Site-specific conformational alteration of the Oct-1 POU domain-DNA complex as the basis for differential recognition by Vmw65 (VP16).
We show that the presence of a regulatory cis-acting element that flanks the core octamer site and dictates selectivity in the response to Vmw65 (VP16), while dispensable for POU binding per se, induces a conformational alteration in the nature of the POU domain in the DNA complex. A single substitution in the flanking signal distorts the POU complex and without affecting overall POU binding prevents Vmw65 interaction. Alternatively, substitution of a residue in the homeodomain predicted to contact the GARAT region prevents its recognition even on a wild-type motif, causing a reversion to the DNA binding pattern seen on a cellular motif and at the same time inefficient recognition by Vmw65. The results indicate that Vmw65 recognizes a particular POU domain conformation induced by the presence of the flanking GARAT region.
Walker
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S
Marie Curie Research Institute, Oxted, Surrey, England.
Hayes
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O'Hare
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P
D001483:Base Sequence; D004247:DNA / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D006367:HeLa Cells; D017405:Herpes Simplex Virus Protein Vmw65 / Q000378:metabolism*; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism; D051863:Host Cell Factor C1; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D050811:Octamer Transcription Factor-1; D050809:POU Domain Factors; D011485:Protein Binding; D011487:Protein Conformation; D012045:Regulatory Sequences, Nucleic Acid; D013329:Structure-Activity Relationship; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic; D015533:Transcriptional Activation
D004268:DNA-Binding Proteins; C497692:HCFC1 protein, human; D017405:Herpes Simplex Virus Protein Vmw65; D018398:Homeodomain Proteins; D051863:Host Cell Factor C1; D050811:Octamer Transcription Factor-1; D050809:POU Domain Factors; C494165:POU2F1 protein, human; D014157:Transcription Factors; D004247:DNA