Exploring Light-harvesting Antenna in Cyanobacteria

 Seagriculture EU 2024
Light-harvesting Antenna

In this 2018 photo, Himadri Pakrasi, (left) and Annesha Sengupta, a visiting graduate student, examine cyanobacteria in the laboratory. Photo: Joe Angeles/Washington University

Talia Ogliore writes about new research from Washington University, in St. Louis, that reveals the core structure of the light-harvesting antenna of cyanobacteria, or blue-green algae. Their discoveries include key features that both collect energy and block excess light absorption. The study published January 6 in Science Advances, yields insights relevant to future energy applications.

Scientists built a model of the large protein complex called phycobilisome that collects and transmits light energy. Phycobilisomes allow cyanobacteria to take advantage of different wavelengths of light than other photosynthetic organisms, such as green plants on dry land.

This capability significantly increases global productivity from photosynthesis from across the solar energy spectrum — but it is fraught with risk.

“For cyanobacteria, excess light absorption is inevitable — and sometimes lethal,” said Haijun Liu, research scientist in chemistry in Arts & Sciences at Washington University. Dr. Liu is the principal investigator and corresponding author of the new study, funded by the Department of Energy (DOE), Basic Energy Sciences.

“We’ve 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. A high-resolution structure of phycobilisome will allow us to understand such processes in detail.”

Researchers already knew that orange carotenoid protein helps protect cyanobacteria during high light conditions. Though, they did not have a clear picture of all of the structural features at work.

They also did not know where and how orange carotenoid protein is sequestered in a living cyanobacteria cell.

“We were stunned when we first reached the current model,” Dr. Liu said. “We instantly noticed that an inactive orange carotenoid protein can actually get access to – or simply fit snugly in – the free space region between phycobilisome and PSII. PSII is the protein complex that receives energy from phycobilisome for photochemical reactions. Then it is ready to be recruited or activated by environmental cues.”

This structure was assembled by an all-Washington University team of analytical biochemists and structural biologists, including Himadri Pakrasi, the George William and Irene Koechig Freiberg Professor in Arts & Sciences.

The team used structural proteomics in combination with structural modeling to resolve the structure. The method was first developed by Dr. Liu in Dr. Pakrasi’s lab a few years ago, in collaboration with members of a group led by Michael Gross. Dr. Gross is professor of chemistry in Arts & Sciences and of immunology and internal medicine at the School of Medicine. The unique platform they created gave them significant advantages over other labs that had attempted to approach similar biological questions with electron microscope, cryo-electron microscope and other techniques.

The basic science groundwork in this new research helps explain how living organisms maximize photosynthetic efficiency during early events of photosynthesis. The new work will help future efforts to design biohybrid or synthetic systems that harness energy from light.

All rights reserved. Permission required to reprint articles in their entirety. Must include copyright statement and live hyperlinks. Contact david@algaeplanet.com. Algae Planet accepts unsolicited manuscripts for consideration, and takes no responsibility for the validity of claims made in submitted editorial.

Seagriculture USA 2024
AlgaeMetrics

Subscribe

Breaking-News

  • April 22, 2024: New England Kelp Harvest Week, a project started by the Sugar Kelp Collective in 2021, runs from April 20-30 this year. The group of kelp farmers and activists works with restaurants, bakeries, and fish markets to create special dishes and menus that use the sea vegetable, which grows in winter and is harvested in the spring. Across Connecticut, this provides an ideal opportunity for people to explore dishes and cocktails made with kelp. READ MORE...
  • April 19, 2024: Hospitalized COVID-19 patients who took spirulina had a lower risk of death than those who did not, according to results of a randomized controlled trial recently published in Frontiers in Immunology. READ MORE...
  • April 17, 2024: A research team exploring the untapped potential of seaweed farming for carbon sequestration is positioning Taiwan to play a role in offsetting global carbon emissions. READ MORE...
  • April 15, 2024: Somater, a French manufacturer of plastic and polymer primary packaging for cosmetics, pharmaceuticals, food, and industry, has partnered with French start-up Eranova to create a 100% bio-based line of packaging from green algae collected on the banks of a brackish water lagoon near Marseille, in the south of France. READ MORE...

Algae Europe 2024

A Beginner’s Guide