The Zygosaccharomyces bailii antifungal virus toxin zygocin: cloning and expression in a heterologous fungal host

摘要: Zygocin, a monomeric protein toxin secreted by virus-infected killer strain of the osmotolerant spoilage yeast Zygosaccharomyces bailii, kills broad spectrum human and phytopathogenic yeasts filamentous fungi disrupting cytoplasmic membrane function. The is encoded double-stranded (ds)RNA virus (ZbV-M, for Z. bailii M) that stably persists within cell cytosol. In this study, was purified, its N-terminal amino acid sequence determined, full-length cDNA copy 2.1 kb viral dsRNA genome cloned successfully expressed in heterologous fungal system. Sequence analysis as well zygocin expression Schizosaccharomyces pombe indicated vivo 238-amino-acid preprotoxin precursor (pptox) consisting hydrophobic secretion signal, followed potentially N-glycosylated pro-region terminating classical Kex2p endopeptidase cleavage site generates N-terminus mature biologically active late Golgi compartment. Matrix-assisted laser desorption mass spectrometry further 10.4 kDa lacking detectable post-translational modifications. Furthermore, we present additional evidence contrast with other antifungal toxins, immunity not mediated itself and, therefore, pptox zygocin-sensitive host results suicidal phenotype. Final comparisons emphasize conserved pattern functional elements viruses naturally infect phylogenetically distant hosts (Saccharomyces cerevisiae bailii) reinforce models are required RNA packaging replication.