High ionic strength buffer or the addition of protocatechuic acid (PCA) enhances the integration of full-length prototype foamy virus intasomes by preventing aggregation.
The disordered outer CTDs of PFV intasomes contribute to aggregation, which can be prevented by high ionic strength buffer or the small molecule protocatechuic acid, enhancing intasome stability and integration activity in vitro.
The integrase (IN) enzyme of retrovirus prototype foamy virus (PFV) consists of four domains: amino terminal extension (NED), amino terminus (NTD), catalytic core (CCD), and carboxyl terminus domains (CTD). A tetramer of PFV IN with two viral DNA ends forms the functional intasome. Two inner monomers are catalytically active while the CCDs of the two outer monomers appear to play only structural roles. The NED, NTD, and CTD of the outer monomers are disordered in intasome structures. Truncation mutants reveal that integration to a supercoiled plasmid increases without the outer monomer CTDs present. Deletion of the outer CTDs enhances the lifetime of the intasome compared to full length (FL) IN or deletion of the outer monomer NTDs. High ionic strength buffer or several additives, particularly protocatechuic acid (PCA), enhance the integration of FL intasomes by preventing aggregation. These data confirm previous studies suggesting the disordered outer domains of PFV intasomes are not required for intasome assembly or integration. Instead, the outer CTDs contribute to aggregation of PFV intasomes which may be inhibited by high ionic strength buffer or the small molecule PCA.
Jones et al. (2019) studied Prototype foamy virus (PFV) integration. Protocatechuic acid (PCA) and outer domain truncations vs. Full length integrase without PCA was evaluated on Intasome aggregation and concerted integration activity. High ionic strength buffer or the addition of protocatechuic acid (PCA) enhances the integration of full-length prototype foamy virus intasomes by preventing aggregation.