Charakterisierung der Proteaseaktivität und Spezifität der OTU-Domäne (ovarian tumour domain) des L-Proteins des Krim-Kongo-Fieber-Virus

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Ubiquitin processing enzymes play an important role in host-pathogen interactions and some pathogen genomes encode for deubiquitinating enzymes (DUBs). Ovarian tumour (OTU) domain containing proteins were recently identified to harbour DUB activity and are conserved throughout evolution. Crimean-Congo hemorrhagic fever virus large protein (CCHFV-L) contains a predicted OTU domain, providing an entry point to further examine the functions of this complex viral protein. In this study, subunits of CCHFV-L protein containing the OTU domain and additional motifs possibly participating in protease function will be analysed for their potential to cleave ubiquitin from different substrates. Purified proteins expressed in prokaryotic cells from synthetic open reading frames will give first hints on their protease activity in vitro. Small active site modifiers specific for DUBs will be used to identify the active site cysteine and further characterise protease activity and specificity in eukaryotic cells. Inactive protease mutants trapping ubiquitinated cellular or viral substrate proteins within the active site will allow identification of CCHFV-L target proteins and provide insight into cellular mechanisms impaired by viral infection. The discovery of novel mechanisms of the CCHFV-L protein to exploit cellular functions will shed light on the biological role of this viral component during infection, and provide a window for potential antiviral pharmaceutical intervention.