A new study reports that a protein used in plant photosynthesis could have originated 2.5 billion years ago in methanogenic microbes – long before oxygen levels rose in Earth’s atmosphere. The research was supported in part by the Exobiology and Evolutionary Biology (Exo/Evo) element of the NASA Astrobiology program.

When studying Methanocaldococcus jannaschii, a methanogen that lives in deep-sea hydrothermal vent environments, the team found a protein called thioredoxin. This protein plays a regulatory role in photosynthesis, but may also help repair damage caused by oxygen in M. jannaschii.

The study could have wide-reaching implications because methanogens play many important roles in the biosphere of Earth. They affect global climate by helping to cycle carbon on our planet. Their natural ability to produce methane from biological material also makes methanogens economically valuable in areas like waste processing and fuel production. Methanogens are also essential for human health. These microbes help to break down food in the large intestine.

The article, “Thioredoxin targets fundamental processes in a methane-producing archaeon, Methanocaldococcus jannaschii,” was published in the Proceedings of the National Academy of Sciences in January, 2014.

Additional funding for this work was provided by the National Science Foundation and the USDA Agricultural Research Service CRIS Project.