Archaea represent the third, and last discovered, domain of life. Our model organisms are Methanosarcina mazei and Methanosarcina acetivorans, which are methanogens belonging to the phylum of Euryarchaeota. Very little is known about the stress regulation or the influence of stress factors like increasing salinities on the metabolism. As methanogens are the biological producers of methane, their reaction to a changing environment plays an important part in understanding future level of methane production. In this dataset we focus on the Na+ homeostasis of M. mazei. In a genetic approach we delete genes probably involved in Na+ homeostasis and investigate the resulting growth phenotype after an osmotic upshock. Preliminary results indicate an important role of Na+/H+ antiporter in the direct answer to increasing salinities. We will determine the intracellular Na+ concentration of the wildtype and the deletion mutants via 22NaCl to address the impact of increasing external salinities on the organisms and the enzyme counteracting. Besides stress regulation we focus on detection of Na+ dependent metabolic enzymes. For this we generate membrane vesicles of M. acetivorans, a marine organism, and measure transport of 22Na+ over the membrane. One important question in this context is the nature of the coupling ion of the ATP synthase, the main energy conserving enzyme of living cells.
