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Human papillomavirus-16 E7 protein inhibits the DNA interaction of the TATA binding transcription factor

Edio Maldonado1, María Eugenia Cabrejos, Lawrence Banks

  • 1Programa de Biologìa Celular y Molecular, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago, Chile. emaldona@machi.med.uchile.cl

Journal of Cellular Biochemistry
|April 23, 2002
PubMed

Insights

The human papillomavirus type 16 E7 protein inhibits TBP DNA binding. This inhibition is enhanced by protein kinase CK2 phosphorylation and requires E7

Area of Science:

  • Molecular Biology
  • Virology
  • Biochemistry

Background:

  • The HPV-16 E7 protein interacts with TBP (TATA-binding protein).
  • This interaction involves E7's carboxy-terminal residues and is modulated by CK2 phosphorylation.
  • Previous studies indicate a link between E7-TBP interaction, CK2 phosphorylation, and E7's transforming activity, but E7's effect on TBP function was unknown.

Purpose of the Study:

  • To investigate the impact of HPV-16 E7 on TBP's DNA binding activity.
  • To determine if CK2 phosphorylation affects E7's inhibition of TBP DNA binding.
  • To assess the role of the E7-TBP interaction in E7's effect on TBP function.

Main Methods:

  • In vitro DNA binding assays using human and S. pombe TBP.
  • Analysis of wild-type and mutant HPV-16 E7 proteins, including a mutant defective in TBP binding.
  • Investigation of the role of protein kinase CK2 (casein kinase II) phosphorylation.

Main Results:

  • HPV-16 E7 potently inhibits TBP DNA binding activity.
  • CK2 phosphorylation of E7 enhances its inhibitory effect on TBP DNA binding.
  • An E7 mutant unable to bind TBP did not inhibit TBP DNA binding.

Conclusions:

  • The interaction between HPV-16 E7 and TBP leads to the abolition of TBP's DNA binding activity.
  • CK2 phosphorylation enhances the inhibitory capacity of E7 on TBP DNA binding.
  • These findings provide a molecular mechanism for the transcriptional inhibitory effects of HPV-16 E7.

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