The regulatory network of nitrogen assimilation and fixation in the methanogenic Archaeon Methanosarcina mazei strain Gö1

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The mesophilic methanogenic Archaeon Methanosarcina mazei strain Gö1 is able to fix molecular nitrogen when growing under nitrogen-limited conditions. Analyzing the sequence of the genome we have identified and characterized the genes encoding the molybdenum-containing nitrogenase. With this project we seek to analyze the regulatory network of nitrogen metabolism in Ms. mazei using classical genetic approaches and modern molecular tools arising from the knowledge of the complete genome sequence. The first major goal is to identify and to characterize genes, which are regulated by ammonium, using 2-dimensional gel electrophoresis and northern blot analyses. The second goal is to analyze regulatory elements of the nitrogen regulon using two strategies: (i) comparative promoter analyses of the identified nitrogen regulated genes and (ii) identification of promoter binding proteins from cells grown at different nitrogen availabilities by affinity chromatography and gel retardation assays using the identified nitrogen regulated promoter regions. To obtain additional information about the nitrogen regulon and potential cross talks between the nitrogen and the carbon regulon, expression patterns of the whole genome at different nitrogen availabilities and in the presence of different carbon sources will be analyzed by employing DNA-microarrays.