A Capsid-Encoded PPxY-Motif Facilitates Adenovirus Entry

Wodrich, Harald; Henaff, Daniel; Jammart, Baptist; Segura-Morales, Carolina; Seelmeir, Sigrid; Coux, Olivier; Ruzsics, Zsolt; Wiethoff, Christopher M.; Kremer, Eric J.

In this study we address the mechanisms of Ad cell entry. We demonstrate that the internal capsid protein VI is rapidly exposed to antibodies during cell entry, possibly at the cell surface or immediately after endocytosis. We further determine that protein VI remains partially associated with Ad capsids as they traffic to MTOCs and the NPC. We identify a functional PPxY motif within protein VI that mediates the association of protein VI with Nedd4 E3 ubiquitin ligases and facilitates its ubiquitylation. Recombinant Ad5 in which the protein VI PPxY motif is mutated have normal capsid morphology, escape from endosomes with similar efficiency as wildtype viruses, but are defective in genome delivery to the nucleus. We show that the PPxY motif in protein VI is involved in its efficient microtubule-mediated transport and mutating it in the virus alters the intracellular targeting of Ads towards the MTOC region concomitant with a post-entry block in viral infectivity. Furthermore, Nedd4.1 and Nedd4.2 are involved in Ad infection and intracellular targeting of incoming virions to the MTOC. We propose that the PPxY motif, in other viral systems, may also function during entry and interact with novel cellular pathways for efficient viral entry.