Skip to main content
PMC home page
Journal of Virology logoLink to Journal of Virology
. 1997 May;71(5):3652–3665. doi: 10.1128/jvi.71.5.3652-3665.1997

A papillomavirus E2 phosphorylation mutant exhibits normal transient replication and transcription but is defective in transformation and plasmid retention.

C W Lehman 1, D S King 1, M R Botchan 1
PMCID: PMC191514  PMID: 9094639

Abstract

Papillomavirus DNA persists in infected cells as a nuclear plasmid, causing epithelial lesions in many hosts, including humans. The viral protein E2 is required for both replication and transcription to facilitate this persistence. Bovine papillomavirus E2 protein is phosphorylated at two predominant sites. Phosphorylation of one of these sites (serine 301) inhibits replication of the genome. Using mass spectrometry and Edman sequencing, we have mapped additional phosphorylation sites in tryptic peptides to positions which lie primarily in the putatively unstructured hinge region of E2. Mutation of the major sites facilitates transformation in the absence of viral repressors and only has a minor effect on transformation when the repressors are present. Mutation of the major phosphorylation sites combined with one additional change at a newly discovered site (serine 235) blocks transformation. Transformation can be restored by mutating this residue to aspartic acid, mimicking a phosphorylated amino acid, suggesting that phosphorylation is key to the regulation. Transformation by the mutant genome can also be rescued by ectopic expression of the E2 enhancer protein, demonstrating a loss of function by the mutant protein and not a toxic defect. In transient assays, phosphorylation site mutants of E2 protein were normal for all viral functions tested, including replication, transcriptional activation and repression (by the overlapping mutant repressors), protein accumulation, and surprisingly, viral oncogene E5 promoter activation. While the mutant genome transiently replicated to high levels, stable replication was defective, suggesting that a function of E2 required for plasmid retention is regulated by phosphorylation.

Full Text

The Full Text of this article is available as a PDF (1.1 MB).

Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Arfin S. M., Bradshaw R. A. Cotranslational processing and protein turnover in eukaryotic cells. Biochemistry. 1988 Oct 18;27(21):7979–7984. doi: 10.1021/bi00421a001. [DOI] [PubMed] [Google Scholar]
  2. Baker C. C., Howley P. M. Differential promoter utilization by the bovine papillomavirus in transformed cells and productively infected wart tissues. EMBO J. 1987 Apr;6(4):1027–1035. doi: 10.1002/j.1460-2075.1987.tb04855.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Bialojan C., Takai A. Inhibitory effect of a marine-sponge toxin, okadaic acid, on protein phosphatases. Specificity and kinetics. Biochem J. 1988 Nov 15;256(1):283–290. doi: 10.1042/bj2560283. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. Brokaw J. L., Blanco M., McBride A. A. Amino acids critical for the functions of the bovine papillomavirus type 1 E2 transactivator. J Virol. 1996 Jan;70(1):23–29. doi: 10.1128/jvi.70.1.23-29.1996. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Chiang C. M., Dong G., Broker T. R., Chow L. T. Control of human papillomavirus type 11 origin of replication by the E2 family of transcription regulatory proteins. J Virol. 1992 Sep;66(9):5224–5231. doi: 10.1128/jvi.66.9.5224-5231.1992. [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. Choe J., Vaillancourt P., Stenlund A., Botchan M. Bovine papillomavirus type 1 encodes two forms of a transcriptional repressor: structural and functional analysis of new viral cDNAs. J Virol. 1989 Apr;63(4):1743–1755. doi: 10.1128/jvi.63.4.1743-1755.1989. [DOI] [PMC free article] [PubMed] [Google Scholar]
  7. Cohen P., Klumpp S., Schelling D. L. An improved procedure for identifying and quantitating protein phosphatases in mammalian tissues. FEBS Lett. 1989 Jul 3;250(2):596–600. doi: 10.1016/0014-5793(89)80803-8. [DOI] [PubMed] [Google Scholar]
  8. DiMaio D., Guralski D., Schiller J. T. Translation of open reading frame E5 of bovine papillomavirus is required for its transforming activity. Proc Natl Acad Sci U S A. 1986 Mar;83(6):1797–1801. doi: 10.1073/pnas.83.6.1797. [DOI] [PMC free article] [PubMed] [Google Scholar]
  9. DiMaio D. Nonsense mutation in open reading frame E2 of bovine papillomavirus DNA. J Virol. 1986 Feb;57(2):475–480. doi: 10.1128/jvi.57.2.475-480.1986. [DOI] [PMC free article] [PubMed] [Google Scholar]
  10. Dostatni N., Thierry F., Yaniv M. A dimer of BPV-1 E2 containing a protease resistant core interacts with its DNA target. EMBO J. 1988 Dec 1;7(12):3807–3816. doi: 10.1002/j.1460-2075.1988.tb03265.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
  11. Dvoretzky I., Shober R., Chattopadhyay S. K., Lowy D. R. A quantitative in vitro focus assay for bovine papilloma virus. Virology. 1980 Jun;103(2):369–375. doi: 10.1016/0042-6822(80)90195-6. [DOI] [PubMed] [Google Scholar]
  12. Ferguson M. K., Botchan M. R. Genetic analysis of the activation domain of bovine papillomavirus protein E2: its role in transcription and replication. J Virol. 1996 Jul;70(7):4193–4199. doi: 10.1128/jvi.70.7.4193-4199.1996. [DOI] [PMC free article] [PubMed] [Google Scholar]
  13. Giri I., Yaniv M. Structural and mutational analysis of E2 trans-activating proteins of papillomaviruses reveals three distinct functional domains. EMBO J. 1988 Sep;7(9):2823–2829. doi: 10.1002/j.1460-2075.1988.tb03138.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
  14. Groff D. E., Lancaster W. D. Genetic analysis of the 3' early region transformation and replication functions of bovine papillomavirus type 1. Virology. 1986 Apr 15;150(1):221–230. doi: 10.1016/0042-6822(86)90281-3. [DOI] [PubMed] [Google Scholar]
  15. Ham J., Steger G., Yaniv M. Cooperativity in vivo between the E2 transactivator and the TATA box binding protein depends on core promoter structure. EMBO J. 1994 Jan 1;13(1):147–157. doi: 10.1002/j.1460-2075.1994.tb06244.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
  16. Hegde R. S., Grossman S. R., Laimins L. A., Sigler P. B. Crystal structure at 1.7 A of the bovine papillomavirus-1 E2 DNA-binding domain bound to its DNA target. Nature. 1992 Oct 8;359(6395):505–512. doi: 10.1038/359505a0. [DOI] [PubMed] [Google Scholar]
  17. Hirt B. Selective extraction of polyoma DNA from infected mouse cell cultures. J Mol Biol. 1967 Jun 14;26(2):365–369. doi: 10.1016/0022-2836(67)90307-5. [DOI] [PubMed] [Google Scholar]
  18. Hoppe-Seyler F., Butz K. Cellular control of human papillomavirus oncogene transcription. Mol Carcinog. 1994 Jul;10(3):134–141. doi: 10.1002/mc.2940100304. [DOI] [PubMed] [Google Scholar]
  19. Hubbert N. L., Schiller J. T., Lowy D. R., Androphy E. J. Bovine papilloma virus-transformed cells contain multiple E2 proteins. Proc Natl Acad Sci U S A. 1988 Aug;85(16):5864–5868. doi: 10.1073/pnas.85.16.5864. [DOI] [PMC free article] [PubMed] [Google Scholar]
  20. Kadonaga J. T., Tjian R. Affinity purification of sequence-specific DNA binding proteins. Proc Natl Acad Sci U S A. 1986 Aug;83(16):5889–5893. doi: 10.1073/pnas.83.16.5889. [DOI] [PMC free article] [PubMed] [Google Scholar]
  21. Krysan P. J., Haase S. B., Calos M. P. Isolation of human sequences that replicate autonomously in human cells. Mol Cell Biol. 1989 Mar;9(3):1026–1033. doi: 10.1128/mcb.9.3.1026. [DOI] [PMC free article] [PubMed] [Google Scholar]
  22. Lambert P. F., Hubbert N. L., Howley P. M., Schiller J. T. Genetic assignment of multiple E2 gene products in bovine papillomavirus-transformed cells. J Virol. 1989 Jul;63(7):3151–3154. doi: 10.1128/jvi.63.7.3151-3154.1989. [DOI] [PMC free article] [PubMed] [Google Scholar]
  23. Lambert P. F., Monk B. C., Howley P. M. Phenotypic analysis of bovine papillomavirus type 1 E2 repressor mutants. J Virol. 1990 Feb;64(2):950–956. doi: 10.1128/jvi.64.2.950-956.1990. [DOI] [PMC free article] [PubMed] [Google Scholar]
  24. Leptak C., Ramon y Cajal S., Kulke R., Horwitz B. H., Riese D. J., 2nd, Dotto G. P., DiMaio D. Tumorigenic transformation of murine keratinocytes by the E5 genes of bovine papillomavirus type 1 and human papillomavirus type 16. J Virol. 1991 Dec;65(12):7078–7083. doi: 10.1128/jvi.65.12.7078-7083.1991. [DOI] [PMC free article] [PubMed] [Google Scholar]
  25. Li R., Knight J. D., Jackson S. P., Tjian R., Botchan M. R. Direct interaction between Sp1 and the BPV enhancer E2 protein mediates synergistic activation of transcription. Cell. 1991 May 3;65(3):493–505. doi: 10.1016/0092-8674(91)90467-d. [DOI] [PubMed] [Google Scholar]
  26. Li R., Knight J., Bream G., Stenlund A., Botchan M. Specific recognition nucleotides and their DNA context determine the affinity of E2 protein for 17 binding sites in the BPV-1 genome. Genes Dev. 1989 Apr;3(4):510–526. doi: 10.1101/gad.3.4.510. [DOI] [PubMed] [Google Scholar]
  27. Luckow B., Schütz G. CAT constructions with multiple unique restriction sites for the functional analysis of eukaryotic promoters and regulatory elements. Nucleic Acids Res. 1987 Jul 10;15(13):5490–5490. doi: 10.1093/nar/15.13.5490. [DOI] [PMC free article] [PubMed] [Google Scholar]
  28. Lusky M., Botchan M. R. Characterization of the bovine papilloma virus plasmid maintenance sequences. Cell. 1984 Feb;36(2):391–401. doi: 10.1016/0092-8674(84)90232-0. [DOI] [PubMed] [Google Scholar]
  29. Lusky M., Fontane E. Formation of the complex of bovine papillomavirus E1 and E2 proteins is modulated by E2 phosphorylation and depends upon sequences within the carboxyl terminus of E1. Proc Natl Acad Sci U S A. 1991 Jul 15;88(14):6363–6367. doi: 10.1073/pnas.88.14.6363. [DOI] [PMC free article] [PubMed] [Google Scholar]
  30. Mann M., Wilm M. Electrospray mass spectrometry for protein characterization. Trends Biochem Sci. 1995 Jun;20(6):219–224. doi: 10.1016/s0968-0004(00)89019-2. [DOI] [PubMed] [Google Scholar]
  31. McBride A. A., Bolen J. B., Howley P. M. Phosphorylation sites of the E2 transcriptional regulatory proteins of bovine papillomavirus type 1. J Virol. 1989 Dec;63(12):5076–5085. doi: 10.1128/jvi.63.12.5076-5085.1989. [DOI] [PMC free article] [PubMed] [Google Scholar]
  32. McBride A. A., Byrne J. C., Howley P. M. E2 polypeptides encoded by bovine papillomavirus type 1 form dimers through the common carboxyl-terminal domain: transactivation is mediated by the conserved amino-terminal domain. Proc Natl Acad Sci U S A. 1989 Jan;86(2):510–514. doi: 10.1073/pnas.86.2.510. [DOI] [PMC free article] [PubMed] [Google Scholar]
  33. McBride A. A., Howley P. M. Bovine papillomavirus with a mutation in the E2 serine 301 phosphorylation site replicates at a high copy number. J Virol. 1991 Dec;65(12):6528–6534. doi: 10.1128/jvi.65.12.6528-6534.1991. [DOI] [PMC free article] [PubMed] [Google Scholar]
  34. McBride A. A., Klausner R. D., Howley P. M. Conserved cysteine residue in the DNA-binding domain of the bovine papillomavirus type 1 E2 protein confers redox regulation of the DNA-binding activity in vitro. Proc Natl Acad Sci U S A. 1992 Aug 15;89(16):7531–7535. doi: 10.1073/pnas.89.16.7531. [DOI] [PMC free article] [PubMed] [Google Scholar]
  35. McBride A. A., Schlegel R., Howley P. M. The carboxy-terminal domain shared by the bovine papillomavirus E2 transactivator and repressor proteins contains a specific DNA binding activity. EMBO J. 1988 Feb;7(2):533–539. doi: 10.1002/j.1460-2075.1988.tb02842.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
  36. McVey D., Brizuela L., Mohr I., Marshak D. R., Gluzman Y., Beach D. Phosphorylation of large tumour antigen by cdc2 stimulates SV40 DNA replication. Nature. 1989 Oct 12;341(6242):503–507. doi: 10.1038/341503a0. [DOI] [PubMed] [Google Scholar]
  37. Neary K., DiMaio D. Open reading frames E6 and E7 of bovine papillomavirus type 1 are both required for full transformation of mouse C127 cells. J Virol. 1989 Jan;63(1):259–266. doi: 10.1128/jvi.63.1.259-266.1989. [DOI] [PMC free article] [PubMed] [Google Scholar]
  38. Nordeen S. K. Luciferase reporter gene vectors for analysis of promoters and enhancers. Biotechniques. 1988 May;6(5):454–458. [PubMed] [Google Scholar]
  39. Piirsoo M., Ustav E., Mandel T., Stenlund A., Ustav M. Cis and trans requirements for stable episomal maintenance of the BPV-1 replicator. EMBO J. 1996 Jan 2;15(1):1–11. [PMC free article] [PubMed] [Google Scholar]
  40. Prakash S. S., Grossman S. R., Pepinsky R. B., Laimins L. A., Androphy E. J. Amino acids necessary for DNA contact and dimerization imply novel motifs in the papillomavirus E2 trans-activator. Genes Dev. 1992 Jan;6(1):105–116. doi: 10.1101/gad.6.1.105. [DOI] [PubMed] [Google Scholar]
  41. Prakash S. S., Horwitz B. H., Zibello T., Settleman J., DiMaio D. Bovine papillomavirus E2 gene regulates expression of the viral E5 transforming gene. J Virol. 1988 Oct;62(10):3608–3613. doi: 10.1128/jvi.62.10.3608-3613.1988. [DOI] [PMC free article] [PubMed] [Google Scholar]
  42. Rabson M. S., Yee C., Yang Y. C., Howley P. M. Bovine papillomavirus type 1 3' early region transformation and plasmid maintenance functions. J Virol. 1986 Nov;60(2):626–634. doi: 10.1128/jvi.60.2.626-634.1986. [DOI] [PMC free article] [PubMed] [Google Scholar]
  43. Rank N. M., Lambert P. F. Bovine papillomavirus type 1 E2 transcriptional regulators directly bind two cellular transcription factors, TFIID and TFIIB. J Virol. 1995 Oct;69(10):6323–6334. doi: 10.1128/jvi.69.10.6323-6334.1995. [DOI] [PMC free article] [PubMed] [Google Scholar]
  44. Rechsteiner M. PEST sequences are signals for rapid intracellular proteolysis. Semin Cell Biol. 1990 Dec;1(6):433–440. [PubMed] [Google Scholar]
  45. Riese D. J., 2nd, Settleman J., Neary K., DiMaio D. Bovine papillomavirus E2 repressor mutant displays a high-copy-number phenotype and enhanced transforming activity. J Virol. 1990 Feb;64(2):944–949. doi: 10.1128/jvi.64.2.944-949.1990. [DOI] [PMC free article] [PubMed] [Google Scholar]
  46. Schiffman M. H., Bauer H. M., Hoover R. N., Glass A. G., Cadell D. M., Rush B. B., Scott D. R., Sherman M. E., Kurman R. J., Wacholder S. Epidemiologic evidence showing that human papillomavirus infection causes most cervical intraepithelial neoplasia. J Natl Cancer Inst. 1993 Jun 16;85(12):958–964. doi: 10.1093/jnci/85.12.958. [DOI] [PubMed] [Google Scholar]
  47. Schiller J. T., Vass W. C., Vousden K. H., Lowy D. R. E5 open reading frame of bovine papillomavirus type 1 encodes a transforming gene. J Virol. 1986 Jan;57(1):1–6. doi: 10.1128/jvi.57.1.1-6.1986. [DOI] [PMC free article] [PubMed] [Google Scholar]
  48. Schlegel R., Wade-Glass M., Rabson M. S., Yang Y. C. The E5 transforming gene of bovine papillomavirus encodes a small, hydrophobic polypeptide. Science. 1986 Jul 25;233(4762):464–467. doi: 10.1126/science.3014660. [DOI] [PubMed] [Google Scholar]
  49. Sedman J., Stenlund A. Co-operative interaction between the initiator E1 and the transcriptional activator E2 is required for replicator specific DNA replication of bovine papillomavirus in vivo and in vitro. EMBO J. 1995 Dec 15;14(24):6218–6228. doi: 10.1002/j.1460-2075.1995.tb00312.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
  50. Sefton B. M., Hunter T., Beemon K., Eckhart W. Evidence that the phosphorylation of tyrosine is essential for cellular transformation by Rous sarcoma virus. Cell. 1980 Jul;20(3):807–816. doi: 10.1016/0092-8674(80)90327-x. [DOI] [PubMed] [Google Scholar]
  51. Spalholz B. A. Importance of the bovine papillomavirus P2443 promoter in the regulation of E2 and E5 expression. J Virol. 1993 Oct;67(10):6278–6284. doi: 10.1128/jvi.67.10.6278-6284.1993. [DOI] [PMC free article] [PubMed] [Google Scholar]
  52. Spalholz B. A., Vande Pol S. B., Howley P. M. Characterization of the cis elements involved in basal and E2-transactivated expression of the bovine papillomavirus P2443 promoter. J Virol. 1991 Feb;65(2):743–753. doi: 10.1128/jvi.65.2.743-753.1991. [DOI] [PMC free article] [PubMed] [Google Scholar]
  53. Szymanski P., Stenlund A. Regulation of early gene expression from the bovine papillomavirus genome in transiently transfected C127 cells. J Virol. 1991 Nov;65(11):5710–5720. doi: 10.1128/jvi.65.11.5710-5720.1991. [DOI] [PMC free article] [PubMed] [Google Scholar]
  54. Tyers M., Tokiwa G., Nash R., Futcher B. The Cln3-Cdc28 kinase complex of S. cerevisiae is regulated by proteolysis and phosphorylation. EMBO J. 1992 May;11(5):1773–1784. doi: 10.1002/j.1460-2075.1992.tb05229.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
  55. Ustav M., Stenlund A. Transient replication of BPV-1 requires two viral polypeptides encoded by the E1 and E2 open reading frames. EMBO J. 1991 Feb;10(2):449–457. doi: 10.1002/j.1460-2075.1991.tb07967.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
  56. Vaillancourt P., Nottoli T., Choe J., Botchan M. R. The E2 transactivator of bovine papillomavirus type 1 is expressed from multiple promoters. J Virol. 1990 Aug;64(8):3927–3937. doi: 10.1128/jvi.64.8.3927-3937.1990. [DOI] [PMC free article] [PubMed] [Google Scholar]
  57. Vande Pol S. B., Howley P. M. Negative regulation of the bovine papillomavirus E5, E6, and E7 oncogenes by the viral E1 and E2 genes. J Virol. 1995 Jan;69(1):395–402. doi: 10.1128/jvi.69.1.395-402.1995. [DOI] [PMC free article] [PubMed] [Google Scholar]
  58. Winokur P. L., McBride A. A. Separation of the transcriptional activation and replication functions of the bovine papillomavirus-1 E2 protein. EMBO J. 1992 Nov;11(11):4111–4118. doi: 10.1002/j.1460-2075.1992.tb05504.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
  59. Wysokenski D. A., Yates J. L. Multiple EBNA1-binding sites are required to form an EBNA1-dependent enhancer and to activate a minimal replicative origin within oriP of Epstein-Barr virus. J Virol. 1989 Jun;63(6):2657–2666. doi: 10.1128/jvi.63.6.2657-2666.1989. [DOI] [PMC free article] [PubMed] [Google Scholar]
  60. Yang L., Li R., Mohr I. J., Clark R., Botchan M. R. Activation of BPV-1 replication in vitro by the transcription factor E2. Nature. 1991 Oct 17;353(6345):628–632. doi: 10.1038/353628a0. [DOI] [PubMed] [Google Scholar]
  61. Yang L., Mohr I., Li R., Nottoli T., Sun S., Botchan M. Transcription factor E2 regulates BPV-1 DNA replication in vitro by direct protein-protein interaction. Cold Spring Harb Symp Quant Biol. 1991;56:335–346. doi: 10.1101/sqb.1991.056.01.040. [DOI] [PubMed] [Google Scholar]
  62. Yang Y. C., Okayama H., Howley P. M. Bovine papillomavirus contains multiple transforming genes. Proc Natl Acad Sci U S A. 1985 Feb;82(4):1030–1034. doi: 10.1073/pnas.82.4.1030. [DOI] [PMC free article] [PubMed] [Google Scholar]
  63. Yang Y. C., Spalholz B. A., Rabson M. S., Howley P. M. Dissociation of transforming and trans-activation functions for bovine papillomavirus type 1. Nature. 1985 Dec 12;318(6046):575–577. doi: 10.1038/318575a0. [DOI] [PubMed] [Google Scholar]
  64. zur Hausen H. Human papillomaviruses in the pathogenesis of anogenital cancer. Virology. 1991 Sep;184(1):9–13. doi: 10.1016/0042-6822(91)90816-t. [DOI] [PubMed] [Google Scholar]

Articles from Journal of Virology are provided here courtesy of American Society for Microbiology (ASM)

RESOURCES