How transcriptional activators bind target proteins.
The product of the proto-oncogene c-myc influences many cellular processes through the regulation of specific target genes. Through its transactivation domain (TAD), c-Myc protein interacts with several transcription factors, including TATA-binding protein (TBP). We present data that suggest that in contrast to some other transcriptional activators, an extended length of the c-Myc TAD is required for its binding to TBP. Our data also show that this interaction is a multistep process, in which a rapidly forming low affinity complex slowly converts to a more stable form. The initial complex formation results from ionic or polar interactions, whereas the slow conversion to a more stable form is hydrophobic in nature. Based on our results, we suggest two alternative models for activation domain/target protein interactions, which together provide a single universal paradigm for understanding activator-target factor interactions.
Hermann
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Department of Natural Sciences, Södertörns högskola, Box 4101, S-14104 Huddinge, Sweden. Stefan.Hermann@sh.se
Berndt
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KD
Wright
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AP
D001665:Binding Sites; D004268:DNA-Binding Proteins / Q000378:metabolism*; D019277:Entropy; D008956:Models, Chemical; D008958:Models, Molecular; D010446:Peptide Fragments / Q000378:metabolism; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D016271:Proto-Oncogene Proteins c-myc / Q000378:metabolism*; D035181:TATA-Box Binding Protein; D015534:Trans-Activators / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism*
D004268:DNA-Binding Proteins; D010446:Peptide Fragments; D016271:Proto-Oncogene Proteins c-myc; D035181:TATA-Box Binding Protein; D015534:Trans-Activators; D014157:Transcription Factors