Authors: H G P van Gennip A T Hesselink R J M Moormann M M Hulst
Publish Date: 2005/06/28
Volume: 150, Issue: 11, Pages: 2271-2286
Abstract
The pestivirus glycoprotein Erns a ribonuclease is expressed on the surface of virions and in infected cells as a disulfidelinked homodimer Erns is involved in the infection process and its RNase activity is probably involved in viral replication and pathogenesis The most Cterminal cysteine residue forms an intermolecular disulfide bond with another Erns monomer resulting in an Erns dimer To study the function of dimerisation of Erns for viral replication the cysteine residue at amino acid position 438 was mutated into a serine residue The mutated C438S gene was cloned into a vector containing an infectious cDNA copy of the CSFV Cstrain genome Using reverse genetics a mutant virus was generated that only expressed monomeric Erns confirming that Cys 438 is essential for homodimerisation Characterization of this mutant virus and of a baculovirusexpressed C438S mutant protein indicated that the loss of the dimeric state of Erns reduced the affinity of binding of virions and Erns to heparan sulphate HS the receptor for Erns on the cell surface of SK6 cells This suggests that interaction of virusbound Erns homodimers with membrane associated HS may be a joined action of the two HSbinding domains one in each monomer present in the homodimer
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