Understanding of gene regulation in halophilic Archaea: Characterization of the transcriptome, DNA protein interactions, and posttranslational control

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Informational proteins of Archaea in e.g. replication, transcription and translation, are homologous to eukaryotic proteins. In contrast, many metabolic proteins of Archaea are closer related to bacterial proteins. The regulation of "bacterial-like" genes in organisms with an "eukaryotic-like" transcriptional apparatus is not understood. Halobacterium salinarum is an excellent model system to study archaeal gene regulation, because it is metabolically very versatile and can grow aerobically, microaerobically, phototrophically, fermentatively and by anaerobic respiration. It is able to perceive a variety of chemical and physical environmental signals. Furthermore, the genome sequence is available, functional genomic studies have been initiated and molecular and biochemical techniques are far developed. In the proposed project DNA microarrays will be used to characterize differential expression of all genes of wildtype cells and of specifically constructed mutants in response to different environmental changes and to cell density-generated signals. This will allow to identify regulatory hierachies and circuits. The binding sites of selected gene-specific and of global regulators will be characterized in vitro and in vivo. The interaction of selected regulatory proteins with basal transcription factors and with DNA will be quantitavely characterized on the molecular level.