Researchers help reveal ‘blueprint’ for photosynthesis – ScienceDaily

MSU researchers and colleagues at UC Berkeley, University of Southern Bohemia and Lawrence Berkeley National Laboratory helped uncover the most detailed picture yet of important biological ‘antennas’.

Nature developed these structures to harness the sun’s energy through photosynthesis, but these sunlight receptors do not belong to plants. They are found in microbes known as cyanobacteria, the evolutionary offspring of the first organisms on Earth capable of taking sunlight, water and carbon dioxide and turning them into sugars and oxygen.

Published August 31 in the magazine temper nature, The results immediately shed new light on microbial photosynthesis — specifically, how light energy captures and sends it where it’s needed to convert carbon dioxide into sugars. Going forward, the ideas could also help researchers treat harmful bacteria in the environment, develop artificial photosynthesis systems for renewable energy, and introduce microbes into sustainable manufacturing that starts with raw materials for carbon dioxide and sunlight.

“There is a huge interest in using cyanobacteria as solar-powered plants that capture sunlight and convert it into the kind of energy that can be used to make important products,” said Cheryl Kerfield, senior professor of structural bioengineering in the School of Natural Medicine, Cheryl Kerfield. Sciences. “By using a scheme like the one we presented in this study, you can start thinking about tuning and optimizing the light-harvesting component of photosynthesis.”

said Marcus Sutter, a senior researcher in Kerfield’s lab, who works at Michigan State University and Berkeley Lab in California.

The structures of the blue antennae, called phycobilisomes, are complex assemblies of pigments and proteins, which assemble into relatively huge complexes.

For decades, researchers have been working on visualizing the different building blocks of phycobilisomes to try to understand how they are held together. Phycobilisomes are fragile, necessitating this stepwise approach. Historically, researchers were unable to obtain the high-resolution images of intact antennas needed to understand how to capture and conduct light energy.

Now, thanks to an international team of experts and advances in a technique known as cryo-electron microscopy, the structure of a bacterial light-harvesting antenna is available at nearly atomic resolution. The team included researchers from Michigan State University, Berkeley Lab, University of California, Berkeley, and University of South Bohemia in the Czech Republic.

“We were fortunate to have a team made up of people with complementary experience, people who have worked really well together,” said Kerfield, who is also a member of the MSU-DOE Plant Research Laboratory, which is supported by the US Department of Energy. “The group has the right chemistry.”

A long journey full of beautiful surprises

“This work is a breakthrough in the field of photosynthesis,” said Paul Sawyer, a postdoctoral researcher in Professor Eva Nogales’ cryogenic electron microscopy lab at Berkeley Lab and UC Berkeley.

“The whole light-harvesting structure of the cyanobacterial antenna is missing so far,” Sawyer said. “Our discovery helps us understand how evolution found ways to convert carbon dioxide and light into oxygen and sugar in bacteria, long before there were any plants on our planet.”

Along with Kerfield, Sawyer is a similar author for the new article. The team documented several notable findings, including finding a new phycobilisome protein and observing two new ways to guide the phycobilisome previously unresolved light-capture rods.

“It’s 12 pages of discoveries,” said Maria Augustina Dominguez-Martin of the Nature report. As a postdoctoral researcher in Kerfeld’s lab, Domínguez-Martín began studying at Michigan State University and completed it at Berkeley Lab. She is currently working at the University of Cordoba, Spain as part of the Marie Sk? owdoska-Curie Postdoctoral Fellow. “It has been a long journey full of beautiful surprises.”

One surprise came, for example, in how a relatively small protein could act as a surge protector for a massive antenna. Prior to this work, researchers knew that the phycobilisome could trap molecules called orange carotenoid proteins, or OCPs, when the phycobilisome absorbs too much sunlight. OCPs release excess energy in the form of heat, which protects the cyanobacterial photosynthetic system from burning.

To date, there has been controversy about how many OCPs the phycobilisome can bind to and where those binding sites are. The new research answers these basic questions and offers potential practical insights.

This kind of surge protection system – which is called photoprotection and has analogues in the plant world – naturally tends to be wasteful. Cyanobacteria are slow to stop their photoprotection after they have done their job. Now, with the full picture of how a surge protector works, researchers can design ways to engineer a “smart” photovoltaic shielding that is less wasteful, Kerfield said.

And while helping to make the planet habitable for humans and many other organisms that need oxygen to survive, cyanobacteria have a dark side. Cyanobacteria thrive in lakes, ponds, and reservoirs that can produce deadly toxins for local ecosystems as well as humans and their pets. Having a blueprint for how bacteria not only collect the sun’s energy, but also protect themselves from much of it can inspire new ideas for attacking harmful blooms.

Besides the new answers and potential applications this work offers, researchers are also excited about the new questions it raises and the research it can inspire.

“If you think of this like Legos, you can keep building, right? Proteins and pigments are like the clumps that make the phycobilisome, but that’s part of the photosystem, which is in the cell membrane, and it’s part of the whole cell,” Sutter said. Somehow. We’ve found something new in our grade, but we can’t say we’ve settled the system.”

“We answered some questions, but we opened doors for others, and for me, that’s what makes it a breakthrough,” Dominguez-Martin said. “I’m excited to see how the field develops from here.”

This work was supported by the US Department of Energy, Office of Science, the National Institutes of Health, the Czech Science Foundation, and the European Union’s Horizon 2020 Research and Innovation Program.