The transcription factors Elk-1 and serum response factor interact by direct protein-protein contacts mediated by a short region of Elk-1.
Transcriptional induction of the c-fos gene in response to epidermal growth factor stimulation is mediated in part by a ternary nucleoprotein complex within the promoter consisting of serum response factor (SRF), p62TCF/Elk-1 and the serum response element (SRE). Both SRF and p62TCF/Elk-1 contact the DNA and bind in a cooperative manner to the SRE. In this study, we demonstrate that SRF and Elk-1 interact directly in the absence of the SRE. A 30-amino-acid peptide from Elk-1 (B-box) is both necessary and sufficient to mediate protein-protein contacts with SRF. Moreover, the Elk-1 B-box is necessary to enable SRF-dependent binding of an alternative ETS domain (from the transcription factor PU.1) to the c-fos SRE. Mutations in either the Elk-1 B-box or the C-terminal half of the SRF DNA-binding domain (coreSRF) which show reduced ability to form ternary complexes also show greatly reduced protein-protein interactions in the absence of the SRE. Our results clearly demonstrate that direct protein-protein interactions between the transcription factors Elk-1 and SRF, in addition to DNA contacts, contribute to the formation of a ternary complex on the c-fos SRE. We discuss the wider applicability of our results in describing specific protein-protein interactions between short well-defined transcription factor domains.
Shore
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Department of Biochemistry and Genetics, Medical School, University of Newcastle upon Tyne, United Kingdom.
Sharrocks
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D000595:Amino Acid Sequence; D001483:Base Sequence; D001665:Binding Sites; D004247:DNA / Q000378:metabolism; D017931:DNA Primers; D004268:DNA-Binding Proteins / Q000096:biosynthesis / Q000378:metabolism*; D004815:Epidermal Growth Factor / Q000494:pharmacology*; D005786:Gene Expression Regulation / Q000187:drug effects; D016762:Genes, fos; D006801:Humans; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009687:Nuclear Proteins / Q000096:biosynthesis / Q000378:metabolism*; D009838:Oligodeoxyribonucleotides; D010957:Plasmids; D017354:Point Mutation; D016133:Polymerase Chain Reaction; D011485:Protein Binding; D014176:Protein Biosynthesis; D011518:Proto-Oncogene Proteins; D015682:Retroviridae Proteins, Oncogenic / Q000096:biosynthesis / Q000737:chemistry / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D026362:Serum Response Factor; D014157:Transcription Factors / Q000378:metabolism*; D014158:Transcription, Genetic; D050807:ets-Domain Protein Elk-1
D017931:DNA Primers; D004268:DNA-Binding Proteins; C494112:ELK1 protein, human; D009687:Nuclear Proteins; D009838:Oligodeoxyribonucleotides; D011518:Proto-Oncogene Proteins; D015682:Retroviridae Proteins, Oncogenic; D026362:Serum Response Factor; D014157:Transcription Factors; D050807:ets-Domain Protein Elk-1; D004815:Epidermal Growth Factor; D004247:DNA