In a recent breakthrough, researchers have uncovered the mechanism used by diatoms to capture carbon dioxide (CO₂) so efficiently that it could help future bioengineering methods mitigate atmospheric CO₂ levels.
Contributing about 20 percent of global CO₂ fixation via photosynthesis, diatoms; the microscopic algae that inhabit the ocean, are shooting past all the Earth’s rainforests combined. In fact, scientists have long been intrigued by this important role in the carbon cycle.
A collaborative study led by Professor Luke Mackinder at the University of York‘s Centre for Novel Agricultural Products, in partnership with Professor Ben Engel’s team at the University of Basel, Switzerland, has identified a protein shell within diatoms that encapsulates the CO₂-fixing enzyme Rubisco. This shell is essential for the algae’s efficient CO₂ fixation.
Using advanced gene editing, protein detection and imaging techniques, the researchers described the molecular architecture of this protein shell, dubbed the PyShell. As published in Cell, their findings show that not only does the PyShell maintain pyrenoid structural integrity, it also enables a high concentration of carbon dioxide for Rubisco to convert carbon dioxide into organic compounds.
However, the implications of this go beyond an understanding of diatom physiology. The insights could be applied to engineering strategies to improve photosynthetic efficiency in other organisms, and help inform methods for atmospheric CO₂ reduction. Professor Mackinder noted,
“Around half of global CO₂ fixation takes place in our oceans by microscopic algae, yet our understanding of how they achieve this multi-billion ton CO₂ fixation process is unclear. Here, we identify a key molecular piece of the ocean carbon fixation ‘jigsaw’ that brings us a step closer to understanding how carbon cycles in our oceans.”
In addition to providing fundamental understanding of diatom biology, this research paves the way toward the development of technologies enabled by natural processes to mitigate environmental problems.
