Structure and function of the archaeal transcription factor C34/TFEbeta: The structural and functional characterisation of an archaeal homologue of the general transcription factor TFIIEbeta and the RNA polymerase III subunit C34 will provide insight into

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A major event in the early evolution of cellular life on Earth has been its branching into three domains with fundamental differences concerning the structural and functional organization of cells: Bacteria, Archaea and Eukaryotes (yeast, plants, animals etc.). In all cellular life, RNA polymerases are protein complexes responsible for the first step in gene expression, the transcription of DNA to RNA. In Eukaryotes, different types of RNA polymerases transcribe different classes of genes. Each of the different types of RNA polymerases is recruited to its target genes by a specific set of transcription inititiation factor proteins. Archaea and Bacteria use a single RNA polymerase for all genes. Notably, the archaeal RNA polymerase and its general transcription factors resemble the eukaryotic RNA polymerases II and III with their basic sets of general transcription factors. Studies on transcription in Archaea have therefore provided fundamental insight on the process of transcription and how it remained conserved during the course of evolution. I have recently identified the archaeal protein that forms the counterpart to eukaryotic TFIIEbeta and C34, two related proteins with functions in transcription initiation of eukaryotic RNA polymerases II and III, respectively. The archaeal C34/TFEbeta represents a „missing link“ in the evolutionary history of archaeal and eukaryotic transcription machineries. The proposed project investigates the biological function of archaeal C34/TFEbeta, especially its role in transcription initiation. In addition, I will determine the interaction network that the archaeal C34/TFEbeta protein forms with other components of the transcription apparatus. The overall goal is to reveal structural and functional homologies between the archaeal C34/TFEbeta protein and its eukaryotic counterparts. The proposed project will advance our understanding of the early evolution of RNA polymerases and transcription systems in Archaea and Eukaryotes.