Indiana University-Purdue University Indianapolis (IUPUI) / Papillomaviruses (PVs) are non-enveloped DNA viruses that are the primary
etiological agents of cervical and oropharyngeal cancers. Vaccines for
H(human)PV have proven to be effective prophylactic treatments; however, there
is no treatment available for those currently infected. To develop new therapies,
we require a clear understanding of viral pathogenesis and regulation.
The Papillomavirus E2 protein is a sequence specific DNA binding protein that
recruits cellular factors to its genome in infected epithelial cells. E2 also binds to
and loads the viral E1 DNA helicase at the origin of replication. Post-translational
modifications of PV E2 have been identified as potential regulators of E2
functions. We recently reported lysine (K) 111 as a target of p300 acetylation in
B(bovine)PV that is involved in the regulation of viral transcription. K111 is
conserved in most papillomaviruses, so we pursued a mutational approach to
query the functional significance of lysine in HPV E2. Amino acid substitutions
that prevent acetylation, including arginine, were unable to stimulate transcription
and E1 mediated DNA replication. The arginine K111 mutant retained E2
transcriptional repression, nuclear localization, DNA and chromatin binding, and
association with E2 binding partners involved in PV transcription and replication. When directly investigating origin unwinding, the replication defective E2 K111R
mutant recruited E1 to the viral replication origin, but surprisingly, unwinding of
the duplex DNA did not occur. In contrast, the glutamine K111 mutant increased
origin melting and stimulated replication compared to wild type E2. We have
identified Topoisomerase I as a key host factor involved in viral replication whose
recruitment is dependent on K111 acetylation, and propose a new model for viral
origin dynamics during replication initiation. This work reveals a novel activity of
E2 necessary for denaturing the viral origin that likely depends on acetylation of highly conserved lysine 111.
| Identifer | oai:union.ndltd.org:IUPUI/oai:scholarworks.iupui.edu:1805/14601 |
| Date | 26 June 2017 |
| Creators | Thomas, Yanique Serge Gillana |
| Contributors | Androphy, Elliot J., Klemsz, Michael, Yu, Andy, Mayo, Lindsey, Lee, Suk-Hee |
| Source Sets | Indiana University-Purdue University Indianapolis |
| Language | en_US |
| Detected Language | English |
| Type | Dissertation |
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