Photosynthetic organisms knock light for fuel, but sometimes there’s too much of a good thing.
New research from Washington University in St. Louis. Louis reveals the basic structure of the light-harvesting antenna of cyanobacteria or blue-green algae – incorporating key features that both collect energy and prevent the absorption of excess light. The study, published Jan. 6 in Advances in science, incorporating perspectives relevant to future energy applications.
Scientists have built a model of the large protein complex called phycobilisome that collects and distributes light energy. Phycobilisomes allow cyanobacteria to take advantage of different light waves than other photosynthetic organisms, such as green plants on dry land.
This potential significantly increases global productivity from photosynthesis from across the solar energy spectrum – but it is full of risk.
“For cyanobacteria, absorbing too much light is inevitable – and sometimes fatal,” said Haijun Liu, a research scientist in chemistry at the Arts & Sciences at the University of Washington. Liu is the lead researcher and corresponding author of the new study, funded by the Department of Energy (DOE), Basic Energy Sciences.
“We have found interesting structural features in the interface where energy is transferred and regulated,” he said. “One of the regulatory processes called non-photochemical quenching is executed by a protein called orange carotenoid protein. The high-resolution structure of a phycobilisome allows us to understand such processes in detail.”
Although researchers already knew that orange carotenoid proteins help protect against cyanobacteria at high light, they did not have a clear picture of all the structural features at work.
They also did not know where and how orange carotenoid proteins are trapped in living cyanobacteria cells.
“We were surprised when we first reached the conventional model,” Liu said. “We immediately noticed that inactive orange carotenoid proteins can enter the free space area between phycobilisome and PSII (the protein complex that receives energy from phycobilisome for photochemical reaction). applied with environmental glue. ”
This structure was compiled by an all-Washington University team of analytical biologists and structural biologists, including Himadri Pakrasi, Professor George William and Irene Koechig Freiberg in Arts & Sciences.
The team used structural proteomics in conjunction with structural modeling to solve the structure. The method was first developed by Liu in a Pakrasi laboratory a few years ago, in collaboration with members of a group led by Michael Gross, professor of chemistry in the Arts & Sciences and immunology and internal medicine at the School of Medicine. The unique platform they created gave them great advantages over other laboratories that had attempted similar biological questions with an electron microscope, a cryo-electron microscope and other methods.
The fundamental scientific work in this new research helps to explain how living organisms increase the efficiency of photosynthesis at early events of photosynthesis. This topic was also supported by the Photosynthetic Antenna Research Center (PARC) at the University of Washington – one of 46 DOE Power Frontiers Research Centers, formerly led by Robert E. Blankenship, Distinguished Lucille P. Markey Professor at Emeritus Arts and Sciences.
The new work will aid future efforts to design biohybrid or synthetic systems that use energy from light.
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