacy and the energy efficiency of the CCM in the green alga Chlamydomonas reinhardtii. We show that achieving an effective and energetically efficient CCM requires a physical barrier such as thylakoid stacks or a starch sheath to reduce CO2 leakage out of the pyrenoid matrix. Our model provides insights into the relative performance of two distinct inorganic carbon uptake strategies: at air-level CO2, a CCM can operate effectively by taking up passively diffusing external CO2 and catalyzing its conversion to HCO3−, which is then trapped in the chloroplast; however, at lower external CO2 levels, effective CO2 concentration requires active import of HCO3−. We also find that proper localization of carbonic anhydrases can reduce futile carbon cycling between CO2 and HCO3−, thus enhancing CCM performance. We propose a four-step engineering path that increases predicted CO2 saturation of Rubisco up to seven-fold at a theoretical cost of only 1.5 ATP per CO2 fixed. Our system-level analysis establishes biophysical principles underlying the CCM that are broadly applicable to other algae and provides a framework to guide efforts to engineer an algal CCM into land plants.Significance StatementEukaryotic algae mediate approximately one-third of CO2 fixation in the global carbon cycle. Many algae enhance their CO2-fixing ability by operating a CO2-concentrating mechanism (CCM). Our model of the algal CCM lays a solid biophysical groundwork for understanding its operation. The model’s consistency with experimental observations supports existing hypotheses about the operating principles of the algal CCM and the functions of its component proteins. We provide a quantitative estimate of the CCM’s energy efficiency and compare the performance of two distinct CO2 assimilation strategies under varied conditions. The model offers a quantitative framework to guide the engineering of an algal CCM into land plants and supports the feasibility of this endeavor.

Four cytosolic-type CuZn-superoxide dismutases in germinating seeds of Pinus sylvestris

1994 ◽  
Vol 92 (3) ◽  
pp. 443-450 ◽  
Author(s):  
Steffen Streller ◽  
Stanislaw Karpinski ◽  
Jan-Erik Hallgren ◽  
Gunnar Wingsle
Keyword(s):  
Pinus Sylvestris ◽  
Superoxide Dismutases ◽  
Germinating Seeds

Identification of genomic islands in Synechococcus sp. WH8102 using genomic barcode and whole-genome microarray analyses

2020 ◽  
Vol 15 ◽  
Author(s):  
Jiahui Pan ◽  
Xizi Luo ◽  
Tong Shao ◽  
Chaoying Li ◽  
Tingting Zhao ◽  
...  
Keyword(s):  
Genomic Islands ◽  
Whole Genome ◽  
Photosynthetic Organisms ◽  
Depth Study ◽  
Whole Genome Microarray ◽  
Integrated Methods ◽  
Synechococcus Sp ◽  
Intuitive View ◽  
Genomic Regions ◽  
Different Origins

Background: Synechococcus sp. WH8102 is one of the most abundant photosynthetic organisms in many ocean regions. Objective: The aim of this study is to identify genomic islands (GIs) in Synechococcus sp. WH8102 with integrated methods. Methods: We have applied genomic barcode to identify the GIs in Synechococcus sp. WH8102, which could make genomic regions of different origins visually apparent. The gene expression data of the predicted GIs was analyzed through microarray data which was collected for functional analysis of the relevant genes. Results: Seven GIs were identified in Synechococcus sp. WH8102. Most of them are involved in cell surface modification, photosynthesis and drug resistance. In addition, our analysis also revealed the functions of these GIs, which could be used for in-depth study on the evolution of this strain. Conclusion: Genomic barcodes provide us with a comprehensive and intuitive view of the target genome. We can use it to understand the intrinsic characteristics of the whole genome and identify GIs or other similar elements.

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