Protein discovery is important first step in harnessing the power of green algae for agriculture
Algae may hold the key to feeding the world's burgeoning population. Don't worry; no one is going to make you eat them. But because they are more efficient than most plants at taking in carbon dioxide from the air, algae could transform agriculture. If their efficiency could be transferred to crops, we could grow more food in less time using less water and less nitrogen fertilizer.
The algal pyrenoid could be the key to increasing crop yields. A pyrenoid (blue) is seen in a cross-section of an algal cell by false-colored electron microscopy. The pyrenoid sits inside the chloroplast (green), which harvests light energy to drive carbon fixation. Image is courtesy of Moritz Meyer.
Credit: Moritz Meyer
New work from a team led by Carnegie's Martin Jonikas published in Proceedings of the National Academy of Sciences reveals a protein that is necessary for green algae to achieve such remarkable efficiency. The discovery of this protein is an important first step in harnessing the power of green algae for agriculture.
It all starts with the world's most abundant enzyme, Rubisco.
Rubisco "fixes" (or converts) atmospheric carbon dioxide into carbon-based sugars, such as glucose and sucrose, in all photosynthetic organisms on the planet. This reaction is central to life on Earth as we know it, because nearly all the carbon that makes up living organisms was at some point "fixed" from the atmosphere by this enzyme. The rate of this reaction limits the growth rate of many of our crops, and many scientists think that accelerating this reaction would increase crop yields.
The funny thing about Rubisco is that it first evolved in bacteria about 3 billion years ago, a time when the Earth's atmosphere had more abundant carbon dioxide compared to today. As photosynthetic bacteria became more and more populous on ancient Earth, they changed our atmosphere's composition.
"Rubisco functioned very efficiently in the ancient Earth's carbon dioxide-rich environment," Jonikas said. "But it eventually sucked most of the CO2 out of the atmosphere, to the point where CO2 is a trace gas today."
Rubisco is quite literally a victim of its own success. CO2 makes up only about 0.04 percent of molecules in today's atmosphere. In this low concentration of CO2, Rubisco works extremely slowly, which limits the growth rates of many crops.
It turns out that algae have evolved a way to make Rubisco run faster. It's called the pyrenoid. Think of it as a turbocharger for carbon fixation.
The pyrenoid is a tiny compartment inside the cell that is packed with Rubisco and is surrounded by a sheath of starch. Under a microscope, a pyrenoid looks like a spherical bubble inside the cell. Its job is to concentrate carbon dioxide around Rubisco so that Rubisco can run faster.
A pyrenoid provides such a tremendous growth advantage that nearly all algae in the oceans have one. About a third of the planet's carbon fixation is thought to happen in pyrenoids, yet we know almost nothing about how these structures are formed at a molecular level. Such a molecular understanding is needed before researchers can attempt to engineer pyrenoids into crops, which is expected to enhance crop yields by as much as 60 percent.
The research team focused on a fundamental decades-old mystery: what causes Rubisco to cluster at the core of the pyrenoid?
Jonikas and his team discovered that in their model alga Chlamydomonas, this clustering of Rubisco is mediated by a protein they called EPYC1 for Essential Pyrenoid Component 1. They found that EPYC1 bound with Rubisco and packaged it into the matrix of proteins that forms the pyrenoid's interior. What's more, proteins similar to EPYC1 are found in most pyrenoid-containing algae, and are not found in algae that lack these structures.
"A lot of additional work is needed to fully understand EPYC1 and pyrenoids, but our findings are a first step toward engineering algal carbon-capture efficiency into crops," Jonikas said.
The research team also included Carnegie's Luke Mackinder (the lead author), Vivian Chen, Elizabeth Freeman Rosenzweig, Leif Pallesen, Gregory Reeves, and Alan Itakura. The project was a close collaboration with Moritz Meyer, Madeline Mitchell, Oliver Caspari, and Howard Griffiths of the University of Cambridge; Tabea Mettler-Altmann, Frederik Sommer, Timo Mühlhaus, Michael Schroda and Mark Stitt of the Max Planck Institute of Molecular Plant Physiology; Robyn Roth and Ursula Goodenough of Washington University St. Louis; and Stefan Geimer of University of Bayreuth.
This work was funded by the National Science Foundation, the Carnegie Institution for Science, the National Institutes of Health, the Biotechnology and Biological Research Council, and the Federal Ministry of Education and Research in Germany within the framework of the GoFORSYS Research Unit for Systems Biology and the International Max Planck Research School of the Max Planck Society.
The Carnegie Institution for Science is a private, nonprofit organization headquartered in Washington, D.C., with six research departments throughout the U.S. Since its founding in 1902, the Carnegie Institution has been a pioneering force in basic scientific research. Carnegie scientists are leaders in plant biology, developmental biology, astronomy, materials science, global ecology, and Earth and planetary science.
Martin Jonikas | EurekAlert!
Energy crop production on conservation lands may not boost greenhouse gases
13.03.2017 | Penn State
How nature creates forest diversity
07.03.2017 | International Institute for Applied Systems Analysis (IIASA)
Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.
The results will be published on March 22 in the journal „Astronomy & Astrophysics“.
Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...
Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.
Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...
In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...
Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.
Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...
20.03.2017 | Event News
14.03.2017 | Event News
07.03.2017 | Event News
24.03.2017 | Materials Sciences
24.03.2017 | Physics and Astronomy
24.03.2017 | Physics and Astronomy