Delineation of a sequence required for nuclear localization of the protein encoded by varicella-zoster virus gene 61

All characterized alphaherpesviruses encode a protein whose N-terminal region contains a novel zinc-binding motif, the C3HC4 domain. Homology between the different proteins is in general limited to key residues in this domain. In order to identify a separate landmark site in the C3HC4 protein encoded by varicella-zoster virus gene 61, namely the region required for nuclear localization, we have analysed a range of mutants in transient expression and immunofluorescence experiments. A basic region (RGAKRR) at residues 387 to 392 was found to be required for nuclear localization, and residues 390 and 391 were critical.