The adenovirus E4 11 k protein binds and relocalizes the cytoplasmic P-body component Ddx6 to aggresomes

Abstract

The adenovirus E4 11 k protein, product of E4 ORF3, is required in infection for processes including normal accumulation of viral late mRNAs. 11 k restructures both the nucleus and cytoplasm of infected cells by relocalizing specific host cell target proteins, most strikingly components of nuclear PML oncogenic domains. It is likely that in many cases relocalization inactivates target proteins to produce 11 k's effects, although the mechanism and targets for stimulation of late mRNA accumulation is unknown. We have identified a new set of proteins relocalized by 11 k: at least five protein components of cytoplasmic mRNA processing bodies (p-bodies) are found in 11 k-induced cytoplasmic aggresomes, sites where proteins are inactivated or destroyed. One of these p-body proteins, RNA helicase Ddx6, binds 11 k, suggesting a mechanism for relocalization. Because p-bodies are sites for mRNA degradation, their modification by 11 k may provide an explanation for the role of 11 k in viral late mRNA accumulation.