Browsing by Subject "MmuPV1"

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    A Conserved Di-Lysine Motif in the E2 Transactivation Domain Regulates MmuPV1 Replication and Disease Progression
    (MDPI, 2025-01-16) Gonzalez, Jessica; DeSmet, Marsha; Androphy, Elliot J.; Microbiology and Immunology, School of Medicine
    The papillomavirus E2 protein regulates the transcription, replication, and segregation of viral episomes within the host cell. A multitude of post-translational modifications have been identified which control E2 functions. A highly conserved di-lysine motif within the transactivation domain (TAD) has been shown to regulate the normal functions of the E2 proteins of BPV-1, SfPV1, HPV-16, and HPV-31. This motif is similarly conserved in the E2 of the murine papillomavirus, MmuPV1. Using site-directed mutagenesis, we show that the first lysine (K) residue within the motif, K112, is absolutely required for E2-mediated transcription and transient replication in vitro. Furthermore, mutation of the second lysine residue, K113, to the potential acetyl-lysine mimic glutamine (Q) abrogated E2 transcription and decreased transient replication in vitro, while the acetylation defective arginine (R) mutant remained functional. Both K113 mutants were able to induce wart formation in vivo, though disease progression appeared to be delayed in the K113Q group. These findings suggest that acetylation of K113 may act as a mechanism for repressing MmuPV1 E2 activity.
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    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.