Human papillomavirus type 18 E7 protein requires intact Cys-X-X-Cys motifs for zinc binding, dimerization, and transformation but not for Rb binding

Maritza C. Mcintyre, Mark G. Frattini, Steven R. Grossman, Laimonis A. Laimins*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

110 Scopus citations

Abstract

Human papillomavirus type 18 (HPV-18) E7 proteins bind zinc through Cys- X-X-Cys repeats located at the C terminus of the protein. In order to examine the role of these cysteine motifs in E7 function, we expressed the HPV-18 E7 protein in bacteria and found that purified E7 forms a dimer through interactions with zinc. Mutants with single mutations within the Cys-X-X-Cys motifs bound a reduced level of zinc in a zinc blot assay, while a double mutant lost all zinc-binding activity. When expressed in vivo, none of the mutants cooperated with an activated ras oncogene to transform primary rat embryo fibroblasts, but all mutants retained nearly wild-type Rb-binding activity. The results indicate that the cysteine motifs play an important role in transformation by HPV-18 E7 but do not contribute to Rb binding.

Original languageEnglish (US)
Pages (from-to)3142-3150
Number of pages9
JournalJournal of virology
Volume67
Issue number6
DOIs
StatePublished - 1993

ASJC Scopus subject areas

  • Microbiology
  • Immunology
  • Insect Science
  • Virology

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