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UM News
March 26, 2013


Researchers in The University of Montana Division of Biological Sciences are beginning unlock the mysteries underlying the unique innovation of photosynthetic bacterial life at extreme temperatures.

Every year, millions of visitors to Yellowstone National Park traverse the boardwalk of Grand Prismatic Hot Spring to witness one of life’s major transitions. Near boiling point at the pool’s blue center, the microbial food web is powered by hydrogen. But where the water has cooled to about 165 degrees Fahrenheit, colorful microbial mats of the cyanobacterium Synechococcus develop and support a more diverse and productive community which is fueled by sunlight.

This transition marks the temperature limit for organisms using photosynthesis as a way of survival. In an article titled “The Evolution of RuBisCO Stability at the Thermal Limit of Photoautotrophy,” which will be published in the next issue of Molecular Biology and Evolution, lead author and UM Associate Professor Scott Miller explores a protein central to this extreme lifestyle.

Grand Prismatic Hot Spring in Yellowstone National Park Cyanobacteria ­– also called blue-green algae – grow using the same cellular machinery as plants, including the enzyme RuBisCO, which converts carbon dioxide to sugar. Miller and co-authors UM Associate Professor Michele McGuirl and Research Assistant Darla Carvey uncovered the roots of RuBisCO stability and function at higher temperatures.

By studying the properties of the enzyme in modern Synechococcus bacteria, as well as ancestral versions of RuBisCO that were “resurrected” using molecular biological tools, the research team discovered four evolutionary changes that have contributed to the origins of this unique, light-driven ecosystem. The work also provides general insights on the most abundant protein on the planet.

“Understanding RuBisCOs from these microorganisms from extreme environments teaches us new things about the structure and function of this agriculturally and environmentally important enzyme,” Miller said.

The article is available online at and will be published in the April 1 issue of Molecular Biology and Evolution. For more information call Miller at 406-243-5149 or email


Photo caption: Grand Prismatic Hot Spring in Yellowstone National Park is home to the cyanobacterium Synechococcus, which survives in the extremely hot environment through photosynthesis. (National Park Service photo by Jim Peaco.)



State, National Science


Contact: Scott Miller, associate professor, UM Division of Biological Sciences, 406-243-5149,