| 摘要: | Pseudorabies virus (PrV) belongs to the α-herpesvirinae of which human simplex virus (HSV) is the prototype virus.One of the hallmarks of HSV infection is shutoff of protein synthesis that is mediated by various viral proteins includingvhs (virion host shutoff), which is encoded by the UL41 gene. However, the function of PrV vhs is poorly understood.Due to the low sequence similarity (39.3%) between the HSV and PrV UL41 proteins, vhs might not share thesame biochemistry characteristics. The purpose of this study was to characterize the nuclease activity of the PrV vhsprotein with respect to substrate specificity, its requirements in terms of cofactors, and the protein regions, as wellas key amino acids, which contribute to vhs activity. Our results indicated that, similar to HSV vhs, PrV vhs is able todegrade ssRNA and mRNA. However, PrV vhs also targeted rRNA for degradation, which is novel compared to theHSV-1 vhs. Activity assays indicated that Mg2+ alone enhances RNA degradation mediated by PrV vhs, while K+ andATP are not sufficient to induce activity. Finally, we demonstrated that each of the four highly conserved functionalboxes of PrV vhs contributes to RNA degradation and that, in particular, residues 152, 169, 171, 172, 173 343, 345, 352and 356, which are conserved among α-herpesviruses, are key amino acids needed for PrV vhs ribonuclease activity. |
