Two sequence motifs from HIF-1alpha bind to the DNA-binding site of p53.
There is evidence that hypoxia-inducible factor-1alpha (HIF-1alpha) interacts with the tumor suppressor p53. To characterize the putative interaction, we mapped the binding of the core domain of p53 (p53c) to an array of immobilized HIF-1alpha-derived peptides and found two peptide-sequence motifs that bound to p53c with micromolar affinity in solution. One sequence was adjacent to and the other coincided with the two proline residues of the oxygen-dependent degradation domain (P402 and P564) that act as switches for the oxygen-dependent regulation of HIF-1alpha. The binding affinity was independent of the hydroxylation state of P564. We found from NMR spectroscopy that these sequence motifs bind to the DNA-binding site of p53c. Because the two sequences are homologous and separated by 120 residues, and one is in a largely unstructured transactivation domain, we speculate that each sequence motif in HIF-1alpha binds to a different subunit of the p53 tetramer, leading to very tight binding. The binding data support the proposal that p53 provides a route for the degradation in hypoxic tumor cells of HIF-1alpha that is not hydroxylated at the two proline residues.
Cambridge Centre for Protein Engineering, Medical Research Council Centre, Hills Road, Cambridge CB2 2QH, United Kingdom.
Lars O
LO
Hansson
Assaf
A
Friedler
Stefan
S
Freund
Stefan
S
Rudiger
Alan R
AR
Fersht
D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D001665:Binding Sites; D004247:DNA / Q000378:metabolism; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D008969:Molecular Sequence Data; D010455:Peptides / Q000378:metabolism; D012996:Solutions; D014157:Transcription Factors / Q000378:metabolism*; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*
C497442:HIF1A protein, human; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D010455:Peptides; D012996:Solutions; D014157:Transcription Factors; D016159:Tumor Suppressor Protein p53; D004247:DNA