University of Maryland School of Medicine researchers say they've established certain key features in proteins that are needed for life to function on Mars and other extreme environments.
The NASA-funded team studied organisms that survive in the extreme environment of Antarctica. Here, they found small but significant differences between the core proteins in ordinary organisms and those in Haloarchaea, which can tolerate severe conditions such as high salinity, desiccation and extreme temperatures.
While most ordinary organisms contain proteins that are neutral, those in Haloarchaeal microbes are acidic, with their surface covered with negatively charged residues. This keeps proteins in solution, and helps to hold on tightly to water, reversing the effects of high salinity and desiccation.
And the team found more subtle changes in the proteins of one Haloarchaeal species, named Halorubrum lacusprofundi, isolated from a very salty lake in Antarctica. These changes allow them to work in both cold and salty conditions, when temperatures may be well below the freezing point of pure water.
"In such cold temperatures, the packing of atoms in proteins must be loosened slightly, allowing them to be more flexible and functional when ordinary proteins would be locked into inactive conformations" says Dr. DasSarma. "The surface of these proteins also have modifications that loosen the binding of the surrounding water molecules."
"These kinds of adaptations are likely to allow microorganisms like Halorubrum lacusprofundi to survive not only in Antarctica, but elsewhere in the universe," says professor Shiladitya DasSarma.
"For example, there have been recent reports of seasonal flows down the steep sides of craters on Mars suggesting the presence of underground brine pools. Whether microorganisms actually exist in such environments is not yet known, but expeditions like NASA's Curiosity rover are currently looking for signs of life on Mars."