Department of Biology

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In February, Indiana University signed formal partnerships to engage in research collaboration and student exchange with Sorbonne University, one of France's top-ranked research universities. A month later, one of the founding partnerships between the institutions has already borne new fruit.

A study led by David Kehoe of IU Bloomington and Frédéric Partensky of Sorbonne University was recently published in the Proceedings of the National Academy of Sciences, or PNAS. The work, which explains for the first time a key part of a process that allows a widespread ocean bacterium to efficiently convert sunlight into oxygen, is the most recent in a streak of high-profile publications to emerge from a collaboration between their labs over the past 12 years.

"This work is an example of the great partnership between Indiana University and the Sorbonne University to develop research and exchanges between these two leading institutions," said Guillaume Lacroix, the French consul general in Chicago. "It is an agreement that will strengthen the excellence of research and collaboration for the benefit of the academic and student communities. It also provides an opportunity for economic exchanges between France and Indiana, in the fields of innovation, training and investment."

"Great research requires great collaborations," added Rick Van Kooten, vice provost for research and associate vice president for research at IU. "The collaboration between the Kehoe Lab and researchers affiliated with Sorbonne University has been a foundational model for our new partnership, and I'm confident this work is the first of many exciting new discoveries to emerge from the agreements between our institutions."

A molecular geneticist and professor in the IU Bloomington College of Arts and Sciences' Department of Biology, Kehoe studies the molecular processes through which photosynthetic marine plankton sense and respond to changes in their environment. A biologic oceanographer at the Sorbonne-affiliated Biological Research Station of Roscoff, Partensky focuses on identifying the ecological niches and physical locations that these organisms occupy across the world's oceans. Together, they're drawing upon new molecular and ecological data to gain insights into both topics.

"We had almost identical interests and extremely complementary skill sets," added Kehoe, who has co-authored seven papers with Partensky since 2007. "I think that's how the best collaborations are formed. We really respect and appreciate each other's work."

The researchers are both interested in how an ocean bacterium called Synechococcus performs photosynthesis with two different colors of light: blue light in the waters of the deep ocean and green light in shallower coastal waters. It's important to understand these processes since Synechococcus comprise a foundational level of the food chain in Earth's oceans -- as well as produce about 16 percent of the planet's oxygen through the same process that also reduces an equivalent level of carbon dioxide.

"This is an extremely important organism, and much remains to be learned about it," Kehoe said. "Because carbon and oxygen cycles are so important for our planet's heath, everything we can do to understand the inputs and outlets to those cycles is valuable information. This knowledge can help us make more informed models for predicting climate change and global warming."

The new paper reveals a key part of the biological pathway that enables Synechococcusto acclimate to different ocean waters. The researchers and their collaborators identified two different enzymes in the bacteria that compete for the same target site in its cells. If one enzyme attaches to the site, the bacterium better absorbs blue light. If the other attaches, it better absorbs green light. The enzyme present at the higher level influences the color of light the bacterium uses for photosynthesis.

Partensky has also been to IU Bloomington twice: last month and in April 2012.

The first conversation about a partnership between IU and Sorbonne University took place during an official IU trip to Paris in 2017. As one of IU's strongest existing links with the institution, Kehoe later traveled to France with IU Bloomington Provost and Executive Vice President Lauren Robel, IU Vice President for International Affairs Hannah Buxbaum, Van Kooten and eight other senior leaders and faculty members in May 2018. The trip laid the groundwork for the official agreements signed last month.

Additional contributors to the PNAS paper included researchers at the University of New Orleans and IU Bloomington Department of Chemistry's Mass Spectrometry Facility. The work was supported in part by the National Institutes of Health, the National Science Foundation, the French National Research Agency and IU.