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Marulanda Valencia W, Pandit A. Photosystem II Subunit S (PsbS): A Nano Regulator of Plant Photosynthesis. J Mol Biol 2024; 436:168407. [PMID: 38109993 DOI: 10.1016/j.jmb.2023.168407] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2023] [Revised: 11/26/2023] [Accepted: 12/13/2023] [Indexed: 12/20/2023]
Abstract
Light is required for photosynthesis, but plants are often exposed to excess light, which can lead to photodamage and eventually cell death. To prevent this, they evolved photoprotective feedback mechanisms that regulate photosynthesis and trigger processes that dissipate light energy as heat, called non-photochemical quenching (NPQ). In excess light conditions, the light reaction and activity of Photosystem II (PSII) generates acidification of the thylakoid lumen, which is sensed by special pH-sensitive proteins called Photosystem II Subunit S (PsbS), actuating a photoprotective "switch" in the light-harvesting antenna. Despite its central role in regulating photosynthetic energy conversion, the molecular mechanism of PsbS as well as its interaction with partner proteins are not well understood. This review summarizes the current knowledge on the molecular structure and mechanistic aspects of the light-stress sensor PsbS and addresses open questions and challenges in the field regarding a full understanding of its functional mechanism and role in NPQ.
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Affiliation(s)
| | - Anjali Pandit
- Leiden Inst. of Chemistry, Gorlaeus Laboratory, Einsteinweg 55, 2300 RA Leiden, The Netherlands.
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Messina CM, Arena R, Manuguerra S, Pericot Y, Curcuraci E, Kerninon F, Renda G, Hellio C, Santulli A. Antioxidant Bioactivity of Extracts from Beach Cast Leaves of Posidonia oceanica (L.) Delile. Mar Drugs 2021; 19:560. [PMID: 34677459 PMCID: PMC8539254 DOI: 10.3390/md19100560] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Revised: 09/26/2021] [Accepted: 09/27/2021] [Indexed: 12/11/2022] Open
Abstract
The marine environment is a generous source of biologically active compounds useful for human health. In 50 years, about 25,000 bioactive marine compounds have been identified, with an increase of 5% per year. Peculiar feature of algae and plants is the production of secondary metabolites, such as polyphenols, synthesized as a form of adaptation to environmental stress. Posidonia oceanica is a Mediterranean endemic and dominant seagrass and represents a biologically, ecologically and geologically important marine ecosystem. Within this study, methanolic and ethanolic extracts were generated from fresh and dried Posidonia oceanica leaves, with the aim to employ and valorize the beach cast leaves. The best yield and antioxidant activity (polyphenols content equal to 19.712 ± 0.496 mg GAE/g and DPPH IC50 of 0.090 µg/µL.) were recorded in 70% ethanol extracts (Gd-E4) obtained from leaves dried for two days at 60 °C and ground four times. HPLC analyses revealed the presence of polyphenols compounds (the most abundant of which was chicoric acid) with antioxidant and beneficial properties. Bioactive properties of the Gd-E4 extracts were evaluated in vitro using fibroblast cells line (HS-68), subjected to UV induced oxidative stress. Pre-treatment of cells with Gd-E4 extracts led to significant protection against oxidative stress and mortality associated with UV exposure, thus highlighting the beneficial properties of antioxidants compounds produced by these marine plants against photo damage, free radicals and associated negative cellular effects. Beach cast leaves selection, processing and extraction procedures, and the in vitro assay results suggested the potentiality of a sustainable approach for the biotechnological exploitation of this resource and could serve a model for other marine resources.
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Affiliation(s)
- Concetta Maria Messina
- Laboratorio di Biochimica Marina ed Ecotossicologia, Dipartimento di Scienze Della Terra e del Mare DiSTeM, Università Degli Studi di Palermo, Via G. Barlotta 4, 91100 Trapani, Italy; (R.A.); (S.M.); (E.C.); (A.S.)
| | - Rosaria Arena
- Laboratorio di Biochimica Marina ed Ecotossicologia, Dipartimento di Scienze Della Terra e del Mare DiSTeM, Università Degli Studi di Palermo, Via G. Barlotta 4, 91100 Trapani, Italy; (R.A.); (S.M.); (E.C.); (A.S.)
| | - Simona Manuguerra
- Laboratorio di Biochimica Marina ed Ecotossicologia, Dipartimento di Scienze Della Terra e del Mare DiSTeM, Università Degli Studi di Palermo, Via G. Barlotta 4, 91100 Trapani, Italy; (R.A.); (S.M.); (E.C.); (A.S.)
| | - Yann Pericot
- LEMAR, IRD, CNRS, Ifremer, Université de Brest, F-29280 Plouzane, France; (Y.P.); (F.K.); (C.H.)
| | - Eleonora Curcuraci
- Laboratorio di Biochimica Marina ed Ecotossicologia, Dipartimento di Scienze Della Terra e del Mare DiSTeM, Università Degli Studi di Palermo, Via G. Barlotta 4, 91100 Trapani, Italy; (R.A.); (S.M.); (E.C.); (A.S.)
| | - Fanny Kerninon
- LEMAR, IRD, CNRS, Ifremer, Université de Brest, F-29280 Plouzane, France; (Y.P.); (F.K.); (C.H.)
| | - Giuseppe Renda
- Istituto di Biologia Marina, Consorzio Universitario della Provincia di Trapani, Via G. Barlotta 4, 91100 Trapani, Italy;
| | - Claire Hellio
- LEMAR, IRD, CNRS, Ifremer, Université de Brest, F-29280 Plouzane, France; (Y.P.); (F.K.); (C.H.)
| | - Andrea Santulli
- Laboratorio di Biochimica Marina ed Ecotossicologia, Dipartimento di Scienze Della Terra e del Mare DiSTeM, Università Degli Studi di Palermo, Via G. Barlotta 4, 91100 Trapani, Italy; (R.A.); (S.M.); (E.C.); (A.S.)
- Istituto di Biologia Marina, Consorzio Universitario della Provincia di Trapani, Via G. Barlotta 4, 91100 Trapani, Italy;
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Focsan AL, Polyakov NE, Kispert LD. Photo Protection of Haematococcus pluvialis Algae by Astaxanthin: Unique Properties of Astaxanthin Deduced by EPR, Optical and Electrochemical Studies. Antioxidants (Basel) 2017; 6:E80. [PMID: 29065482 DOI: 10.3390/antiox6040080] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2017] [Revised: 10/17/2017] [Accepted: 10/18/2017] [Indexed: 01/30/2023] Open
Abstract
Abstract The antioxidant astaxanthin is known to accumulate in Haematococcus pluvialis algae under unfavorable environmental conditions for normal cell growth. The accumulated astaxanthin functions as a protective agent against oxidative stress damage, and tolerance to excessive reactive oxygen species (ROS) is greater in astaxanthin-rich cells. The detailed mechanisms of protection have remained elusive, however, our Electron Paramagnetic Resonance (EPR), optical and electrochemical studies on carotenoids suggest that astaxanthin's efficiency as a protective agent could be related to its ability to form chelate complexes with metals and to be esterified, its inability to aggregate in the ester form, its high oxidation potential and the ability to form proton loss neutral radicals under high illumination in the presence of metal ions. The neutral radical species formed by deprotonation of the radical cations can be very effective quenchers of the excited states of chlorophyll under high irradiation.
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Leasure CD, Tong HY, Hou XW, Shelton A, Minton M, Esquerra R, Roje S, Hellmann H, He ZH. root uv-b sensitive mutants are suppressed by specific mutations in ASPARTATE AMINOTRANSFERASE2 and by exogenous vitamin B6. Mol Plant 2011; 4:759-70. [PMID: 21511809 PMCID: PMC3146737 DOI: 10.1093/mp/ssr033] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Vitamin B6 (vitB6) serves as an essential cofactor for more than 140 enzymes. Pyridoxal 5'-phosphate (PLP), active cofactor form of vitB6, can be photolytically destroyed by trace amounts of ultraviolet-B (UV-B). How sun-exposed organisms cope with PLP photosensitivity and modulate vitB6 homeostasis is currently unknown. We previously reported on two Arabidopsis mutants, rus1 and rus2, that are hypersensitive to trace amounts of UV-B light. We performed mutagenesis screens for second-site suppressors of the rus mutant phenotype and identified mutations in the ASPARTATE AMINOTRANSFERASE2 (ASP2) gene. ASP2 encodes for cytosolic aspartate aminotransferase (AAT), a PLP-dependent enzyme that plays a key role in carbon and nitrogen metabolism. Genetic analyses have shown that specific amino acid substitutions in ASP2 override the phenotypes of rus1 and rus2 single mutants as well as rus1 rus2 double mutant. These substitutions, all shown to reside at specific positions in the PLP-binding pocket, resulted in no PLP binding. Additional asp2 mutants that abolish AAT enzymatic activity, but which alter amino acids outside of the PLP-binding pocket, fail to suppress the rus phenotype. Furthermore, exogenously adding vitB6 in growth media can rescue both rus1 and rus2. Our data suggest that AAT plays a role in vitB6 homeostasis in Arabidopsis.
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Affiliation(s)
- Colin D. Leasure
- Department of Biology, 1600 Holloway Avenue, San Francisco State University, San Francisco, CA 94132, USA
- These authors contributed equally to this work
| | - Hong-Yun Tong
- Department of Biology, 1600 Holloway Avenue, San Francisco State University, San Francisco, CA 94132, USA
- These authors contributed equally to this work
| | - Xue-Wen Hou
- Department of Biology, 1600 Holloway Avenue, San Francisco State University, San Francisco, CA 94132, USA
| | - Amy Shelton
- Department of Biology, 1600 Holloway Avenue, San Francisco State University, San Francisco, CA 94132, USA
| | - Mike Minton
- Department of Chemistry and Biochemistry, 1600 Holloway Avenue, San Francisco State University, San Francisco, CA 94132, USA
| | - Raymond Esquerra
- Department of Chemistry and Biochemistry, 1600 Holloway Avenue, San Francisco State University, San Francisco, CA 94132, USA
| | - Sanja Roje
- The Institute of Biological Chemistry, Washington State University, Pullman, WA, 99164, USA
| | - Hanjo Hellmann
- School of Biological Sciences, Washington State University, Pullman, WA, 99164, USA
| | - Zheng-Hui He
- Department of Biology, 1600 Holloway Avenue, San Francisco State University, San Francisco, CA 94132, USA
- To whom correspondence should be addressed. E-mail , tel. (415) 338-6193, fax (415) 338-2295
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