Epstein-Barr virus immediate-early protein BZLF1 is SUMO-1 modified and disrupts promyelocytic leukemia bodies

Although the immediate-early proteins of both herpes simplex virus (HSV) an d cytomegalovirus (CMV) are known to modify promyelocytic leukemia (PML) (N D10) bodies in the nucleus of the host cell, it has been unclear whether ly tic infection with gamma herpesviruses induces a similar effect. The PML pr otein is induced by interferon, involved in major histocompatibility comple x class I presentation, and necessary for certain types of apoptosis. There fore, it is likely that PML bodies function in an antiviral capacity. SUMO- 1 modification of PML is known to be required for the formation of PML bodi es, To examine whether Epstein-Barr virus (EBV) lytic replication interfere s with PML bodies, we expressed the EBV immediate-early genes BZLF1 (Z) and BRLF1 (R) in EBV-positive cell lines and examined PML localization. Both Z and R expression resulted in PML dispersion in EBV-positive cells. Z but n ot R expression is sufficient to disrupt PML bodies in EBV-negative cell li nes. We show that dispersion of PML bodies by Z requires a portion of the t ranscriptional activation domain of Z but not the DNA-binding function. As was previously reported for the HSV-1 ICP0 and CMV IE1 proteins, Z reduces the amount of SUMO-l-modified PML. We also found that Z itself is SUMO-1 mo dified (through amino acid 12) and that Z competes with PML for limiting am ounts of SUMO-1. These results suggest that disruption of PML bodies is imp ortant for efficient lytic replication of EBV. Furthermore, Z may potential ly alter the function of a variety of cellular proteins by inhibiting SUMO- 1 modification.