Biochemical and structural investigation of NPM1-mediated liquid-liquid phase separation in Adenovirus infection

概要

Cells that undergo stress or are exposed to sudden environmental changes induce several
morphological, physiological, and metabolic responses to maintain homeostasis. These changes include
reorganization of the cytoplasm and the formation of membrane-less compartments. Liquid phase
separation (LLPS) has recently been reported to mediate the formation of these compartments. Several
groups have reported that cells utilize this process in compartmentalization, activation and inactivation of
biochemical reactions, adaptive response, and even transcriptional control. However, LLPS has also been
implicated in pathological conditions, such as viral infection and disease. Efforts have led to the basic
understanding of the molecules and physical forces driving LLPS. However, the interactions of LLPS
proteins at the atomic level will be pivotal to a better understanding of this process and to the development
of a novel therapy against pathological LLPS.
In this study, LLPS activity of NPM1 was investigated biochemically and structurally to gain
mechanistic insights on this process and further shed light on its biological significance. NPM1 has histone
chaperone, DNA and RNA binding, and ribonuclease activities and plays various roles in cellular
processes, such as ribosome biogenesis and centrosome duplication.
To investigate NPM1's LLPS activity in AdV infection, the structural reorganization of the cell
nucleus during the infection cycle was examined by focusing on the localization of viral DNA replication,
genome packaging, and virus capsid proteins. It was found that viral DNA accumulated in the central
region of the viral DNA replication site. This subnuclear domain was termed as virus-induced postreplication (ViPR) body. Interestingly, NPM1 accumulated in the ViPR body in late-stages of AdV
infection. ...