Browsing by Subject "papillomavirus"

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Conserved Residues in Murine Papillomavirus E2 Regulate the Viral Life Cycle
    (2024-12) Gonzalez, Jessica Kay; Androphy, Elliot J.; Dong, X. Charlie; Katzenellenbogen, Rachel; Robinson, Christopher
    Papillomaviruses (PVs) are small, non-enveloped DNA viruses that infect the stratified epithelia. Once an infection is initiated, the virus must successfully navigate the three stages of its life cycle: establishment, maintenance, and vegetative amplification. A major mechanism of regulating this viral program is post-translational modification on the viral E2 protein, which is responsible for orchestrating viral transcription, replication, and genome partitioning. The hypothesis underscoring this work is that residues in E2 are highly conserved across PV types because they serve some structural or functional purpose for the virus. A targeted mutant library was generated in E2 from murine papillomavirus (MmuPV1) to investigate conserved residues that have been shown to be post-translationally modified in the E2 of other PVs, including BPV-1 and high-risk HPV-31. In the transactivation domain (TAD) tyrosine 102 and the lysine 112/113 motif were modified to their constitutively modified (phosphorylated and acetylated, respectively) or unmodified states, while cysteine 307 in the DNA binding and dimerization domain (DBD) was mutated to a less-reactive serine or DNA binding defective phenylalanine mutant. We characterized how mutation at each of these conserved sites alters E2 function using a battery of in vitro assays to assess for transcription and replication ability. We also studied how each mutant contributes to disease progression using an immunocompromised mouse model assessing cutaneous disease. We demonstrate that mutants which fail to replicate transiently in vitro will also fail to induce proliferative wart formation, establishing a predictive link between in vitro and in vivo experiments. Taken together, our findings suggest that modifications on conserved residues in E2 act as molecular switches that regulate E2 activity throughout the cellular and viral life cycle.
  • Thumbnail Image
    Item
    The SMC5/6 Complex Represses the Replicative Program of High-Risk Human Papillomavirus Type 31
    (MDPI, 2020-09) Gibson, Ryan T.; Androphy, Elliot J.; Microbiology and Immunology, School of Medicine
    The multi-subunit structural maintenance of chromosomes (SMC) 5/6 complex includes SMC6 and non-SMC element (NSE)3. SMC5/6 is essential for homologous recombination DNA repair and functions as an antiviral factor during hepatitis B (HBV) and herpes simplex-1 (HSV-1) viral infections. Intriguingly, SMC5/6 has been found to associate with high-risk human papillomavirus (HPV) E2 regulatory proteins, but the functions of this interaction and its role during HPV infection remain unclear. Here, we further characterize SMC5/6 interactions with HPV-31 E2 and its role in the HPV life cycle. Co-immunoprecipitation (co-IP) revealed that SMC6 interactions with HPV-31 E2 require the E2 transactivation domain, implying that SMC5/6 interacts with full-length E2. Using chromatin immunoprecipitation, we found that SMC6 is present on HPV-31 episomes at E2 binding sites. The depletion of SMC6 and NSE3 increased viral replication and transcription in keratinocytes maintaining episomal HPV-31, indicating that SMC5/6 restricts the viral replicative program. SMC6 interactions with E2 were reduced in the presence of HPV-31 E1, suggesting that SMC6 and E1 compete for E2 binding. Our findings demonstrate SMC5/6 functions as a repressor of the viral replicative program and this may involve inhibiting the initiation of viral replication.