Nav: Home

Even bacteria need their space: Squished cells may shut down photosynthesis

March 23, 2020

Introverts take heart: When cells, like some people, get too squished, they can go into defense mode, even shutting down photosynthesis.

In a study published today, a team at the University of Colorado Boulder took advantage of a new microscopic technique to follow the lives of individual bacteria as they grew and divided in complex colonies.

The researchers discovered something unexpected in the process: Whenever these single-celled organisms, a type of cyanobacteria or blue-green algae, got too smushed, they began to switch off the machinery that was essential for them to turn sunlight into sugar.

The tiny organisms, in other words, slowed down their growth in a big way, said Jeffrey Cameron, an assistant professor in the Department of Biochemistry and coauthor of the new research.

"If a cell is between a rock and a hard place, internally everything says, 'Yes, I have nutrients. I want to grow,'" said Cameron, also of the Renewable and Sustainable Energy Institute (RASEI) at CU Boulder. "But there also has to be a feedback that says, 'I need to turn off photosynthesis so I don't expand and rupture.'"

The findings, which appear in Nature Microbiology, provide a new window on this process that sustains most life on Earth--and, in particular, how organisms regulate photosynthesis when the going gets tough. Cameron hopes that his team's results will also help scientists to develop custom-made microbes that could one day turn light into electricity or even construct living buildings.

Bacterial pancakes

As Cameron explains, it all began almost by accident.

He launched this research several years ago with a deceptively simple goal in mind: He and his colleagues wanted to track the behavior of individual cells within a bacterial colony throughout their entire lifecycle.

That was a difficult feat--for simple-looking organisms, cyanobacteria can form pretty complex structures.

"The cells on the outside of a colony are exposed to a lot of light, while those on the inside have low light exposure," Cameron said. "Over time as they grow and accumulate more cells, they shade themselves."

To be able to see every single cell in a growing colony, Cameron developed a method of culturing cyanobacteria so that they spread out like flat pancakes. When he started peering at these two-dimensional growths under a microscope, he noticed something odd: The more the colonies grew, and the more the bacteria inside began to squeeze together, the more they began to glow, or "fluoresce," under a certain type of light.

The microbes, he explained, were emanating heat out to their environment, almost like a person perspiring on a packed city bus.

"I dropped everything and spent the next four years figuring out what was happening," Cameron said.

The key, he and his colleagues discovered, was that the cells in a colony weren't all glowing the same. The cyanobacteria on the inside of a colony, for example, fluoresced a lot more than those on the fringes. They also grew a lot slower, dividing in two at about half the rate as their exterior cousins.

Put differently, when cells get squished, they shine.

"When the cells become confined, and they can't expand, they become highly fluorescent," Cameron said.

Tiny antennae

So why were those interior cells perspiring so much?

To answer that question, you have to get to know the phycobilisome. This teeny, protein-based structure is the antenna of the cell. Many of these phycobilisomes sit inside cyanobacteria where they collect sunlight, then transport it to the reaction sites where that energy can be converted into glucose, or sugar.

Or that's what usually happens. Cameron and his colleagues found that when their cyanobacteria became too confined, they started to shed their phycobilisomes.

"If the cyanobacteria got more light than they could use for photosynthesis, these antennae would literally pop off," Cameron said.

The microbes couldn't use all that energy, so to keep from getting glutted, they turned off photosynthesis.

The group's results, he said, show just how dynamic single-celled organisms can be: They have a lot of tools for staying healthy in a dynamic social environment.

Understanding that social environment could also one day help scientists put photosynthesis to work--tapping sunlight to design more sustainable buildings or make other biology-based tools.

"We might be able to develop small-scale machines that are using light to perform computations or work," Cameron said.

It's a whole new way to think about catching some rays.
-end-
Other coauthors on the new study include CU Boulder researchers Kristin Moore, a former graduate student in RASEI; Sabina Altus, a graduate student in the Department of Applied Mathematics; Jian Wei Tay, an image analysis specialist in RASEI; Janet Meehl, a professional research assistant in RASEI; Evan Johnson, lab manager; and David Bortz, an associate professor in applied mathematics.

University of Colorado at Boulder

Related Photosynthesis Articles:

Showtime for photosynthesis
Using a unique combination of nanoscale imaging and chemical analysis, an international team of researchers has revealed a key step in the molecular mechanism behind the water splitting reaction of photosynthesis, a finding that could help inform the design of renewable energy technology.
Photosynthesis in a droplet
Researchers develop an artificial chloroplast.
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.
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

Listen Again: Meditations on Loneliness
Original broadcast date: April 24, 2020. We're a social species now living in isolation. But loneliness was a problem well before this era of social distancing. This hour, TED speakers explore how we can live and make peace with loneliness. Guests on the show include author and illustrator Jonny Sun, psychologist Susan Pinker, architect Grace Kim, and writer Suleika Jaouad.
Now Playing: Science for the People

#565 The Great Wide Indoors
We're all spending a bit more time indoors this summer than we probably figured. But did you ever stop to think about why the places we live and work as designed the way they are? And how they could be designed better? We're talking with Emily Anthes about her new book "The Great Indoors: The Surprising Science of how Buildings Shape our Behavior, Health and Happiness".
Now Playing: Radiolab

The Third. A TED Talk.
Jad gives a TED talk about his life as a journalist and how Radiolab has evolved over the years. Here's how TED described it:How do you end a story? Host of Radiolab Jad Abumrad tells how his search for an answer led him home to the mountains of Tennessee, where he met an unexpected teacher: Dolly Parton.Jad Nicholas Abumrad is a Lebanese-American radio host, composer and producer. He is the founder of the syndicated public radio program Radiolab, which is broadcast on over 600 radio stations nationwide and is downloaded more than 120 million times a year as a podcast. He also created More Perfect, a podcast that tells the stories behind the Supreme Court's most famous decisions. And most recently, Dolly Parton's America, a nine-episode podcast exploring the life and times of the iconic country music star. Abumrad has received three Peabody Awards and was named a MacArthur Fellow in 2011.