Distance constraints and stereospecific alignment requirements characteristic of p53 DNA-binding consensus sequence homologies.
We present evidence in favor of the position that some mutant p53 proteins retain the ability to trans-activate downstream genes through p53 DNA-binding consensus sequence (CS) homologies. We tested one cell line possessing high levels of mutant p53 and found that this mutant p53 is highly active in trans-activating one CS homology, moderately active in trans-activating a second sequence and inactive in modulating a third sequence. We tested a second cell line, also possessing high levels of mutant p53 and found the same pattern of activation. In addition we find that inter-motif distance [represented by N in RRRCWWGYYY(N)RRRCWWGYYY] is very important in determining the relative binding affinity of a given CS homology for wild-type or mutant p53. Our studies suggest that stereospecific alignment of the DNA-binding motifs within the CS may favor binding of wild-type p53 while misalignment may favor binding of mutant p53. Furthermore, we find that the maximum distances at which p53 DNA-binding CS homologies are functionally active vary for different sequences. Introduction of as few as 200 bp between one CS homology and the downstream TATA box can eliminate a 45-fold p53-mediated transactivation. We present evidence that the composition of the DNA which flanks a p53 DNA-binding consensus sequence may also modulate trans-activation.
Cook
J L
JL
Division of Research, Alton Ochsner Medical Foundation, New Orleans, Louisiana, USA 70121.
Ré
R N
RN
Giardina
J F
JF
Fontenot
F E
FE
Cheng
D Y
DY
Alam
J
J
D000595:Amino Acid Sequence; D001483:Base Sequence; D002460:Cell Line; D016384:Consensus Sequence; D017931:DNA Primers; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D008156:Luciferases / Q000032:analysis / Q000096:biosynthesis; D008969:Molecular Sequence Data; D009154:Mutation; D016133:Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid; D012689:Sequence Homology, Nucleic Acid; D016385:TATA Box; D015533:Transcriptional Activation; D014162:Transfection; D014407:Tumor Cells, Cultured; D016159:Tumor Suppressor Protein p53 / Q000737:chemistry* / Q000378:metabolism*
D017931:DNA Primers; D004268:DNA-Binding Proteins; D016159:Tumor Suppressor Protein p53; D008156:Luciferases