Human papillomavirus E2 protein with single activation domain initiates HPV18 genome replication, but is not sufficient for long-term maintenance of virus genome

Kurg, Reet; Uusen, Piia; Võsa, Liisi; Ustav, Mart

doi:10.1016/j.virol.2010.09.010

Cited by 35 publications

(54 citation statements)

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“…HPV11 E2 expression plasmid pQM11E2co encodes E2 open reading frame (ORF) with a codon-optimized N terminus allowing for a higher E2 expression level in human cell lines and has been described earlier (31). pQM11E2co_N294A encodes HPV11 E2 with a single amino acid substitution in the E2 DNA recognition helix.…”

Section: Methodsmentioning

confidence: 99%

Identification and Analysis of Papillomavirus E2 Protein Binding Sites in the Human Genome

Võsa¹,

Sudakov

Remm

et al. 2012

J Virol

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Papillomavirus E2 protein is required for the replication and maintenance of viral genomes and transcriptional regulation of viral genes. E2 functions through sequence-specific binding to 12-bp DNA motifs-E2 binding sites (E2BS)-in the virus genome. Papillomaviruses are able to establish persistent infection in their host and have developed a long-term relationship with the host cell in order to guarantee the propagation of the virus. In this study, we have analyzed the occurrence and functionality of E2BSs in the human genome. Our computational analysis indicates that most E2BSs in the human genome are found in repetitive DNA regions and have G/C-rich spacer sequences. Using a chromatin immunoprecipitation approach, we show that human papillomavirus type 11 (HPV11) E2 interacts with a subset of cellular E2BSs located in active chromatin regions. Two E2 activities, sequence-specific DNA binding and interaction with cellular Brd4 protein, are important for E2 binding to consensus sites. E2 binding to cellular E2BSs has a moderate or no effect on cellular transcription. We suggest that the preference of HPV E2 proteins for E2BSs with A/T-rich spacers, which are present in the viral genomes and underrepresented in the human genome, ensures E2 binding to specific binding sites in the virus genome and may help to prevent extensive and possibly detrimental changes in cellular transcription in response to the viral protein.H uman papillomaviruses (HPVs)are small DNA viruses that infect cutaneous or mucosal epithelium and are associated with cervical carcinoma and other anogenital cancers, as well as head, neck, and nonmelanoma skin cancers, in humans. The viral E2 protein is the main regulator of the papillomavirus life cycle. E2 is a modular sequence-specific DNA-binding protein with an N-terminal transactivation domain, a central hinge region, and a C-terminal DNA-binding and dimerization domain (DBD) (18). E2 recognizes the palindromic DNA motif ACCGN 4 CGGT, which is present in multiple copies within the upstream regulatory region (URR) of the viral genome (3,21,34). Interaction with these motifs enables the E2 protein to recruit viral helicase E1 to the origin during the initiation of viral DNA replication (10, 53) and tether viral episomes to mitotic chromosomes or other cellular structures in order to ensure nuclear retention during cell division (5, 23). In addition, E2 functions as a transcription factor and regulates papillomavirus early promoter activity in concert with cellular proteins (11,43,50).E2 binds to DNA as a dimer with an antiparallel ␤-barrel structure; a surface-exposed ␣-helix from each of the monomers makes sequence-specific contacts with the E2 binding site (E2BS) halfsite (ACCG) (19). The 4-nucleotide spacer-N 4 -separating the half-sites is conserved in length and influences E2-binding affinity, although the protein does not make direct contacts with these nucleotides. E2BSs in HPV genomes have A/T-rich spacers (45), and the corresponding E2 proteins generally bind to such sites with a high...

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Section: Methodsmentioning

confidence: 99%

Identification and Analysis of Papillomavirus E2 Protein Binding Sites in the Human Genome

Võsa¹,

Sudakov

Remm

et al. 2012

J Virol

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“…The single-chain E2 heterodimer in the HPV 18 genome initiates genome replication, but is not sufficient for long-term replication of the HPV 18 genome. This is due to the capacity of HPV18 in encoding the repressor E8/E2, which acts as a negative regulator of HPV18 genome replication (Kurg et al, 2010). Moreover, it has been shown that inactivation of E2 in the HPV16 genome increases E6/E7 transcription (Soeda et al, 2006), and that mutation of E8^E2C in the HPV31 or HPV16 genome increases the genome copy number and the E6/E7 transcription, suggesting that the transcriptional repressing by E8^E2C has an important role in viral replication (Lace et al, 2008).…”

Section: E2 Proteinmentioning

confidence: 99%

Human Papillomavirus: Biology and Pathogenesis

Fernandes¹,

Fernandes²

2012

Human Papillomavirus and Related Diseases - From Bench to Bedside - A Clinical Perspective

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“…The repressor proteins encoded by HPVs are similar to the BPV1 E8/E2 protein, since they contain a small conserved E8 ORF (HPV 11,18,31) or fragment of E1 ORF (HPV 11) fused to the C-terminus of E2. Transient over-expression assays have suggested that shorter E2 proteins act as negative regulators of E2 and function as repressors of transcription and replication (Chiang et al, 1991;Doorbar et al, 1990;Hubbert et al, 1988;Kurg et al, 2010;Lim et al, 1998;Stubenrauch et al, 2000). The shorter E2s antagonize the function of full-length E2 by competing for E2 DNA binding sites.…”

Section: E2 Repressors and Heterodimersmentioning

confidence: 99%

“…E2 heterodimers can interact with viral helicase E1, and are able to recruit E1 to the origin of replication and activate the papillomavirus DNA replication in a cell-free system . Replacing the open reading frame of E2 with "single-chain" E2 in the context of BPV1 and HPV18 genome revealed that E2 heterodimer with single activation domain could support transient, but not long-term, replication in cell culture model systems (Kurg et al, 2009;Kurg et al, 2010). The full-length E2 protein is required for long-term papillomavirus DNA replication, the E2 heterodimer with single activation domain is crippled in this function.…”

Section: E2 Repressors and Heterodimersmentioning

confidence: 99%

“…Deletion of the E8 ORF results in robust initial replication of HPV genomes followed by rapid loss of virus episomes from dividing cells. The role of E2 repressors in the virus life cycle is to modulate the activity of full-length E2 protein by preventing the E2 binding to E2BS via binding site competition, and by acting as a repressor recruiting host co-repressor molecules (Kurg et al, 2010;Lambert et al, 1990;Stubenrauch et al, 2000). However, the persistent replication and maintenance of virus genomes is not affected in E8 knock-out genomes of HPV16 and cotton-tail rabbit papillomavirus (CRPV), suggesting that E2 proteins of different papillomaviruses may regulate their expression and through this replication by different ways (Jeckel et al, 2003;Lace et al, 2008).…”

Section: Regulation Of Replication By E2mentioning

confidence: 99%

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