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Tiny phytoplankton known as diatoms play a significant role in the oceanic ecosystem by absorbing carbon dioxide (CO2) from the atmosphere. They are responsible for capturing up to 20% of the planet’s CO2, making them crucial players in the global carbon cycle. Researchers from the University of Basel in Switzerland have made an important discovery regarding a protein shell found in these algae that is essential for optimizing their CO2 fixation process. This finding could lead to innovative bioengineering methods aimed at mitigating atmospheric CO2 levels.
Though invisible to the naked eye, diatoms are among the most productive algae species in marine environments. Using the process of photosynthesis, they take in substantial amounts of CO2, converting it into organic compounds that serve as vital nutrients for various marine organisms. Despite their ecological importance, the precise mechanisms through which diatoms achieve this high level of efficiency in CO2 utilization have been poorly understood until now.
The investigative team, led by Prof. Ben Engel from the Biozentrum of the University of Basel, in collaboration with scientists from the University of York in the UK and Kwansei Gakuin University in Japan, reported the identification of a protein sheath critical for CO2 fixation in diatoms. Utilizing advanced imaging technologies, particularly cryo-electron tomography (cryo-ET), they successfully mapped the molecular structure of the PyShell protein sheath and elucidated its functional role.
Importance of PyShell in CO2 Fixation
Photosynthesis in plants and algae predominantly occurs within chloroplasts, where sunlight energy is harnessed by thylakoid membranes to assist the enzyme Rubisco in fixing CO2. Diatoms, however, benefit from a unique advantage by clustering their Rubisco utility in specialized structures called pyrenoids, significantly enhancing CO2 capture efficiency.
“We found that diatom pyrenoids are surrounded by a lattice-like protein structure,” explained Dr. Manon Demulder, a co-author of both studies. “The PyShell not only defines the shape of the pyrenoid but also facilitates a concentrated environment for CO2. This setup allows Rubisco to more effectively fix CO2 from the surrounding water and transform it into essential nutrients.”
When scientists experimentally removed the PyShell, they observed a marked decline in the algae’s ability to perform CO2 fixation, leading to decreased rates of photosynthesis and hindered cell growth. “This finding underscores the critical role of the PyShell in carbon capture—a key process for sustaining marine life and influencing the global climate,” Demulder added.
Potential for Biotechnology in CO2 Reduction
The revelation of the PyShell opens promising prospects for biotechnological applications aimed at countering climate change—an urgent issue facing humanity. “First and foremost, it is crucial for us to reduce our existing CO2 emissions to curb the acceleration of climate change. Immediate action is required,” stated Engel.
“The CO2 we release today can persist in the atmosphere for millennia. Our aspiration is that findings like the PyShell will inspire future biotechnology advancements aimed at enhancing photosynthesis and capturing greater amounts of CO2 from the atmosphere. While these aims are long-term, the irreversible nature of CO2 emissions necessitates that we engage in fundamental research now to lay the groundwork for potential carbon-capture innovations in the future.”
Further Reading: Ginga Shimakawa et al, “Diatom pyrenoids are encased in a protein shell that enables efficient CO2 fixation,” Cell (2024). DOI: 10.1016/j.cell.2024.09.013
Onyou Nam et al, “A protein blueprint of the diatom CO2-fixing organelle,” Cell (2024). DOI: 10.1016/j.cell.2024.09.025
Journal Information: Cell Visit Journal Website
Source: University of Basel Visit University Website
Citation: Protein shell discovery reveals how diatoms capture CO₂ so effectively (2024, October 16) retrieved 17 October 2024 from https://phys.org/news/2024-10-protein-shell-discovery-reveals-diatoms.html
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