Toggle Accessibility Tools

Identifying a cyanobacterial gene family that helps control photosynthesis

A new Michigan State University study has identified a family of genes in cyanobacteria that help control carbon dioxide fixation. The discovery furthers our basic knowledge of photosynthesis. It also opens new doors to design systems for sustainable biotech production. The research is published in the journal, New Phytologist.

expand iconCyanobacteria and plants share an enzyme in common, rubisco, which captures carbon dioxide from the atmosphere. Carbon capture is the first in a series of reactions that turn carbon into high-energy molecules that feed the planet’s organisms.

In plants, rubisco is often blocked from working by small molecules that attach to it. In response, the protein, Rubisco activase (Rca), comes to the rescue, removing the unwanted molecules so rubisco can work again.

Recent advances in bioinformatics have allowed the lab of Cheryl Kerfeld to identify a cyanobacterial gene that looks like the one that encodes plant rubisco activase.

The new gene encodes what the lab is calling, activase-like cyanobacterial protein (ALC).

“This gene is widespread in many taxonomic groups of cyanobacteria. Those include various unicellular and multi-cellular, filamentous species,” says Sigal Lechno-Yossef, Research Assistant Professor in the Kerfeld lab.

The cyanbacterial ALC’s function remains unknown. The scientists tried mixing the ALC from a model cyanobacterium, Fremyella diplosiphon, with inhibited rubisco from the same organism, in a test tube. The ALC did not relieve rubisco from inhibition by small molecules.

However, in the cell, the protein is physically close to rubisco, just like its plant counterpart is. That is one reason Lechno-Yossef thinks they might work together.

“We also have bioinformatic evidence that shows ALC evolving along with rubisco in cyanobacteria. This finding is further support for interaction between these two proteins,” Lechno-Yossef says.

So if ALC does not unblock rubisco, what does it do?

“We saw ALC causing rubisco proteins to aggregate,” Lechno-Yossef says. “This function is similar to that of another cyanobacterial protein, which is known to contribute to rubisco regulation and localization in the cell.”

There is also evidence ALC helps its host detect CO2 levels in order to adjust photosynthesis rates. When the team deleted the alc gene in a lab cyanobacterium, the organism did not experience dramatic changes in their growth. (In plants, deleting the analogous rubisco activase causes them to starve for carbon, a crucial nutrient.)

However, those same strains experienced morphological changes when grown in CO2-rich environments.

The new research holds promise for the biotech field. In plants, rubisco activase is the focus of much study, as part of efforts to increase rubisco performance. Improving rubisco would lead to plants with higher nutrition contents, and higher crop yields. But such efforts have gone unrewarded so far.

“Cyanobacterial researchers also want to to increase energy yield from photosynthensis,” Lechno-Yossef says. “The goal would be to rewire cyanobacteria’s photosynthetic machine to produce renewable energy compounds or materials for use in medicine or industry.”

“Now we know that cyanobacteria have an enzyme that supports rubisco, we could try making more robust cyanobacteria for industrial applications.”

This work was primarily funded by the US Department of Energy, Office of Basic Energy Sciences. Banner image by Sigal Lechno-Yossef. The research project was a collaboration with Brandon Rohnke and the lab of Beronda Montgomery.


Share this story

Top Stories

Plants and photosynthesis: What's making plants lose their lunch? Plants and photosynthesis: What's making plants lose their lunch?

A new study from Michigan State University is shedding light on how plants could potentially become more efficient at photosynthesis. The long-term implications of this research range from improved agricultural productivity to predicting the effects of climate change.

Josh Vermaas starts faculty position at PRL Josh Vermaas starts faculty position at PRL

Josh Vermaas, the newest addition to the MSU-DOE Plant Research Laboratory faculty body, has begun his assistant professorship this month. Josh is a computational biophysicist whose research interests include developing computational models to better understand membrane processes and plant materials.

Learning what it takes to grow a space garden Learning what it takes to grow a space garden

With the support of NASA, the lab of Federica Brandizzi has been studying how plants survive in space conditions. A new study starts revealing how a plant system – which helps plants manage various types of Earthly stresses, such as extreme heat – might function in space.