Nav: Home

Cryo-EM reveals unexpected diversity of photosystems

March 09, 2020

Oxygenic photosynthesis is the conversion of sunlight into chemical energy that underpins the survival of virtually all complex life forms. The energy conversion is driven by a photosynthetic apparatus that captures light photons in the bioenergetic membranes of cyanobacteria, algae and plants. Photosystem I is a central component of this process.

The current textbook paradigm of Photosystem I is a trimer architecture for cyanobacteria, and a monomer for algae. Two new discoveries from a collaboration of researchers from SciLifeLab with Tsinghua University and Tel Aviv University, reported in Nature Plants, find that freshwater-living plankton Anabaena has adapted a specialized Photosystem I dimer of dimers with 476 pigments; while green alga Dunaliella, has optimized a minimal form of Photosystem I (mini-PSI) to live in hypersaline environment and under light stress. Annemarie Perez Boerema from Alexey Amunts lab (Stockholm University, SciLifeLab) used cryo-EM to visualize the unusual forms of Photosystem I.

The first study on Photosystem I tetramer from Anabaena revealed an increased surface area allowing enrichment of Photosystems in the bioenergetic membrane. This provides an advantage during maturation stages requiring nitrogenase activity. The second study revealed mini-PSI from Dunaliella that features the smallest complex of its kind identified up to date. The scientists also report new energy pathways, pigment binding sites and phospholipids. Unlike all the other known counterparts, the mini-PSI lacks the core protein components that would be involved in interactions with additional light-harvesting partners. This observation suggests previously unknown regulatory mechanism reducing the association of peripheral antennae for environmental acclimatisation.

Together, the two studies show that Photosystems can photosynthesise beyond the textbook description. The discovered configurations in diverged species can be considered as an evolutionary prank that nature makes on occasion, which is promising news for researchers exploring fundamental questions in bioenergetics.
Paper on Photosystem I from Anabaena
Paper on Photosystem I from Dunaliella
Amunts' lab webpage

Science For Life Laboratory

Related Cyanobacteria Articles:

Cyanobacteria as "green" catalysts in biotechnology
Researchers from TU Graz and Ruhr University Bochum show in the journal ACS Catalysis how the catalytic activity of cyanobacteria, also known as blue-green algae, can be significantly increased.
Cyanobacteria from Lake Chad analyzed for toxins
Analysis of dried cyanobacterial cakes from Lake Chad show that they are rich in needed amino acids, but some exceed WHO standards for microcystin, a potent liver toxin.
Uncovering the architecture of natural photosynthetic machinery
Researchers at the University of Liverpool have uncovered the molecular architecture and organisational landscape of thylakoid membranes from a model cyanobacterium in unprecedented detail.
Parasitic fungi keep harmful blue-green algae in check
When a lake is covered with green scums during a warm summer, cyanobacteria -- often called blue-green algae -- are usually involved.
Circadian oscillation of a cyanobacterium doesn't need all three Kai proteins to keep going
Despite conventional understanding that three Kai proteins are required for the circadian oscillation of cyanobacteria, scientists discovered that even when one of them is destroyed, the oscillation is not completely abolished but instead damped.
Even bacteria need their space: Squished cells may shut down photosynthesis
Introverts take heart: When cells, like some people, get too squished, they can go into defense mode, even shutting down photosynthesis.
Method yielding high rate of D-lactate using cyanobacteria could revolutionize bioplastic production
The utilization of bioproduction to synthesize versatile chemical compounds that are usually derived from oil is vital for both the environment and resource sustainability.
Unexpected discovery: Blue-green algae produce oil
Cyanobacteria -- colloquially also called blue-green algae - can produce oil from water and carbon dioxide with the help of light.
Marine cyanobacteria do not survive solely on photosynthesis
The University of Cordoba published a study in a journal from the Nature group that supports the idea that marine cyanobacteria also incorporate organic compounds from the environment.
Cyanobacteria in water and on land identified as source of methane
Cyanobacteria, also known as blue-green algae, are among the most common organisms on Earth.
More Cyanobacteria News and Cyanobacteria Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Listen Again: The Power Of Spaces
How do spaces shape the human experience? In what ways do our rooms, homes, and buildings give us meaning and purpose? This hour, TED speakers explore the power of the spaces we make and inhabit. Guests include architect Michael Murphy, musician David Byrne, artist Es Devlin, and architect Siamak Hariri.
Now Playing: Science for the People

#576 Science Communication in Creative Places
When you think of science communication, you might think of TED talks or museum talks or video talks, or... people giving lectures. It's a lot of people talking. But there's more to sci comm than that. This week host Bethany Brookshire talks to three people who have looked at science communication in places you might not expect it. We'll speak with Mauna Dasari, a graduate student at Notre Dame, about making mammals into a March Madness match. We'll talk with Sarah Garner, director of the Pathologists Assistant Program at Tulane University School of Medicine, who takes pathology instruction out of...
Now Playing: Radiolab

What If?
There's plenty of speculation about what Donald Trump might do in the wake of the election. Would he dispute the results if he loses? Would he simply refuse to leave office, or even try to use the military to maintain control? Last summer, Rosa Brooks got together a team of experts and political operatives from both sides of the aisle to ask a slightly different question. Rather than arguing about whether he'd do those things, they dug into what exactly would happen if he did. Part war game part choose your own adventure, Rosa's Transition Integrity Project doesn't give us any predictions, and it isn't a referendum on Trump. Instead, it's a deeply illuminating stress test on our laws, our institutions, and on the commitment to democracy written into the constitution. This episode was reported by Bethel Habte, with help from Tracie Hunte, and produced by Bethel Habte. Jeremy Bloom provided original music. Support Radiolab by becoming a member today at     You can read The Transition Integrity Project's report here.