Remodeling of the Human Papillomavirus Type 11 Replication Origin into Discrete Nucleoprotein Particles and Looped Structures by the E2 Protein

Sim, Janet; Özgür, Sezgin; Lin, Biing Yuan; Yu, Jei Hwa; Broker, Thomas R.; Chow, Louise T.; Griffith, Jack D.

doi:10.1016/j.jmb.2007.11.004

Cited by 22 publications

(24 citation statements)

References 38 publications

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“…A recent study has shown that HPV-11 E2 also forms loops with URR fragments containing E2BS, with a frequency similar to that in our results (36). As with BPV-1 and HPV-16, this study found that the full-length protein was necessary for loop formation, and the results suggested that the N-terminal TAD was responsible.…”

Section: Discussionsupporting

confidence: 89%

Dimerization of the Human Papillomavirus Type 16 E2 N Terminus Results in DNA Looping within the Upstream Regulatory Region

Hernandez-Ramon

Burns

Zhang

et al. 2008

J Virol

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Papillomavirus E2 proteins play a central role in regulating viral gene expression and replication. DNAbinding activity is associated with the C-terminal domain of E2, which forms a stable dimer, while the N-terminal domain is responsible for E2's replication and transactivation functions. The crystal structure of the latter domain revealed a second dimerization interface on E2 which may be responsible for DNA loop formation in the regulatory region of the human papillomavirus (HPV) genome. We investigated the biological significance of the N-terminal dimerization by introducing single amino acid substitutions into the dimerization interface. As expected, these substitutions did not influence the C-terminal dimerization and DNA-binding functions of E2. However, the mutations led to reduced transactivation of a synthetic E2-responsive reporter gene, while HPV DNA replication was unaffected. The effect of the mutations on DNA looping was visualized by atomic force microscopy. While wild-type E2 was able to generate DNA loops, all three mutant E2 proteins were defective in this ability. Our results suggest that N-terminal dimerization plays a role in E2-mediated transactivation, probably via DNA looping, a common mechanism for remote regulation of gene transcription.Several members of the human papillomavirus (HPV) family have been strongly implicated in the development of human cancers, particularly cervical cancer; of these, HPV type 16 (HPV-16) is the most common type found in tumors (25). Indeed, the presence of HPV DNA has been identified as the major risk factor for cervical carcinoma and is increasingly implicated in a number of other human tumors (4, 14). The E2 proteins of HPVs are central regulatory proteins in the viral life cycle. While considered to be a typical transcription factor, the E2 protein is equally important in the initiation of viral DNA replication. The loss or deletion of the E2 open reading frame (ORF) occurs frequently in cervical carcinoma cells when the genome of highrisk HPV types, such as HPV-16, becomes integrated into the cell genome (10). This has resulted in a hypothesis which states that the removal of E2 control results in deregulated expression of the HPV oncogenes E6 and E7. The presumed mode of action of HPV E2 is mediated by its binding to the consensus sequence AGGCN 4 GCCT, which is normally present in four copies in the upstream regulatory region (URR) of the genomes of genital HPVs at highly conserved locations relative to the transcriptional start site and origin of viral DNA replication (26). It has been proposed that binding to these sites has a hierarchical priority which at low concentrations of E2 results in transcriptional transactivation, whereas increasing amounts result in repression of the HPV early promoter (18,29,38). However, it has recently been shown that, in the case of HPV-16, E2 binding sites (E2BS) 1 and 2 (and 3 to a certain degree) are important for transcriptional repression, independent of binding affinities (37). Hence, the precise mechanism of...

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Section: Discussionsupporting

confidence: 89%

Dimerization of the Human Papillomavirus Type 16 E2 N Terminus Results in DNA Looping within the Upstream Regulatory Region

Hernandez-Ramon

Burns

Zhang

et al. 2008

J Virol

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“…Finally, both the E1 and E2 proteins are implicated in the higher order structure of the viral ori . While the role of the ori DNA structure in replication and maintenance is unknown, it is likely to be important for both replication and maintenance of the HPV genome (Abbate et al, 2004; Sim et al, 2008; Wilson et al, 2002). Importantly, the binding of polyamides is likely to alter the viral DNA conformation profoundly, including possibly at the ori , due to the well-known biophysical effects of polyamides on DNA such as widening the minor groove, shrinking the major groove, and stiffening the double helix (Dervan and Edelson, 2003).…”

Section: Discussionmentioning

confidence: 99%

HPV episome levels are potently decreased by pyrrole–imidazole polyamides

et al. 2011

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Human papillomavirus (HPV) causes cervical cancer and other hyperproliferative diseases. There currently are no approved antiviral drugs for HPV that directly decrease viral DNA load and that have low toxicity. We report the potent anti-HPV activity of two N-methylpyrrole-imidazole polyamides of the hairpin type, polyamide 1 (PA1) and polyamide 25 (PA25). Both polyamides have potent anti-HPV activity against 3 different genotypes when tested on cells maintaining HPV episomes. The compounds were tested against HPV16 (in W12 cells), HPV18 (in Ker4-18 cells), and HPV31 (tested in HPV31 maintaining cells). From a library of polyamides designed to recognize AT-rich DNA sequences such as those in or near E1 or E2 binding sites of the HPV16 origin of replication (ori), 4 polyamides were identified that possessed apparent IC50s ≤ 150 nM with no evidence of cytotoxicity and we report two highly-active compounds here. Treatment of epithelia engineered in organotypic cultures with these compounds also causes a dose-dependent loss of HPV episomal DNA that correlates with accumulation of compounds in the nucleus. Bromodeoxyuridine (BrdU) incorporation demonstrates that DNA synthesis in organotypic cultures is suppressed upon compound treatment, correlating with a loss of HPV16 and HPV18 episomes. PA1 and PA25 are currently in preclinical development as an antiviral compound for treatment of HPV-related disease, including cervical dysplasia. PA1 and related polyamides offer promise as antiviral agents and the ability to regulate HPV episomal levels in cells for the study of HPV biology. We also report that anti-HPV16 activity for Distamycin A, a natural product related to PA1, is accompanied by significant cellular toxicity.

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“…The ori consists of a cluster of three E2 binding sites (BSs) flanking a series of overlapping E1 BSs. Three E2 dimers bind to the ori to form a toroidal ring, presumably partially denaturing the AT-rich E1 BSs in the negatively supercoiled DNA (Sim et al 2008). E2 interacts with E1 and recruits it to ori.…”

Section: The Functions Of E1 and E2 Proteins In Viral Dna Replicationmentioning

confidence: 99%

Human Papillomavirus Infections: Warts or Cancer?

Chow

Broker

2013

Cold Spring Harbor Perspectives in Biology

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Human papillomaviruses (HPVs) are prevalent pathogens of mucosal and cutaneous epithe-lia. Productive infections of squamous epithelia lead to benign hyperproliferative warts, condylomata, or papillomas. Persistent infections of the anogenital mucosa by high-risk HPV genotypes 16 and 18 and closely related types can infrequently progress to high-grade intraepithelial neoplasias, carcinomas-in-situ, and invasive cancers in women and men. HPV-16 is also associated with a fraction of head and neck cancers. We discuss the interactions of the mucosotropic HPVs with the host regulatory proteins and pathways that lead to benign coexistence and enable HPV DNA amplification or, alternatively, to cancers that no longer support viral production. H uman papillomaviruses (HPVs) are ubiquitous small DNA viruses that comprise a family of more than 150 genotypes. Closely related types show a predilection for particular epithelial tissues and have similar pathogenic properties (de Villiers et al. 2004; Bravo et al. 2010). The mucosotropic HPVs can be sexually transmitted. Infections are frequently asymp-tomatic and are cleared by the immune systems. Active cases are manifested as hyperproliferative lesions but often regress into subclinical persis-tency within a year. Latent infections can reactivate following immunosuppression or upon undergoing repeated cycles of wounding and healing (Fig. 1). A small fraction of persistent infections by the high-risk (HR) HPV genotypes leads to cancers (reviewed by zur Hausen 2009). Worldwide, each year there are about 500,000 new cases of cervical cancer and 275,000 deaths. More than 99% of cervical cancers are caused by high-risk (HR) HPVs, and types 16 and 18 are responsible for about 70% of the cases (Wal-boomers et al. 1999). The HR HPVs are also responsible for a high percentage of cancers of other anogenital sites in men and women. Moreover, HPV-16 is associated with a fraction of the head and neck neoplasias, in particular tonsillar and oro-pharyngeal cancers (reviewed by Syrjänen 2010). In contrast, infections by the low-risk (LR) types 6 and 11 cause 90% of genital warts and essentially all laryngeal papillomas (recurrent respiratory papillomatosis or RRP) (reviewed by Derkay and Wiatrak 2008) but they rarely result in carcinomas. Juvenile-onset RRP results from transmission in utero or during passage through the birth canal of mothers with active condylomata, yet infections may become symptomatic years later. Recent studies

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Remodeling of the Human Papillomavirus Type 11 Replication Origin into Discrete Nucleoprotein Particles and Looped Structures by the E2 Protein

Cited by 22 publications

References 38 publications

Dimerization of the Human Papillomavirus Type 16 E2 N Terminus Results in DNA Looping within the Upstream Regulatory Region

Dimerization of the Human Papillomavirus Type 16 E2 N Terminus Results in DNA Looping within the Upstream Regulatory Region

HPV episome levels are potently decreased by pyrrole–imidazole polyamides

Human Papillomavirus Infections: Warts or Cancer?

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