Dr. Oscar Millet at CIC bioGUNE

A group of research scientists from the Centre for Cooperative Research in Biosciences, CIC bioGUNE, led by Dr. Oscar Millet has discovered the mechanisms that explain the strange ability of some proteins to adapt to hostile and extreme environments, in particular those of high salinity. The research was recently published in the prestigious journal Plos Biology.

Life on earth has an enormous capability to adapt to the environment, and living things inhabit even the most inhospitable places. Halophilic archaea are single-celled organisms that live in salt marshes and lakes, where the high concentration of salt would burst a normal cell. To avoid osmotic shock, the archaea balance the interior salt concentration of the cell with that of their surroundings.

The researchers on the project have used high-resolution techniques from the Structural Biology Unit of CIC bioGUNE, such as nuclear magnetic resonance (NMR) and circular dichroism, on a series of proteins to establish the structural and thermodynamic bases of the mechanism for adapting to highly saline environments.

They have thus been able to understand the relationship between the composition of amino acids and their adaptation to salt. In environments of high salinity, the concentration of water is reduced and the amino acids accumulate on the surface, minimising interaction with the water. “We have answered a difficult question that had been around for 15 or 20 years without a solution”, declared Dr. Millet, who remembers that this enigma has been the object of research for many years by various research groups in USA and Israel. Research in the latter country was primarily because of proximity to the Dead Sea.

“The thing to understand first is the interaction with the solvent, i.e. that it reduces its interaction with the watery environment. If you have protein in a watery medium, the water solubilises the protein. But if you have salt in the medium, the water has to share its function; it has to dissolve the salt and the protein as well. This means that the protein has to lose contacts. And this particular composition of amino acids allows itself to lose contacts without great damage to the conformational stability of the protein. This is the crux of the matter”, explained Millet.

The main application that this scientific discovery may have is in enzyme engineering, as Dr. Millet thinks that in bioreactors there are “conditions of scarcity of water that are similar to saline environments”.

In short, use could be made of this find in biotechnology, in particular in the industrial use of biological substances that allow companies to meet the precepts of “green chemistry”, to reduce toxic emissions and even reduce the emission of greenhouse gases, by using techniques that contribute to the reduction of the energy needed for industrial processes.