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Ando S, Tanaka R, Ito H. Activity examination of plant Mg-dechelatase and its bacterial homolog in plants and in vitro. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2024; 215:109073. [PMID: 39182428 DOI: 10.1016/j.plaphy.2024.109073] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2024] [Revised: 08/07/2024] [Accepted: 08/22/2024] [Indexed: 08/27/2024]
Abstract
Chlorophyll a serves as a photosynthetic pigment in plants. Its degradation is initiated by the extraction of the central Mg by the Mg-dechelatase enzyme, which is encoded by Stay-Green (SGR). Plant SGR is believed to be derived from bacterial SGR homolog obtained through horizontal gene transfer into photosynthetic eukaryotes. However, it is not known how the bacterial SGR homolog was modified to function in plants. To assess its adaptation mechanism in plants, a bacterial SGR homolog derived from the Anaerolineae bacterium SM23_63 was introduced into plants. It was found that the bacterial SGR homolog metabolized chlorophyll in plants. However, its chlorophyll catabolic activity was lower than that of plant SGR. Recombinant proteins of the bacterial SGR homolog exhibited higher activity than those of the plant SGR. The reduced chlorophyll catabolic activity of bacterial SGR homologs in plants may be associated with low hydrophobicity of the entrance to the catalytic site compared to that of plant SGR. This hinders the enzyme access to chlorophyll, which is localized in hydrophobic environments. This study offers insights into the molecular changes underlying the optimization of enzyme function.
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Affiliation(s)
- Saki Ando
- Graduate School of Environmental Science, Hokkaido University, N10 W5, Sapporo, 060-0810, Japan; Institute of Low Temperature Science, Hokkaido University, N19 W8, Sapporo, 060-0819, Japan
| | - Ryouichi Tanaka
- Institute of Low Temperature Science, Hokkaido University, N19 W8, Sapporo, 060-0819, Japan
| | - Hisashi Ito
- Institute of Low Temperature Science, Hokkaido University, N19 W8, Sapporo, 060-0819, Japan.
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2
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Zhu L, Feng S, Li Y, Sun X, Sui Q, Chen B, Qu K, Xia B. Physiological and transcriptomic analysis reveals the toxic and protective mechanisms of marine microalga Chlorella pyrenoidosa in response to TiO 2 nanoparticles and UV-B radiation. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 912:169174. [PMID: 38072255 DOI: 10.1016/j.scitotenv.2023.169174] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2023] [Revised: 11/28/2023] [Accepted: 12/05/2023] [Indexed: 12/17/2023]
Abstract
Concerns have been raised regarding the adverse effects of nanoparticles (NPs) on marine organisms, as an increasing number of NPs inevitably enter the marine environment with the development of nanotechnology. Owing to the photocatalytic properties, TiO2 NPs' toxicity may be aggravated by enhanced UV-B resulting from stratospheric ozone depletion. However, the molecular mechanisms of phytoplankton in response to TiO2 NPs under UV-B remains poorly understood. In this study, we integrated whole transcriptome analysis with physiological data to provide understanding on the toxic and protective mechanisms of marine Chlorella pyrenoidosa in response to TiO2 NPs under UV-B. The results indicated that the changes in gene expression could be related to the growth inhibition and TiO2 NP internalization in C. pyrenoidosa, and several molecular mechanisms were identified as toxicity response to TiO2 NPs and UV-B. Differential expression of genes involved in glycerophospholipids metabolism indicated that cell membrane disruption allowed TiO2 NPs to enter the algal cell under UV-B exposure, although the up-regulation of genes involved in the general secretory dependent pathway and the ATP-binding cassette transporter family drove cellular secretion of extracellular polymeric substances, acting as a barrier that prevent TiO2 NP internalization. The absence of changes in gene expression related to the antioxidant system may be responsible for the severe oxidative stress observed in algal cells following exposure to TiO2 NPs under UV-B irradiation. Moreover, differential expression of genes involved in pathways such as photosynthesis and energy metabolism were up-regulated, including the light-harvesting, photosynthetic electron transport coupled to photophosphorylation, carbon fixation, glycolysis, pentose phosphate pathway, tricarboxylic acid cycle, and oxidative phosphorylation, indicating that more energy and metabolites were supplied to cope with the toxicity of TiO2 NPs and UV-B. The obtained results provide valuable information on the molecular mechanisms of response of marine phytoplankton exposed to TiO2 NPs and UV-B.
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Affiliation(s)
- Lin Zhu
- State Key Laboratory of Mariculture Biobreeding and Sustainable Goods, Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao 266071, China; Laboratory for Marine Ecology and Environmental Science, Laoshan Laboratory, Qingdao 266237, China
| | - Sulan Feng
- State Key Laboratory of Mariculture Biobreeding and Sustainable Goods, Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao 266071, China; School of Marine Technology and Geomatics, Jiangsu Ocean University, Lianyungang 222005, China
| | - Yu Li
- School of Marine Technology and Geomatics, Jiangsu Ocean University, Lianyungang 222005, China.
| | - Xuemei Sun
- State Key Laboratory of Mariculture Biobreeding and Sustainable Goods, Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao 266071, China; Laboratory for Marine Ecology and Environmental Science, Laoshan Laboratory, Qingdao 266237, China
| | - Qi Sui
- State Key Laboratory of Mariculture Biobreeding and Sustainable Goods, Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao 266071, China; Laboratory for Marine Ecology and Environmental Science, Laoshan Laboratory, Qingdao 266237, China
| | - Bijuan Chen
- State Key Laboratory of Mariculture Biobreeding and Sustainable Goods, Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao 266071, China; Laboratory for Marine Ecology and Environmental Science, Laoshan Laboratory, Qingdao 266237, China
| | - Keming Qu
- State Key Laboratory of Mariculture Biobreeding and Sustainable Goods, Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao 266071, China
| | - Bin Xia
- State Key Laboratory of Mariculture Biobreeding and Sustainable Goods, Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao 266071, China; Laboratory for Marine Ecology and Environmental Science, Laoshan Laboratory, Qingdao 266237, China.
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Kohata R, Lim H, Kanamoto Y, Murakami A, Fujita Y, Tanaka A, Swingley W, Ito H, Tanaka R. Heterologous complementation systems verify the mosaic distribution of three distinct protoporphyrinogen IX oxidase in the cyanobacterial phylum. JOURNAL OF PLANT RESEARCH 2023; 136:107-115. [PMID: 36357749 DOI: 10.1007/s10265-022-01423-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Accepted: 10/31/2022] [Indexed: 06/16/2023]
Abstract
The pathways for synthesizing tetrapyrroles, including heme and chlorophyll, are well-conserved among organisms, despite the divergence of several enzymes in these pathways. Protoporphyrinogen IX oxidase (PPOX), which catalyzes the last common step of the heme and chlorophyll biosynthesis pathways, is encoded by three phylogenetically-unrelated genes, hemY, hemG and hemJ. All three types of homologues are present in the cyanobacterial phylum, showing a mosaic phylogenetic distribution. Moreover, a few cyanobacteria appear to contain two types of PPOX homologues. Among the three types of cyanobacterial PPOX homologues, only a hemJ homologue has been experimentally verified for its functionality. An objective of this study is to provide experimental evidence for the functionality of the cyanobacterial PPOX homologues by using two heterologous complementation systems. First, we introduced hemY and hemJ homologues from Gloeobacter violaceus PCC7421, hemY homologue from Trichodesmium erythraeum, and hemG homologue from Prochlorococcus marinus MIT9515 into a ΔhemG strain of E. coli. hemY homologues from G. violaceus and T. erythraeum, and the hemG homologue of P. marinus complimented the E. coli strain. Subsequently, we attempted to replace the endogenous hemJ gene of the cyanobacterium Synechocystis sp. PCC6803 with the four PPOX homologues mentioned above. Except for hemG from P. marinus, the other PPOX homologues substituted the function of hemJ in Synechocystis. These results show that all four homologues encode functional PPOX. The transformation of Synechocystis with G. violaceus hemY homologue rendered the cells sensitive to an inhibitor of the HemY-type PPOX, acifluorfen, indicating that the hemY homologue is sensitive to this inhibitor, while the wild-type G. violaceus was tolerant to it, most likely due to the presence of HemJ protein. These results provide an additional level of evidence that G. violaceus contains two types of functional PPOX.
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Affiliation(s)
- Ryoya Kohata
- Institute of Low Temperature Science, Hokkaido University, N19W8, Kita-Ku, Sapporo, 060-0819, Japan
| | - HyunSeok Lim
- Institute of Low Temperature Science, Hokkaido University, N19W8, Kita-Ku, Sapporo, 060-0819, Japan
| | - Yuki Kanamoto
- Research Center of Inland Seas, Kobe University, Awaji, 656-2401, Japan
| | - Akio Murakami
- Research Center of Inland Seas, Kobe University, Awaji, 656-2401, Japan
- Department of Biology, Graduate School of Science, Kobe University, Kobe, 657-8501, Japan
| | - Yuichi Fujita
- Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, 464-8601, Japan
| | - Ayumi Tanaka
- Institute of Low Temperature Science, Hokkaido University, N19W8, Kita-Ku, Sapporo, 060-0819, Japan
| | - Wesley Swingley
- Department of Biological Sciences, Northern Illinois University, DeKalb, IL, 60115, USA
| | - Hisashi Ito
- Institute of Low Temperature Science, Hokkaido University, N19W8, Kita-Ku, Sapporo, 060-0819, Japan
| | - Ryouichi Tanaka
- Institute of Low Temperature Science, Hokkaido University, N19W8, Kita-Ku, Sapporo, 060-0819, Japan.
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Tsuzuki Y, Tsukatani Y, Yamakawa H, Itoh S, Fujita Y, Yamamoto H. Effects of Light and Oxygen on Chlorophyll d Biosynthesis in a Marine Cyanobacterium Acaryochloris marina. PLANTS (BASEL, SWITZERLAND) 2022; 11:915. [PMID: 35406896 PMCID: PMC9003380 DOI: 10.3390/plants11070915] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/06/2022] [Revised: 03/22/2022] [Accepted: 03/25/2022] [Indexed: 06/14/2023]
Abstract
A marine cyanobacterium Acaryochloris marina synthesizes chlorophyll (Chl) d as a major Chl. Chl d has a formyl group at its C3 position instead of a vinyl group in Chl a. This modification allows Chl d to absorb far-red light addition to visible light, yet the enzyme catalyzing the formation of the C3-formyl group has not been identified. In this study, we focused on light and oxygen, the most important external factors in Chl biosynthesis, to investigate their effects on Chl d biosynthesis in A. marina. The amount of Chl d in heterotrophic dark-grown cells was comparable to that in light-grown cells, indicating that A. marina has a light-independent pathway for Chl d biosynthesis. Under anoxic conditions, the amount of Chl d increased with growth in light conditions; however, no growth was observed in dark conditions, indicating that A. marina synthesizes Chl d normally even under such “micro-oxic” conditions caused by endogenous oxygen production. Although the oxygen requirement for Chl d biosynthesis could not be confirmed, interestingly, accumulation of pheophorbide d was observed in anoxic and dark conditions, suggesting that Chl d degradation is induced by anaerobicity and darkness.
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Affiliation(s)
- Yuki Tsuzuki
- Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan; (Y.T.); (H.Y.); (Y.F.)
| | - Yusuke Tsukatani
- Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Yokosuka 237-0061, Japan;
| | - Hisanori Yamakawa
- Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan; (Y.T.); (H.Y.); (Y.F.)
| | - Shigeru Itoh
- Graduate School of Science, Nagoya University, Nagoya 464-8601, Japan;
| | - Yuichi Fujita
- Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan; (Y.T.); (H.Y.); (Y.F.)
| | - Haruki Yamamoto
- Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan; (Y.T.); (H.Y.); (Y.F.)
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Chen Y, Yamori W, Tanaka A, Tanaka R, Ito H. Degradation of the photosystem II core complex is independent of chlorophyll degradation mediated by Stay-Green Mg 2+ dechelatase in Arabidopsis. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2021; 307:110902. [PMID: 33902860 DOI: 10.1016/j.plantsci.2021.110902] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2021] [Revised: 03/15/2021] [Accepted: 03/31/2021] [Indexed: 06/12/2023]
Abstract
During leaf senescence, the degradation of photosystems and photosynthetic pigments proceeds in a coordinated manner, which would minimize the potential photodamage to cells. Both photosystem I and II are composed of core complexes and peripheral antenna complexes, with the former binding chlorophyll a and the latter binding chlorophyll a and b. Although the degradation of peripheral antenna complexes is initiated by chlorophyll degradation, it remains unclear whether the degradation of core complexes and chlorophyll is coordinated. In this study, we examined the degradation of peripheral antenna and core complexes in the Arabidopsis sgr1/sgr2/sgrl triple mutant, lacking all the isoforms of chlorophyll a:Mg2+ dechelatase. In this mutant, the degradation of peripheral antenna complexes and photosystem I core complexes was substantially retarded, but the core complexes of photosystem II were rapidly degraded during leaf senescence. On the contrary, the photosynthetic activity declined at a similar rate as in the wild type plants. These results suggest that the degradation of photosystem II core complexes is regulated independently of the major chlorophyll degradation pathway mediated by the dechelatase. The study should contribute to the understanding of the complex molecular mechanisms underlying the degradation of photosystems, which is an essential step during leaf senescence.
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Affiliation(s)
- Ying Chen
- Institute of Low Temperature Science, Hokkaido University, Sapporo, Japan
| | - Wataru Yamori
- Institute for Sustainable Agro-Ecosystem Services, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Ayumi Tanaka
- Institute of Low Temperature Science, Hokkaido University, Sapporo, Japan
| | - Ryouichi Tanaka
- Institute of Low Temperature Science, Hokkaido University, Sapporo, Japan
| | - Hisashi Ito
- Institute of Low Temperature Science, Hokkaido University, Sapporo, Japan.
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Suehiro H, Tanaka R, Ito H. Distribution and functional analysis of the two types of 8-vinyl reductase involved in chlorophyll biosynthesis in marine cyanobacteria. Arch Microbiol 2021; 203:3565-3575. [PMID: 33956163 DOI: 10.1007/s00203-021-02348-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Revised: 04/20/2021] [Accepted: 04/22/2021] [Indexed: 10/21/2022]
Abstract
In the chlorophyll biosynthesis pathway, the 8-vinyl group of the chlorophyll precursor is reduced to an ethyl group by 8-vinyl reductase. Two isozymes of 8-vinyl reductase have been described in oxygenic photosynthetic organisms: one encoded by BciA and another by BciB. Only BciB contains an [Fe-S] cluster and most cyanobacteria harbor this form; whereas a few contain BciA. Given this disparity in distribution, cyanobacterial BciA has remained largely overlooked, which has limited understanding of chlorophyll biosynthesis in these microorganisms. Here, we reveal that cyanobacterial BciA encodes a functional 8-vinyl reductase, as evidenced by measuring the in vitro activity of recombinant Synechococcus and Acaryochloris BciA. Genomic comparison revealed that BciB had been replaced by BciA during evolution of the marine cyanobacterium Synechococcus, and coincided with replacement of Fe-superoxide dismutase (SOD) with Ni-SOD. These findings imply that the acquisition of BciA confers an adaptive advantage to cyanobacteria living in low-iron oceanic environments.
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Affiliation(s)
- Haruka Suehiro
- Institute of Low Temperature Science, Hokkaido University, Sapporo, Japan
| | - Ryouichi Tanaka
- Institute of Low Temperature Science, Hokkaido University, Sapporo, Japan
| | - Hisashi Ito
- Institute of Low Temperature Science, Hokkaido University, Sapporo, Japan.
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Luo SW, Alimujiang A, Balamurugan S, Zheng JW, Wang X, Yang WD, Cui J, Li HY. Physiological and molecular responses in halotolerant Dunaliella salina exposed to molybdenum disulfide nanoparticles. JOURNAL OF HAZARDOUS MATERIALS 2021; 404:124014. [PMID: 33069998 DOI: 10.1016/j.jhazmat.2020.124014] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Revised: 08/19/2020] [Accepted: 09/14/2020] [Indexed: 06/11/2023]
Abstract
Molybdenum disulfide nanoparticles (MoS2 NPs) has emerged as the promising nanomaterial with a wide array of applications in the biomedical, industrial and environmental field. However, the potential effect of MoS2 NPs on marine organisms has yet to be reported. In this study, the effect of MoS2 NPs on the physiological index, subcellular morphology, transcriptomic profiles of the marine microalgae Dunaliella salina was investigated for the first time. exhibited "doping-like" effects on marine microalgae; Growth stimulation was 193.55%, and chlorophyll content increased 1.61-fold upon the addition of 50 μg/L MoS2 NPs. Additionally, exposure to MoS2 NPs significantly increased the protein and carbohydrate content by 2.03- and 1.56-fold, respectively. The antioxidant system was activated as well to eliminate the adverse influence of reactive oxygen species (ROS). Transcriptomic analysis revealed that genes involved in porphyrin synthesis, glycolysis/gluconeogenesis, tricarboxylic acid cycle and DNA replication were upregulated upon MoS2 NPs exposure, which supports the mechanistic role of MoS2 NPs in improving cellular growth and photosynthesis. The "doping-like" effects on marine algae suggest that the low concentration of MoS2 NPs might change the rudimentary ecological composition in the ocean.
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Affiliation(s)
- Shan-Wei Luo
- Key Laboratory of Eutrophication and Red Tide Prevention of Guangdong Higher Education Institutes, College of Life Science and Technology, Jinan University, Guangzhou 510632, China
| | - Adili Alimujiang
- Key Laboratory of Eutrophication and Red Tide Prevention of Guangdong Higher Education Institutes, College of Life Science and Technology, Jinan University, Guangzhou 510632, China
| | - Srinivasan Balamurugan
- Key Laboratory of Eutrophication and Red Tide Prevention of Guangdong Higher Education Institutes, College of Life Science and Technology, Jinan University, Guangzhou 510632, China
| | - Jian-Wei Zheng
- Key Laboratory of Eutrophication and Red Tide Prevention of Guangdong Higher Education Institutes, College of Life Science and Technology, Jinan University, Guangzhou 510632, China
| | - Xiang Wang
- Key Laboratory of Eutrophication and Red Tide Prevention of Guangdong Higher Education Institutes, College of Life Science and Technology, Jinan University, Guangzhou 510632, China
| | - Wei-Dong Yang
- Key Laboratory of Eutrophication and Red Tide Prevention of Guangdong Higher Education Institutes, College of Life Science and Technology, Jinan University, Guangzhou 510632, China
| | - Jianghu Cui
- National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China, Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and Management, Institute of Eco-environmental and Soil Sciences, Guangdong Academy of Sciences, Guangzhou 510650, China.
| | - Hong-Ye Li
- Key Laboratory of Eutrophication and Red Tide Prevention of Guangdong Higher Education Institutes, College of Life Science and Technology, Jinan University, Guangzhou 510632, China.
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