Identification of functional domains required for HearNPV P10 filament formation

Baculovirus encoded P10 form fibrillar structures in infected cells. We have tried to identify the functional domains for the P10 filament formation by green fluorescence protein (GFP) tag. The p10 gene of Helicoverpa armigera single nucleocapsid nucleopolyhedrovirus (HearNPV) was the subject of these studies. Different lengths of HearNPV p10 gene were constructed with GFP fused in frame to the C-terminus. The constructs were transfected into insect and mammalian cells and observed by confocal microscopy. The results indicated that the first N-terminal 66 amino acids, which form the complete coiled-coil domain, were necessary for the aggregation and formation of filament structures of HearNPV P10. The proline-rich region and the C-terminal positively charged amino acids were not necessary for the formation of fibrillar structure but had some impact on the shape of the fibrillar structures. No other baculoviral proteins were needed for the formation of P10 filament structures in transfected cells.