Evidence for coiled-coil dimer formation by an Epstein-Barr virus transactivator that lacks a heptad repeat of leucine residues.
Two regions of the Epstein-Barr virus (EBV) BZLF1 gene product, ZEBRA, share sequence homology with c-Fos, one of which corresponds to the DNA binding domain of c-Fos. ZEBRA does not, however, contain the heptad repeat of leucines present in the dimerization domains of leucine zipper proteins. Here it is shown that ZEBRA binds its recognition sites as a homodimer and that the region adjacent to the basic DNA binding domain is essential for dimerization. This region contains a 4-3 repeat of predominantly hydrophobic residues, which is precisely in register with the hydrophobic heptad repeat present in the leucine zipper proteins with respect to the basic DNA binding domain. A mutational analysis of ZEBRA supports a model for dimerization involving a coiled-coil interaction. These results indicate that a heptad repeat of leucines is not a structural requirement for formation of coiled-coil dimers by transcription factors.
Flemington
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E
Division of Tumor Virology, Dana-Farber Cancer Institute, Boston, MA.
Speck
S H
SH
D000595:Amino Acid Sequence; D004268:DNA-Binding Proteins / Q000235:genetics*; D012321:DNA-Directed RNA Polymerases / Q000378:metabolism; D005814:Genes, Viral; D004854:Herpesvirus 4, Human / Q000235:genetics*; D007930:Leucine; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D010957:Plasmids; D014176:Protein Biosynthesis; D012091:Repetitive Sequences, Nucleic Acid; D012689:Sequence Homology, Nucleic Acid; D015534:Trans-Activators / Q000235:genetics*; D014158:Transcription, Genetic; D014764:Viral Proteins
C063676:BZLF1 protein, Herpesvirus 4, Human; D004268:DNA-Binding Proteins; D015534:Trans-Activators; D014764:Viral Proteins; D012321:DNA-Directed RNA Polymerases; D007930:Leucine