CONICET | Buscador de Institutos y Recursos Humanos

CCT, also known as TCP-1 Ring Complex or TRiC, is an essential and conserved chaperonin complex that interacts with a large number of cellular targets, assisting in their folding in an ATP-dependent manner. It is formed by two rings, of eight different but related subunits, each represented once per eight-membered ring.The Human Papillomavirus (HPV) capsid is composed of the two structural proteins L1 and L2, with the L2 protein playing a crucial role in trafficking the viral DNA (vDNA) to the nucleus. Proteomic studies done using mammalian cells expressing HPV-16 L2 led to the identification of CCT proteins as probable novel interaction partners. Consequently, in this study we analyze the interaction of HPV structural proteins with different components of the CCT complex and the relevance of this interaction during infection. We found that the CCT3 subunit binds to L2, and we mapped this interaction to the N-terminal region of the viral protein. Moreover, it was observed that loss of CCT3 in mammalian cells causes a reduction in the levels of HPV infection. Interestingly, by confocal immunofluorescence, HPV pseudoviral particles (PsVs) were found to colocalize with CCT3 at early times after infection and this colocalization occurring in Rab7-positive structures.Furthermore, CCT was also found to be important for HPV assembly. By producing PsVs in CCT3-silenced cells, we observed that viral production in the absence of the mentioned chaperonin component led to fewer infectious particles. Even when the total amount and ratios of the structural proteins are unaltered, PsVs generated in cells lacking CCT3 were found to be less stable. Moreover, a defect in the total amount of vDNA encapsidated was also observed.In conclusion, these results indicate that the CCT complex plays an important role both during virus infection and in virus assembly.