Mapping of herpes simplex virus-1 VP22 functional domains for inter- and subcellular protein targeting

The herpes simplex virus 1 (HSV-1) tegument protein VP22 has been utilised as a vehicle for trafficking proteins. It has a remarkable property of exit ing the cell that is producing it and entering the neighbouring cells, whic h has been used to deliver therapeutic proteins, p53 and herpes simplex vir us thymidine kinase (tk). It has a complex pattern of expression and subcel lular localisation. Functions of VP22 include intercellular transport, bind ing to and bundling of microfilaments, inducing cytoskeleton collapse, nucl ear translocation during mitosis, and binding to chromatin and nuclear memb rane. The regions of VP22 which contain each of these functions have not be en characterised. Finding the region carrying the property of intercellular spread would facilitate enhancement of transport function. By constructing a series of deletion constructs of VP22 tagged by the green fluorescent pr otein (GFP) we have mapped the functions of VP22 to specific regions in the polypeptide as follows: intercellular transport aa 81-195, binding and reo rganisation of cytoskeleton - aa 159-267; nuclear targeting, inhibition of cytoskeleton collapse - aa 81-121; and nuclear targeting and facilitation o f intercellular transport - aa 267-301. Separation of VP22 functions enable s focus on the mechanism of VP22-mediated transport and improve the transpo rtation efficiency of VP22.