Biochemistry & Biophysics | Immunology & Pathogens
Interactions between viruses and cells
Most viruses interfere with or modulate host systems to ensure successful replication. My group has been looking at the interactions between the leader proteinase of foot-and-mouth disease virus and the 2A proteinase of the common...more
Most viruses interfere with or modulate host systems to ensure successful replication. My group has been looking at the interactions between the leader proteinase of foot-and-mouth disease virus and the 2A proteinase of the common cold virus and coxsackieviruses with the cellular protein called eukaryotic initiation factor 4G (eIF4G). This protein is involved in recruiting capped cellular mRNA to the ribosomes for protein synthesis. Cleavage of this molecule during replication of the above mentioned viruses thus prevents capped cellular mRNA being translated. Viral protein synthesis is unaffected as it initiates internally downstream of the 5’ end of its RNA.
We have determined the molecular structures of three of these proteinases and investigated the sites at which they interact with eIF4G. The leader proteinase is a relative of the plant cysteine proteinase papain. However, in contrast to papain, the leader proteinase is very specific, with only three target proteins identified at present. Nevertheless, a consensus sequence representing the cleavage site has been difficult to define as the three known cleavage sites show considerable differences (Santos et al, 2009). We have recently started to use our knowledge of the cleavage sites to develop specific inhibitors of the enzyme. For the 2A proteinase, our recent work is concentrating on obtaining a crystal structure of the poliovirus enzyme. This may allow inhibitors to be designed that can be used in the poliovirus eradication campaign of the WHO.
Recently, in collaboration with Christian Mandl and Franz Heinz (Medical University of Vienna), we have started to examine how the tick-borne encephalitis virus (TBEV) and West Nile virus (WNV) proteins are synthesised in an infected cell. Specifically, we have replaced one of the viral proteinase cleavage sites with a sequence from foot-and-mouth disease virus that can split the polypeptide chain without viral proteinase activity. Both TBEV and WNV containing with this sequence were viable. However, whereas the TBEV mutant grew only in mammalian cells but not tick cells, the WNV mutant was unstable in mammalian cells but grew well in mosquito cells (Schrauf et al, 2009). This system reveals that different flaviviruses have different requirements in their cognate host cells and will be useful in elucidating the nature of the differences, especially in studying the interactions of the viral proteins with structures found in the host cells.
Video: A film by Amelie Schoenenwald and Chiara Masnovo (University of Vienna). A WTZ Ost production (2017) in cooperation with Okto Community TV supported by Austria Wirtschaftsservice and the Federal Ministry of Science, Research and Economy.
Fedosyuk, Sofiya; Bezerra, Gustavo Arruda; Radakovics, Katharina; Smith, Terry K; Sammito, Massimo; Bobik, Nina; Round, Adam; Ten Eyck, Lynn F; Djinovic-Carugo, Kristina; Usón, Isabel; Skern, Tim (2016). Vaccinia Virus Immunomodulator A46: A Lipid and Protein-Binding Scaffold for Sequestering Host TIR-Domain Proteins. PLOS PATHOG;12(12):e1006079. PMID: 27973613
Aumayr, Martina; Fedosyuk, Sofiya; Ruzicska, Katharina; Sousa-Blin, Carla; Kontaxis, Georg; Skern, Tim (2015). NMR analysis of the interaction of picornaviral proteinases Lb and 2A with their substrate eukaryotic initiation factor 4GII. PROTEIN SCI;24(12):19791996. PMID: 26384734
Fedosyuk, Sofiya; Grishkovskaya, Irina; De Almeida Ribeiro, Euripedes; Skern, Tim (2014). Characterisation and structure of the vaccinia virus NF-κB antagonist A46. J BIOL CHEM;289(6):3749-62. PMID: 24356965
Doctoral Program "Integrative Structural Biology"
2016-2019: The Group Skern participates in the special Doctoral Program "Integrative Structural Biology" reviewed and funded by the Austrian Science Fund FWF. Tim Skern is the Speaker of the program.
FWF Stand Alone Project
"Substraterkennung durch picornavirale Proteasen L und 2A"
Project number P 28183
Doctoral Program "Structure and Interaction of Biological Macromolecules"
2009-2013: Tim Skern was the speaker of the Doctoral Program "Structure and Interaction of Biological Macromolecules" reviewed and funded by the Austrian Science Fund FWF, the University of Vienna and the Medical University of Vienna.