show Abstracthide AbstractThe archaeal model organism Methanococcus maripaludis JJ is known to utilize selenium in its primary energy metabolism, the hydrogenotrophic methanogenesis. Selenium is incorporated into selenocysteine-(Sec-) containing enzymes (selenoproteins) which are essential in methanogenesis. In case of a selenium-depleted environment, the type strain M. maripaludis JJ employs a second set of enzymes containing cysteine (Cys) instead of Sec. So far, the genes coding for these Sec-/Cys-containing isoforms are the only genes known with expression influenced by the selenium status of the cell. Utilizing transcriptomics the selenium-responsive regulon has been assessed.