Abstract
Certain anaerobic microorganisms can gain energy and biomass using carbon monoxide or dioxide and dihydrogen as sole sources of carbon and energy. In his Perspective, [Peters][1] explains how new results by Doukov et al. illuminate the carbon dioxide fixation pathway. [Doukov][2] et al . report that the enzyme responsible for the process contains a highly unusual metal cluster, with three different transition metals including copper, in one of its active sites. [1]: http://www.sciencemag.org/cgi/content/full/298/5593/552 [2]: http://www.sciencemag.org/cgi/content/short/298/5593/567