Activation and reduction of carbon dioxide by nitrogenase iron proteins

The iron protein components of bacterial nitrogenases are capable of reducing carbon dioxide (CO 2 ) to carbon monoxide (CO) in the absence of their catalytic partners, mimicking the activity of CO dehydrogenase. The iron (Fe) proteins of molybdenum (Mo) and vanadium (V) nitrogenases mimic carbon monoxide (CO) dehydrogenase in catalyzing the interconversion between CO 2 and CO under ambient conditions. Catalytic reduction of CO 2 to CO is achieved in vitro and in vivo upon redox changes of the Fe-protein-associated [Fe 4 S 4 ] clusters. These observations establish the Fe protein as a model for investigation of CO 2 activation while suggesting its biotechnological adaptability for recycling the greenhouse gas into useful products.