In vivo analysis of the cell cycle dependent association of the bovine papillomavirus E2 protein and ChlR1

Feeney, Katherine M; Saade, Anastasia; Okrasa, Krzysztof; Parish, Joanna L

doi:10.1016/j.virol.2011.03.015

Cited by 16 publications

(24 citation statements)

References 41 publications

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“…TopBP1 and TopBP1; it could also be due to the natural stickiness of E2 to beads used in these coimmunoprecipitation experiments (14,18). What is clear from this experiment is that E2…”

Section: Resultsmentioning

confidence: 97%

“…Lanes 6 to 10 dem- WT interacts well with endogenous TopBP1, whereas mutant 8 is severely compromised, as shown in lane 5. The shadow band observed may indicate some residual binding, but there may also be a contribution to this from the "stickiness" of E2 for the beads (14,18 WT with no squelching at higher levels, and there is a significant difference between E2 TopBP1 and E2 WT activity at 10 ng of input plasmid. These results demonstrate that E2 TopBP1 is folded correctly and can bind to target DNA sequences and that there are differences between the transcriptional activation properties of this mutant and E2…”

Section: Resultsmentioning

confidence: 99%

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An Interaction between Human Papillomavirus 16 E2 and TopBP1 Is Required for Optimum Viral DNA Replication and Episomal Genome Establishment

Donaldson

Mackintosh

Bodily

et al. 2012

J Virol

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bIn human papillomavirus DNA replication, the viral protein E2 forms homodimers and binds to 12-bp palindromic DNA sequences surrounding the origin of DNA replication. Via a protein-protein interaction, it then recruits the viral helicase E1 to an A/T-rich origin of replication, whereupon a dihexamer forms, resulting in DNA replication initiation. In order to carry out DNA replication, the viral proteins must interact with host factors that are currently not all known. An attractive cellular candidate for regulating viral replication is TopBP1, a known interactor of the E2 protein. In mammalian DNA replication, TopBP1 loads DNA polymerases onto the replicative helicase after the G 1 -to-S transition, and this process is tightly cell cycle controlled. The direct interaction between E2 and TopBP1 would allow E2 to bypass this cell cycle control, resulting in DNA replication more than once per cell cycle, which is a requirement for the viral life cycle. We report here the generation of an HPV16 E2 mutant compromised in TopBP1 interaction in vivo and demonstrate that this mutant retains transcriptional activation and repression functions but has suboptimal DNA replication potential. Introduction of this mutant into a viral life cycle model results in the failure to establish viral episomes. The results present a potential new antiviral target, the E2-TopBP1 interaction, and increase our understanding of the viral life cycle, suggesting that the E2-TopBP1 interaction is essential. There are more than 100 types of human papillomavirus (HPV) involved in a host of epithelial lesions, ranging from hand warts and genital warts to cervical cancer (69). So-called high-risk HPVs are those associated with cancer, and type 16 is the most commonly detected, being present in ca. 50% of cervical carcinomas and increasingly detected in head and neck cancers (30). All HPV encode two proteins, E1 and E2, required for replication of their double-stranded DNA genome in association with cellular partner proteins. The E2 protein forms homodimers and binds to 12-bp palindromic sequences surrounding the origin of replication and via a protein-protein interaction recruits the E1 protein to the A/T-rich origin (9,40,61). E1 then forms a dihexameric helicase that interacts with the cellular DNA polymerase machinery, resulting in DNA replication initiation (36,38,46,55). The origin of replication is located in the long control region (LCR), a noncoding part of the genome that controls the initial transcription from the viral genome by cellular factors (50). The E2 protein can also regulate viral genome transcription; it can act as either an activator or a repressor of viral oncogene expression depending upon E2 levels and the cell type under study (10,15,60). The carboxyl terminus domain of E2 is required for homodimerization and DNA binding, while the amino terminus interacts with E1 and a number of cellular transcription factors (16,47,54,56,63). E2 can also associate with mitotic chromatin and is proposed as a viral genome segregation fact...

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“…TopBP1 and TopBP1; it could also be due to the natural stickiness of E2 to beads used in these coimmunoprecipitation experiments (14,18). What is clear from this experiment is that E2…”

Section: Resultsmentioning

confidence: 97%

Section: Resultsmentioning

confidence: 99%

An Interaction between Human Papillomavirus 16 E2 and TopBP1 Is Required for Optimum Viral DNA Replication and Episomal Genome Establishment

Donaldson

Mackintosh

Bodily

et al. 2012

J Virol

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“…WRN, BLM, and RECQ1) (32), suggests that that the ability of ChlR1 to disrupt protein-DNA complexes is biochemically unusual and may be important for its cellular function to preserve fork structure necessary for sister chromatid cohesion and/or participate in DNA repair or other processes. For example, ChlR1 was shown to be required for papillomavirus E2 protein loading onto mitotic chromosomes during DNA replication for the viral genome to be maintained and segregated (19,43). The functions of the ChlR1 motor ATPase in this process are not well understood.…”

Section: Discussionmentioning

confidence: 99%

Biochemical Characterization of Warsaw Breakage Syndrome Helicase

Sommers

Khan

et al. 2012

Journal of Biological Chemistry

137

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Background: Mutations in ChlR1 (DDX11) are linked to Warsaw breakage syndrome. Results: ChlR1 unwinds forked duplex, 5Ј flap, D-loop, and two-stranded antiparallel G-quadruplex substrates, whereas a patient-derived mutation abolishes helicase activity. Conclusion: ChlR1 helicase unwinds key intermediates of DNA replication and recombination. Significance: Inactivation of catalytic activity by Warsaw breakage syndrome mutation suggests that ChlR1 helicase function is important in vivo.

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“…The actual mechanisms through which the E2 protein tethers papillomaviral episomes to host chromosomes are the subject of intense debate [46]. Using synchronised live cells, Feeney et al [47] have shown that the DNA helicase ChlR1 is required for the association of BPV-1 E2 with chromosomes. In their recent paper, the authors proposed that ChlR1 is required for loading the E2-associated viral genomes onto chromosomes during the S-phase, but not for their retention during mitosis.…”

Section: Bpv Persistence Latency and Transmissionmentioning

confidence: 99%