We have examined the subcellular localization properties of human adenovirus 2 (HAdV-2) preMu and mature Mu (pX) proteins as fusions with enhanced green fluorescence protein (EGFP). We determined that preMu is exclusively a nucleolar protein with a single nucleolar accumulation signal within the Mu sequence. In addition, we noted that both preMu-EGFP and Mu-EGFP are excluded from adenovirus DNA-binding protein (DBP)-rich replication centres in adenovirus-infected cells. Surprisingly, we observed that cells in which preMu-EGFP (but not Mu-EGFP) is transiently expressed prior to or shortly after infection with Ad2 did not express late adenovirus genes. Further investigation suggested this might be due to a failure to express pre-terminal protein (preTP) from the E2 region, despite expression of another E2 protein, DBP. Deletion mutagenesis identified a highly conserved region in the C terminus of preMu responsible for these observations. Thus our data suggest that preMu may play a role in modulating accumulation of proteins from the E2 region.
Lee, T. W. R., Lawrence, F., Dauksaite, V., Akusjärvi, G., Blair, G. E., & Matthews, D. A. (2004). Precursor of human adenovirus core polypeptide Mu targets the nucleolus and modulates the expression of E2 proteins. Journal of General Virology, 85(1), 185-196. https://doi.org/10.1099/vir.0.19352-0