Phycobilisome (PBS) structures are elaborate antennae in cyanobacteria and red algae. These large protein complexes capture incident sunlight and transfer the energy through a network of embedded pigment molecules called bilins to the photosynthetic reaction centres. However, light harvesting must also be balanced against the risks of photodamage. A known mode of photoprotection is mediated by orange carotenoid protein (OCP), which binds to PBS when light intensities are high to mediate photoprotective, non-photochemical quenching. Here we use cryogenic electron microscopy to solve four structures of the 6.2 MDa PBS, with and without OCP bound, from the model cyanobacterium Synechocystis sp. PCC 6803. The structures contain a previously undescribed linker protein that binds to the membrane-facing side of PBS. For the unquenched PBS, the structures also reveal three different conformational states of the antenna, two previously unknown. The conformational states result from positional switching of two of the rods and may constitute a new mode of regulation of light harvesting. Only one of the three PBS conformations can bind to OCP, which suggests that not every PBS is equally susceptible to non-photochemical quenching. In the OCP-PBS complex, quenching is achieved through the binding of four 34 kDa OCPs organized as two dimers. The complex reveals the structure of the active form of OCP, in which an approximately 60 Å displacement of its regulatory carboxy terminal domain occurs. Finally, by combining our structure with spectroscopic properties, we elucidate energy transfer pathways within PBS in both the quenched and light-harvesting states. Collectively, our results provide detailed insights into the biophysical underpinnings of the control of cyanobacterial light harvesting. The data also have implications for bioengineering PBS regulation in natural and artificial light-harvesting systems.
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http://dx.doi.org/10.1038/s41586-022-05156-4 | DOI Listing |
J Phys Chem Lett
January 2025
Key Laboratory of Advanced Light Conversion Materials and Biophotonics, School of Chemistry and Life Resources, Renmin University of China, Beijing 100872, P. R. China.
Chlorophyll (Chl) is the most abundant light-harvesting pigment of oxygenic photosynthetic organisms; however, the Q-band energetics and relaxation dynamics remain unclear. In this work, we have applied femtosecond time-resolved (-TA) absorption spectroscopy in 430-1,700 nm to Chls and in diluted pyridine solutions under selective optical excitation within their Q-bands. The results revealed distinct near-infrared absorption features of the B ← Q and B ← Q transitions in 930-1,700 nm, which together with the steady-state absorption in 400-700 nm unveiled the Q-state energy that lies 1,000 ± 400 and 600 ± 400 cm above the Q-state for Chls and , respectively.
View Article and Find Full Text PDFACS Appl Mater Interfaces
January 2025
State Key Laboratory of Powder Metallurgy, Central South University, Changsha, Hunan 410083, China.
Porous piezoelectric materials have attracted much interest in the fields of sensing and energy harvesting owing to their low dielectric constant, high piezoelectric voltage coefficient, and energy harvesting figure of merit. However, the introduction of porosity can decrease the piezoelectric coefficient, which restricts the enhancement of output current and power density. Herein, to overcome these challenges, an array-structured piezoelectric composite energy harvester with aligned porosity was constructed via a dual structure design strategy to enhance the output current and power density.
View Article and Find Full Text PDFChem Asian J
January 2025
Birla Institute of Technology & Science Pilani - Hyderabad Campus, Chemistry, INDIA.
Hot-exciton materials, among all kinds of organic light-emitting diode (OLED) emitters, have better exciton utilization efficiency and efficiency roll-off, making them possible for their practical applications. We studied the photophysical properties of a few hot-exciton molecules based on an anthracene core unit to efficiently harvest all triplet excitons to the lowest excited singlet state. The conversion of triplet exciton to singlet exciton utilizing hRISC can be enhanced due to the 1ππ*←3nπ* transition channel.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
January 2025
Nankai University, School of Materials Science and Engineering, National Institute for Advanced Materials, TKL of Metal and Molecule-Based Material Chemistry, CHINA.
Efficient utilization of solar energy is widely regarded as a crucial solution to addressing the energy crisis and reducing reliance on fossil fuels. Coupling photothermal and photochemical conversion can effectively improve solar energy utilization yet remains challenging. Here, inspired by the photosynthesis system in green plants, we report herein an artificial solar energy converter (ASEC) composed of light-harvesting units as solar collector and oriented ionic hydrophilic channels as reactors and transporters.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
January 2025
Material Science Division, Argonne National Laboratory, 9700 South Cass Avenue, Lemont, Illinois, 60439, United States.
Exposure of soft material templates to alternating volatile chemical precursors can produce inorganic deposition within the permeable template (e.g. a polymer thin film) in a process akin to atomic layer deposition (ALD).
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