Transactivation of a bovine papilloma virus transcriptional regulatory element by the E2 gene product

Spalholz, Barbara A.; Yi, Yang; Howley, Peter M.

doi:10.1016/s0092-8674(85)80114-8

Cited by 390 publications

(307 citation statements)

References 45 publications

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“…This 410-amino-acid protein is responsible for the coordination of BPV transcription. E2 binds specifically and with high affinity to the palindrome ACCGN4CGGT (Androphy et al 1987;Moskaluk and Bastia 1988;Li et al 1989;Monini et al 1991) and activates transcription from promoters with these enhancer elements (Spalholz et al 1985;Harrison et al 1987;Haugen et al 1987;Hirochika et al 1987;Spalholz et al 1987;Gius et al 1988;HawleyNelson et al 1988;Moskaluk and Bastia 1988;Li et al 1989;Sousa et al 1990). Genetic studies predict that the ^These authors conttibuted equally to this work.…”

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confidence: 93%

Amino acids necessary for DNA contact and dimerization imply novel motifs in the papillomavirus E2 trans-activator.

et al. 1992

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The bovine papillomavirus E2 protein regulates viral transcription by binding as a dimer to the DNA sequence ACCGN4CGGT. The dimerization and DNA-binding properties are localized within its carboxy-terminal 85 amino acids (325-410). Utilizing random mutagenesis coupled with phenotypic selection in yeast, functionally important amino acids in the DNA-binding domain were identified. Four trans-activation defective point mutants within a short segment (amino acids 337-344) were DNA binding defective but dimeric. The mutation of a conserved tryptophan to serine also eliminated DNA binding, but loss of dimerization was implicated because addition of dimeric monoclonal antibody complemented this defect. A simple assay for £2 dimerization was developed using UV irradiation to produce an interchain cross-link within a dimer. No heterodimeric complexes were formed when pools of E2 of varying lengths were mixed, and only proteins with tryptophan at position 360 could be UV cross-linked. Peptide mapping of irradiated E2 protein localized the cross-link to an 18-amino-acid region bracketing this tryptophan. Substitutions for this tryptophan demonstrated the requirement for a hydrophobic residue at this position, but surprisingly, even alanine was functional. Replacement of this tryptophan with three polar amino acids or glycine eliminated DNA-binding activity, but addition of dimeric monoclonal antibody restored this function. The amino acids that were identified as being involved in DNA contact and dimerization imply that these functions are mediated by novel binding motifs.

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confidence: 93%

Amino acids necessary for DNA contact and dimerization imply novel motifs in the papillomavirus E2 trans-activator.

et al. 1992

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“…The BPV1 E2 can either activate or repress papillomavirus promoters (14)(15)(16). In genital HPVs, the only demonstrated transcriptional regulation by E2 is the repression of the viral early promoters (17)(18)(19)(20)(21), although it can also activate transcription when bound upstream of heterologous promoters.…”

Section: Introductionmentioning

confidence: 99%

Control of HPV 18 DNA replication by cellular and viral transcription factors

et al. 1995

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Papillomavirus replication in vivo requires the interaction of the virally encoded proteins El and E2 with the origin of replication which is localised in the regulatory region (long control region or LCR) of the viral genome. In genital human papillomaviruses (HPVs), the origin overlaps promoter elements of early transcription. In this study, we analysed the replication of HPV18 DNA using the complete LCR containing mutations in transcription regulatory elements. We found that each of the three E2 binding sites proximal to the AT-rich sequence of the origin contributes to the replication rate of DNA, although not identically. In addition, two sequences important for early transcription, an Spi binding site and the TATA box, were also found to play a role in replication. In contrast, two AP1 binding sites required for the enhancer-mediated activation of early transcription did not affect the replication, while other upstream sequences in the LCR did contribute to the replication efficiency. Our results indicate that besides a core origin of replication containing an AT-rich sequence and three E2 binding sites, auxiliary elements affect HPVl 8 DNA replication in the context of the full length LCR, some of which are important for transcription.

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“…This motif has been found in the genomes of all papillomaviruses sequenced to date (14), and is repeated 17 times in the BPV-1 genome, 12 sites being clustered in the viral regulatory region or enhancer (URR), and at least one site being associated with each of the major viral promoters (15). In the bovine system, the E2 protein is a necessary activator of viral transcription capable of stimulating transcription from the BPV E2 conditional enhancer by 300-fold (16)(17)(18)(19)(20)(21). The protein is also required in association with the viral El protein for replication (22,23).…”

Section: Introductionmentioning

confidence: 99%

Kinetic and equilibrium binding studies of the human papillomavirus type-16 transcription regulatory protein E2 interacting with core enhancer elements

Sanders

Maitland

1994

Nucl Acids Res

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The human papillomaviruses (HPVs) are a family of DNA viruses which cause benign tumours of the skin and mucosa that infrequently progress to malignant carcinoma. The E2 open reading frame of HPV is thought to encode a papillomavirus-specific transcription factor which also has a role in viral replication. The E2 proteins of all papillomaviruses studied to date have been shown to bind specifically to the common conserved sequence ACC(N)6GGT found at multiple locations in their genomes. In the case of HPV-16, a 'high risk' genital papillomavirus, the E2 protein is thought to negatively regulate expression of the major viral transforming genes E6 and E7, which have been directly implicated in the oncogenic process. However, little information exists concerning the relative or absolute affinities of the native HPV-16 protein for its palindromic recognition sequences; moreover, interpretation of any transcription or replication phenomena attributed to this protein is more complicated in the absence of such data. Here we describe the overexpression, purification and characterisation of the C-terminal 89 amino acids of the protein encompassing the DNA binding/dimerisation domain. We show that the recombinant protein purified from E.coli by a combination of non-group-specific chromatography steps retains high biological activity and is able to bind to all sites in the HPV-16 genome with high affinity ( -8x 10-11 M). In addition, kinetic studies show that the E2 -DNA complexes are very stable, with half-lives ranging from 2.15 to greater than 240 min, and that nucleotides internal and external to the conserved palindrome appear to influence stability.

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Transactivation of a bovine papilloma virus transcriptional regulatory element by the E2 gene product

Cited by 390 publications

References 45 publications

Amino acids necessary for DNA contact and dimerization imply novel motifs in the papillomavirus E2 trans-activator.

Amino acids necessary for DNA contact and dimerization imply novel motifs in the papillomavirus E2 trans-activator.

Control of HPV 18 DNA replication by cellular and viral transcription factors

Kinetic and equilibrium binding studies of the human papillomavirus type-16 transcription regulatory protein E2 interacting with core enhancer elements

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