Sumoylation at the Host-Pathogen Interface

Wilson, Van G.

Similar to the ORF61 story, the herpes simplex virus (HSV) ICP0 protein has several putative SIM-like sequences (SLSs), and SLS-4, -5, and -7 contribute to SUMO binding, to degradation of SUMO modified PML isoforms, and to the biological ability of ICP0 to overcome intrinsic anti-viral defenses [67] . Early in infection, unknown SUMO conjugates, along with PML, are recruited to viral genomes that can be visualized as punctate foci in the nucleus. ICP0 is subsequently recruited to these foci in a SUMO2/3-dependent fashion, suggesting that recruitment depends on SIM-SUMO interactions. This ICP0 recruitment does not require PML, so presumably the unknown sumoylated proteins that accumulate with the viral genomes are sufficient to direct ICP0. As for the ORF61 protein, it appears that SUMO moieties are critical signals that mediate localization of ICP0 to the viral genomes in order to counteract the repressive effect of PML and NB proteins. While a number of other viral proteins also disrupt NBs, the role of SIM motifs for targeting these proteins has not been reported; further discussion of NB disruption can be found in section 4.4.