title: 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.
abstract: The bovine papillomavirus type 1 E2 open reading frame encodes three proteins involved in viral DNA replication and transcriptional regulation. These polypeptides share a carboxyl-terminal domain with a specific DNA-binding activity; through this domain the E2 polypeptides form dimers. In this study, we demonstrate the inhibition of E2 DNA binding in vitro by reagents that oxidize or otherwise chemically modify the free sulfhydryl groups of reactive cysteine residues. However, these reagents had no effect on DNA-binding activity when the E2 polypeptide was first bound to DNA, suggesting that the free sulfhydryl group(s) may be protected by DNA binding. Sensitivity to sulfhydryl modification was mapped to a cysteine residue at position 340 in the E2 DNA-binding domain, an amino acid that is highly conserved among the E2 proteins of different papillomaviruses. Replacement of this residue with other amino acids abrogated the sensitivity to oxidation-reduction changes but did not affect the DNA-binding property of the E2 protein. These results suggest that papillomavirus DNA replication and transcriptional regulation could be modulated through the E2 proteins by changes in the intracellular redox environment. Furthermore, a motif consisting of a reactive cysteine residue carboxyl-terminal to a lysine residue in a basic region of the DNA-binding domain is a feature common to a number of transcriptional regulatory proteins that, like E2, are subject to redox regulation. Thus, posttranslational regulation of the activity of these proteins by the intracellular redox environment may be a general phenomenon.
authors.affiliation: Laboratory of Tumor Virus Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892.
authors.forename: A A
authors.initials: AA
authors.lastname: McBride
authors.forename: R D
authors.initials: RD
authors.lastname: Klausner
authors.forename: P M
authors.initials: PM
authors.lastname: Howley
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D052688:Bovine papillomavirus 1 / Q000235:genetics* / Q000378:metabolism; D003545:Cysteine; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D003958:Diamide / Q000494:pharmacology; D004220:Disulfides / Q000378:metabolism; D005033:Ethylmaleimide / Q000494:pharmacology; D008969:Molecular Sequence Data; D015345:Oligonucleotide Probes; D009856:Oncogene Proteins, Viral / Q000235:genetics / Q000378:metabolism*; D016366:Open Reading Frames; D010957:Plasmids; D014176:Protein Biosynthesis; D011817:Rabbits; D012156:Reticulocytes / Q000378:metabolism; D012689:Sequence Homology, Nucleic Acid; D013439:Sulfhydryl Reagents / Q000494:pharmacology*; D014158:Transcription, Genetic
chemical_list: D004268:DNA-Binding Proteins; D004220:Disulfides; D015345:Oligonucleotide Probes; D009856:Oncogene Proteins, Viral; D013439:Sulfhydryl Reagents; C076036:oncogene protein E2, Human papillomavirus type 1; D003958:Diamide; D003545:Cysteine; D005033:Ethylmaleimide