Extreme desiccation and irradiation increase the formation of reactive oxygen species in organisms. Lichens are highly resistant to potential damage, but it is not known whether biochemical interaction between their fungal and algal partners is involved in conferring stress tolerance. Here, we show that antioxidant and photoprotective mechanisms in the lichen Cladonia vulcani are more effective by orders of magnitude than those of its isolated partners. When alone, both alga and fungus suffer oxidative damage during desiccation, but in the lichen, each appears to induce up-regulation of protective systems in the other. Without the fungal contact, the alga tolerates only very dim light and its photoprotective system is only partially effective; without the alga, the glutathione-based antioxidant system of the fungus is slow and ineffective. In the lichen, this mutually enhanced resistance to oxidative stress and, in particular, its desiccation tolerance are essential for life above ground. This lifestyle, in turn, increases the chance of dispersal of reproductive propagules and ensures their joint evolutionary success.
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http://dx.doi.org/10.1073/pnas.0407716102 | DOI Listing |
Photosynth Res
January 2025
Faculty of Biology, Lomonosov Moscow State University, Moscow, Russia.
The Orange Carotenoid Protein (OCP) is a unique water-soluble photoactive protein that plays a critical role in regulating the balance between light harvesting and photoprotective responses in cyanobacteria. The challenge in understanding OCP´s photoactivation mechanism stems from the heterogeneity of the initial configurations of its embedded ketocarotenoid, which in the dark-adapted state can form up to two hydrogen bonds to critical amino acids in the protein's C-terminal domain, and the extremely low quantum yield of primary photoproduct formation. While a series of experiments involving point mutations within these contacts helped us to identify these challenges, they did not resolve them.
View Article and Find Full Text PDFPhysiol Plant
January 2025
Institute for Plant Molecular and Cell Biology (IBMCP), CSIC-Universitat Politècnica de València, València, Spain.
Plant carotenoids are plastid-synthesized isoprenoids with roles as photoprotectants, pigments, and precursors of bioactive molecules such as the hormone abscisic acid (ABA). The first step of the carotenoid biosynthesis pathway is the production of phytoene from geranylgeranyl diphosphate (GGPP), catalyzed by phytoene synthase (PSY). GGPP produced by plastidial GGPP synthases (GGPPS) is channeled to the carotenoid pathway by direct interaction of GGPPS and PSY enzymes.
View Article and Find Full Text PDFCurr Pharm Biotechnol
January 2025
Research and Scientific Studies Unit, College of Nursing and Allied Health Sciences, Jazan University, Jazan-45142, Saudi Arabia.
Nature has been acknowledged as a fundamental source of diverse bioactive molecules. Among natural carotenoids, lutein, zeaxanthin, and their oxidative metabolites are specifically deposited in the macular region of living organisms. Lutein and zeaxanthin are carotenoids primarily found in green leafy vegetables, eggs, and various fruits.
View Article and Find Full Text PDFArch Microbiol
January 2025
Department of Botany, CMS College Kottayam, Kottayam, Kerala, 686001, India.
Among all photosynthetic life forms, cyanobacteria exclusively possess a water-soluble, light-sensitive carotenoprotein complex known as orange carotenoid proteins (OCPs), crucial for their photoprotective mechanisms. These protein complexes exhibit both structural and functional modularity, with distinct C-terminal (CTD) and N-terminal domains (NTD) serving as light-responsive sensor and effector regions, respectively. The majority of cyanobacterial genomes contain genes for OCP homologs and related proteins, highlighting their essential role in survival of the organism over time.
View Article and Find Full Text PDFNutrients
December 2024
Department of Pharmaceutical Technology, Faculty of Pharmaceutical Sciences and Center of Excellence for Innovation in Chemistry, Naresuan University, Phitsanulok 65000, Thailand.
Background/objectives: UV radiation is a primary cause of skin damage and photoaging. β-carotene, a potent antioxidant, aids in mitigating UV-induced oxidative stress and enhancing skin photoprotection. This research aimed to evaluate the efficacy of a nutraceutical product designed to prevent photoaging.
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