Nav: Home

Photosynthesis -- living laboratories

November 27, 2019

Ludwig-Maximilians-Universitaet (LMU) in Munich biologists Marcel Dann and Dario Leister have demonstrated for the first time that cyanobacteria and plants employ similar mechanisms and key proteins to regulate cyclic electron flow during photosynthesis.

Cyclic electron flow (CEF) is a crucial component of photosynthesis in both plants and cyanobacteria. However, up to now, it was not clear how it differs from, and what components it shares with, the related electron-transport process of linear electron flow (LEF) or how it is regulated. LMU biologists Marcel Dann and Dario Leister have now shown that two specific proteins, called PGRL1 und PGR5, mediate the control of CEF in plants. These proteins had been identified as important elements in photosynthesis in recent years, both in Leister's laboratory and by a group of researchers in Japan. In plants, the amount of biologically useful energy (in the form of ATP) generated by the LEF pathway is insufficient for the synthesis of sugars from carbon dioxide. The ATP produced by cyclic electron flow makes up for this shortfall, and is vital for carbon fixation. This becomes obvious when plants are exposed to stress, have to repair damage caused by high light levels, or are confronted with other deleterious environmental changes. "When CEF is defective, plants very quickly get very sick," Leister says.

Since cyclic electron flow is extremely difficult to measure directly in plants, Dann and Leister turned to cyanobacteria, which also possess a CEF pathway. Cyanobacteria are a very useful model system because the organelles known as chloroplasts - the sites of photosynthesis in plants - were actually derived from them during evolution. The molecular mechanisms that regulate CEF in cyanobacteria are therefore similar to, but significantly less complex than those used by plants, Leister explains. "These are systems that utilize a simpler form of photosynthesis." In their study, which appears in the online journal Nature Communications, the authors introduced the genes that code for the two plant proteins PGRL1 und PGR5 into various mutant strains of these bacteria and analyzed their effects on photosynthesis. "We were quite surprised to find that we could in fact measure something that looked very like cyclic electron transport," says Leister. This finding clearly proves that these two proteins indeed play a key role in cyclic electron flow. In addition, it emerged that they are sufficient to re-establish CEF in mutant cyanobacteria.

This is particularly notable, because cyanobacteria lack PGRL1, although they do have a PGR5-like protein. For this reason, researchers have long wondered why these cells manage to implement CEF with the aid of this PGR5 homolog alone, while the plant pathway requires both PGR5 and PGRL1. The two researchers also found a possible answer to this riddle. They showed that cyanobacteria have a second protein, called Sll1217, which apparently has a function analogous to that of PGRL1 in plants. Although Sll1217 displays only a very low level of structural (i.e. amino-acid sequence) similarity to plant PGRL1, it interacts with PGR5 from both plants and cyanobacteria. Dann and Leister are the first to suggest a function in CEF for Sll1217.

Dario Leister plans to make practical use of these new insights. His latest project, "PhotoRedesign", for which he recently received a Synergy Grant from the European Research Council (ERC), sets out to improve photosynthetic performance and develop ways to enable plants to make better use of sunlight. "We are attempting to beat nature by combining the best elements of different systems of photosynthesis," says Leister. In this respect, the genetically altered cyanobacteria provide new opportunities for further experimentation. "In bacteria, we can experimentally alter the plant version of cyclic electron transport by genetic manipulation within a few weeks," Leister points out. "The altered cyanobacterial strain is like a living laboratory, which allows us to play around with the process of CEF. Such experiments would take years in plants." - And solutions that work in cyanobacteria can then be tried out in plants. "That not only saves lots of time, it allows us to carry out experiments that would be impossible to do in plants."

Ludwig-Maximilians-Universität München

Related Photosynthesis Articles:

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.
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.
Photosynthesis -- living laboratories
Ludwig-Maximilians-Universitaet (LMU) in Munich biologists Marcel Dann and Dario Leister have demonstrated for the first time that cyanobacteria and plants employ similar mechanisms and key proteins to regulate cyclic electron flow during photosynthesis.
Photosynthesis seen in a new light by rapid X-ray pulses
In a new study, led by Petra Fromme and Nadia Zatsepin at the Biodesign Center for Applied Structural Discovery, the School of Molecular Sciences and the Department of Physics at ASU, researchers investigated the structure of Photosystem I (PSI) with ultrashort X-ray pulses at the European X-ray Free Electron Laser (EuXFEL), located in Hamburg, Germany.
Photosynthesis olympics: can the best wheat varieties be even better?
Scientists have put elite wheat varieties through a sort of 'Photosynthesis Olympics' to find which varieties have the best performing photosynthesis.
Strange bacteria hint at ancient origin of photosynthesis
Structures inside rare bacteria are similar to those that power photosynthesis in plants today, suggesting the process is older than assumed.
Just how much does enhancing photosynthesis improve crop yield?
In the next two decades, crop yields need to increase dramatically to feed the growing global population.
Algal library lends insights into genes for photosynthesis
To identify genes involved in photosynthesis, researchers built a library containing thousands of single-celled algae, each with a different gene mutation.
New molecular blueprint advances our understanding of photosynthesis
Researchers at Lawrence Berkeley National Laboratory have used one of the most advanced microscopes in the world to reveal the structure of a large protein complex crucial to photosynthesis, the process by which plants convert sunlight into cellular energy.
Structure and function of photosynthesis protein explained in detail
An international team of researchers has solved the structure and elucidated the function of photosynthetic complex I.
More Photosynthesis News and Photosynthesis 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

Teaching For Better Humans 2.0
More than test scores or good grades–what do kids need for the future? This hour, TED speakers explore how to help children grow into better humans, both during and after this time of crisis. Guests include educators Richard Culatta and Liz Kleinrock, psychologist Thomas Curran, and writer Jacqueline Woodson.
Now Playing: Science for the People

#556 The Power of Friendship
It's 2020 and times are tough. Maybe some of us are learning about social distancing the hard way. Maybe we just are all a little anxious. No matter what, we could probably use a friend. But what is a friend, exactly? And why do we need them so much? This week host Bethany Brookshire speaks with Lydia Denworth, author of the new book "Friendship: The Evolution, Biology, and Extraordinary Power of Life's Fundamental Bond". This episode is hosted by Bethany Brookshire, science writer from Science News.
Now Playing: Radiolab

Dispatch 3: Shared Immunity
More than a million people have caught Covid-19, and tens of thousands have died. But thousands more have survived and recovered. A week or so ago (aka, what feels like ten years in corona time) producer Molly Webster learned that many of those survivors possess a kind of superpower: antibodies trained to fight the virus. Not only that, they might be able to pass this power on to the people who are sick with corona, and still in the fight. Today we have the story of an experimental treatment that's popping up all over the country: convalescent plasma transfusion, a century-old procedure that some say may become one of our best weapons against this devastating, new disease.   If you have recovered from Covid-19 and want to donate plasma, national and local donation registries are gearing up to collect blood.  To sign up with the American Red Cross, a national organization that works in local communities, head here.  To find out more about the The National COVID-19 Convalescent Plasma Project, which we spoke about in our episode, including information on clinical trials or plasma donation projects in your community, go here.  And if you are in the greater New York City area, and want to donate convalescent plasma, head over to the New York Blood Center to sign up. Or, register with specific NYC hospitals here.   If you are sick with Covid-19, and are interested in participating in a clinical trial, or are looking for a plasma donor match, check in with your local hospital, university, or blood center for more; you can also find more information on trials at The National COVID-19 Convalescent Plasma Project. And lastly, Tatiana Prowell's tweet that tipped us off is here. This episode was reported by Molly Webster and produced by Pat Walters. Special thanks to Drs. Evan Bloch and Tim Byun, as well as the Albert Einstein College of Medicine.  Support Radiolab today at