Nitrogenase-like Biosynthesis of (Bacterio)chlorophylls

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The photosynthetic capture of the global energy demand vitally depends on the biosynthesis of (bacterio)chlorophylls. Also the reduction of atmospheric dinitrogen to ammonia is essential for the fuelling of ecosystems. The sophisticated biochemistry of nitrogenase plays a fundamental role for the formation of chlorophylls and bacteriochlorophylls. The biosynthesis of both, chlorophylls and bacteriochlorophylls requires the stereospecific reduction of the C17-C18 double bond of ring D of protochlorophyllide which can be catalyzed by the nitrogenase-like enzyme dark-operative protochlorophyllide oxidoreductase (DPOR). The biosynthesis of all Bchls requires a second nitrogenase-like enzyme termed chlorophyllide oxidoreductase (COR) for the stereospecific reduction of the C7-C8 position of chlorophyllide. Here we want to elucidate the catalytic differences between COR, DPOR and nitrogenase. We intend to resolve the three-dimensional structure of the substrate-bound COR complex. Furthermore, we intend to identify the artificial small molecule substrate spectrum of COR. These results will help to further understand the recently discovered CO reducing capacity of nitrogenase which facilitates the formation of small hydrocarbons.