As with many proteins multimers studied in biophysics, the assembly and disassembly dynamical pathways of hepatitis B virus (HBV) capsid proteins are not symmetrical. Using time-resolved small-angle X-ray scattering and singular value decomposition analysis, we have investigated these processes in vitro by a rapid change of salinity or chaotropicity. Along the assembly pathway, the classical nucleation-growth mechanism is followed by a slow relaxation phase during which capsid-like transient species selforganize in accordance with the theoretical prediction that the capture of the few last subunits is slow. By contrast, the disassembly proceeds through unexpected, fractalbranched clusters of subunits that eventually vanish over a much longer timescale. On the one hand, our findings confirm and extend previous views as to the hysteresis phenomena observed and theorized in capsid formation and dissociation. On the other hand, they uncover specifics that may directly relate to the functions of HBV subunits in the viral cycle.

Parisotto et al. demonstrate that ablation of the tumor suppressor gene PTEN in prostatic luminal epithelial cells of adult mice stimulates their proliferation, induces replication stress and a DNA damage response, followed by growth arrest with characteristics of cell senescence.