Adenovirus
protein VIII appears to connect core with the inner surface of the adenovirus capsid. Because
protein-
protein interactions are central to virus replication, identification of
proteins interacting with
protein VIII may help in understanding their role in
adenovirus infection. Our yeast 2-hybrid assay indicated that
protein VIII interacts with
eukaryotic initiation factor 6 (eIF6). These findings were confirmed by
Glutathione S-transferase-pull down assay, bimolecular fluorescent complementation assay, and coimmunoprecipitation assay in plasmid
DNA transfected and bovine adenovirus-3 (BAdV-3) infected cells. The C-terminus
amino acids 147 to 174 of
protein VIII and N-terminus
amino acids 44 to 97 of eIF6 are involved in these interactions. Polysome analysis demonstrated increased level of 60S ribosomal subunit and decreased level of 80S complex in
protein VIII expressing cells or BAdV-3 infected cells. Our results suggest that formation of functional 80S ribosome appears impaired in the presence of
protein VIII at late times post
infection. We speculate that this impaired ribosome assembly may be responsible for the inhibition of cellular mRNA translation observed late in adenovirus infected cells. Moreover, analysis of recombinant BAdV-3 expressing
mutant protein VIII (deletion of eIF6 interacting domain) suggests that interaction of
protein VIII and eIF6 may help in preferential translation of adenovirus genes during late phase of
adenovirus infection.