From Michigan State University: “Michigan State University researchers help reveal a ‘blueprint’ for photosynthesis”

From Michigan State University

8.31.22
Matt Davenport

MSU researchers helped reveal, with nearly atomic precision, the biological structure of an “antenna” used by cyanobacteria for photosynthesis. Knowing the position of different proteins and pigments (shown in different colors) helps researchers better understand this natural process and can inspire future applications in areas such as renewable energy. Credit: Domínguez-Martín et al., Nature (2022)

New findings in microbes called cyanobacteria present new opportunities for plant science, bioengineering and environmental protection.

Michigan State University researchers and colleagues at the University of California-Berkeley, the University of South Bohemia and The DOE’s Lawrence Berkeley National Laboratory have helped reveal the most detailed picture to date of important biological “antennae.”

Nature has evolved these structures to harness the sun’s energy through photosynthesis, but these sunlight receivers don’t belong to plants. They’re found in microbes known as cyanobacteria, the evolutionary descendants of the first organisms on Earth capable of taking sunlight, water and carbon dioxide and turning them into sugars and oxygen.

Published Aug. 31 in the journal Nature [below], the findings immediately shed new light on microbial photosynthesis — specifically, how light energy is captured and sent to where it’s needed to power the conversion of carbon dioxide into sugars. Going forward, the insights could also help researchers remediate harmful bacteria in the environment, develop artificial photosynthetic systems for renewable energy and enlist microbes in sustainable manufacturing that starts with the raw materials of carbon dioxide and sunlight.

“There’s a lot of interest in using cyanobacteria as solar-powered factories that capture sunlight and convert it into a kind of energy that can be used to make important products,” said Cheryl Kerfeld, Hannah Distinguished Professor of structural bioengineering in the College of Natural Science. “With a blueprint like the one we’ve provided in this study, you can start thinking about tuning and optimizing the light-harvesting component of photosynthesis.”

“Once you see how something works, you have a better idea of how you can modify it and manipulate it. That’s a big advantage,” said Markus Sutter, a senior research associate in the Kerfeld Lab, which operates at MSU and Berkeley Lab in California.

For decades, researchers have been working to visualize the different building blocks of phycobilisomes to try to understand how they’re put together. Phycobilisomes are fragile, necessitating this piecemeal approach. Historically, researchers have been unable to get the high-resolution images of intact antennae needed to understand how they 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 cyanobacterial light harvesting antenna is available with nearly atomic resolution. The team included researchers from Michigan State University, Berkeley Lab, the University of California, Berkeley and the University of South Bohemia in the Czech Republic.

“We were fortunate to be a team made up of people with complementary expertise, people who worked well together,” said Kerfeld, who is also a member of the MSU-DOE Plant Research Laboratory, which is supported by the U.S. Department of Energy. “The group had the right chemistry.”

‘A long journey full of nice surprises’

“This work is a breakthrough in the field of photosynthesis,” said Paul Sauer, a postdoctoral researcher in Professor Eva Nogales’ cryogenic electron microscopy lab at The DOE’s Lawrence Berkeley National Laboratory and The University of California-Berkeley.

“The complete light-harvesting structure of a cyanobacteria’s antenna has been missing until now,” Sauer said. “Our discovery helps us understand how evolution came up with ways to turn carbon dioxide and light into oxygen and sugar in bacteria, long before any plants existed on our planet.”

Along with Kerfeld, Sauer is a corresponding author of the new article. The team documented several notable results, including finding a new phycobilisome protein and observing two new ways that the phycobilisome orients its light-capturing rods that hadn’t been resolved before.

“It is 12 pages of discoveries,” said María Agustina Domínguez-Martín of the Nature report. As a postdoctoral researcher in the Kerfeld Lab, Domínguez-Martín initiated the study at Michigan State University and brought it to completion at the Berkeley Lab. She is currently at the University of Cordoba in Spain as part of the Marie Skłowdoska-Curie Postdoctoral Fellowship. “It’s been a long journey full of nice surprises.”

One surprise, for example, came in how a relatively small protein can act as a surge protector for the massive antenna. Before this work, researchers knew the phycobilisome could corral molecules called orange carotenoid proteins, or OCPs, when the phycobilisome had absorbed too much sunlight. The OCPs release the excess energy as heat, protecting a cyanobacterium’s photosynthetic system from burning up.

Until now, there’s been debate about how many OCPs the phycobilisome could bind and where those binding sites were. The new research answers these fundamental questions and offers potentially practical insights.

This kind of surge-protecting system — which is called photoprotection and has analogs in the plant world — naturally tends to be wasteful. Cyanobacteria are slow to turn their photoprotection off after it has done its job. Now, with the complete picture of how the surge protector works, researchers can design ways to engineer “smart,” less wasteful photoprotection, Kerfeld said.

MSU researchers helped uncover an unparalleled level of detail in phycobilisomes, the green and blue assemblies in this illustration. These structures work as antennae that cyanobacteria use in photosynthesis. The blue and green colors represent different proteins and pigments in the phycobilisome. OCPs, the occasional orange hangers-on, help dissipate excess captured energy as heat. Credit: Janet Iwasa/University of Utah.

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

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

“If you think of this like Legos, you can keep building up, right? The proteins and pigments are like blocks making the phycobilisome, but then that’s part of the photosystem, which is in the cell membrane, which is part of the entire cell,” Sutter said. “We’re climbing up the ladder of scale in a way. We’ve found something new on our rung, but we can’t say we’ve got the system settled.”

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

This work was supported by the U.S. 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.

Science paper:
Nature

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Michigan State University is a public research university located in East Lansing, Michigan, United States. Michigan State University was founded in 1855 and became the nation’s first land-grant institution under the Morrill Act of 1862, serving as a model for future land-grant universities.

The university was founded as the Agricultural College of the State of Michigan, one of the country’s first institutions of higher education to teach scientific agriculture. After the introduction of the Morrill Act, the college became coeducational and expanded its curriculum beyond agriculture. Today, Michigan State University is one of the largest universities in the United States (in terms of enrollment) and has approximately 634,300 living alumni worldwide.

U.S. News & World Report ranks its graduate programs the best in the U.S. in elementary teacher’s education, secondary teacher’s education, industrial and organizational psychology, rehabilitation counseling, African history (tied), supply chain logistics and nuclear physics in 2019. Michigan State University pioneered the studies of packaging, hospitality business, supply chain management, and communication sciences. Michigan State University is a member of the Association of American Universities and is classified among “R1: Doctoral Universities – Very high research activity”. The university’s campus houses the National Superconducting Cyclotron Laboratory, the W. J. Beal Botanical Garden, the Abrams Planetarium, the Wharton Center for Performing Arts, the Eli and Edythe Broad Art Museum, the Facility for Rare Isotope Beams, and the country’s largest residence hall system.

Research

The university has a long history of academic research and innovation. In 1877, botany professor William J. Beal performed the first documented genetic crosses to produce hybrid corn, which led to increased yields. Michigan State University dairy professor G. Malcolm Trout improved the process for the homogenization of milk in the 1930s, making it more commercially viable. In the 1960s, Michigan State University scientists developed cisplatin, a leading cancer fighting drug, and followed that work with the derivative, carboplatin. Albert Fert, an Adjunct professor at Michigan State University, was awarded the 2007 Nobel Prize in Physics together with Peter Grünberg.

Today Michigan State University continues its research with facilities such as the Department of Energy -sponsored Plant Research Laboratory and a particle accelerator called the National Superconducting Cyclotron Laboratory [below]. The Department of Energy Office of Science named Michigan State University as the site for the Facility for Rare Isotope Beams (FRIB). The $730 million facility will attract top researchers from around the world to conduct experiments in basic nuclear science, astrophysics, and applications of isotopes to other fields.

Michigan State University FRIB [Facility for Rare Isotope Beams] .

In 2004, scientists at the Cyclotron produced and observed a new isotope of the element germanium, called Ge-60 In that same year, Michigan State University, in consortium with the University of North Carolina at Chapel Hill and the government of Brazil, broke ground on the 4.1-meter Southern Astrophysical Research Telescope (SOAR) in the Andes Mountains of Chile.

NSF NOIRLab NOAO Southern Astrophysical Research [SOAR] telescope, operated by a consortium including the countries of Brazil and Chile, Michigan State University, the Cerro Tololo Inter-American Observatory (CTIO) (part of the National Optical Astronomy Observatory, NOAO), and the University of North Carolina at Chapel Hill situated on Cerro Pachón, just to the southeast of Cerro Tololo, on the NOIRLab NOAO AURA site at an altitude of 2,700 meters (8,775 feet) above sea level.

The consortium telescope will allow the Physics & Astronomy department to study galaxy formation and origins. Since 1999, Michigan State University has been part of a consortium called the Michigan Life Sciences Corridor, which aims to develop biotechnology research in the State of Michigan. Finally, the College of Communication Arts and Sciences’ Quello Center researches issues of information and communication management.

NSCL Nuclear research at Michigan State University National Superconducting Cyclotron Laboratory S800 Spectrograph schematic.

The Michigan State University Spartans compete in the NCAA Division I Big Ten Conference. Michigan State Spartans football won the Rose Bowl Game in 1954, 1956, 1988 and 2014, and the university claims a total of six national football championships. Spartans men’s basketball won the NCAA National Championship in 1979 and 2000 and has attained the Final Four eight times since the 1998–1999 season. Spartans ice hockey won NCAA national titles in 1966, 1986 and 2007. The women’s cross country team was named Big Ten champions in 2019. In the fall of 2019, MSU student-athletes posted all-time highs for graduation success rates and federal graduation rates, according to NCAA statistics.