Conserved E1B-55K SUMOylation in Different Human Adenovirus Species Is a Potent Regulator of Intracellular Localization

Over the past decades, studies on the biology of human adenovi-ruses (HAdVs) mainly focused on the HAdV prototype species C type 5 (HAdV-C5) and revealed fundamental molecular insights into mechanisms of viral replication and viral cell transformation. Recently, other HAdV species are gaining more and more attention in the field. Reports on large E1 B proteins (E1 B-55K) from different HAdV species showed that these multifactorial proteins possess strikingly differ-ent features along with highly conserved functions. In this work, we identified potential SUMO-conjugation motifs (SCMs) in E1 B-55K proteins from HAdV spe-cies A to F. Mutational inactivation of these SCMs demonstrated that HAdV E1 B-55K proteins are SUMOylated at a single lysine residue that is highly conserved among HAdV species B to E. Moreover, we provide evidence that E1B-55K SUMOylation is a potent regulator of intracellular localization and p53-mediated transcription in most HAdV species. We also identified a lysine residue at position 101 (K101), which is unique to HAdV-C5 E1B-55K and specifically regulates its SUMOylation and nucleo-cytoplasmic shuttling. Our findings reveal important new aspects on HAdV E1B-55K proteins and suggest that different E1 B-55K spe-cies possess conserved SCMs while their SUMOylation has divergent cellular effects during infection. IMPORTANCE E1B-55K is a multifunctional adenoviral protein and its functions are highly regulated by SUMOylation. Although functional consequences of SUMOylated HAdV-C5 E1B-55K are well studied, we lack information on the effects of SUMOylation on homologous E1B-55K proteins from other HAdV species. Here, we show that SUMOylation is a conserved posttranslational modification in most of the E1B-55K pro-teins, similar to what we know about HAdV-C5 E1B-55K. Moreover, we identify subcel-lular localization and regulation of p53-dependent transcription as highly conserved SUMOylation-regulated E1B-55K functions. Thus, our results highlight how HAdV pro-teins might have evolved in different HAdV species with conserved domains involved in virus replication and differing alternative functions and interactions with the host cell machinery. Future research will link these differences and similarities to the diverse pathogenicity and organ tropism of the different HAdV species.

Automated summary

This research identified potential SUMO-conjugation motifs in E1B-55K proteins from HAdV species A to F and demonstrated that these proteins are SUMOylated at a highly conserved lysine residue. The study also revealed that E1B-55K SUMOylation regulates intracellular localization and p53-mediated transcription in most HAdV species.