Definition of the p53 functional domains necessary for inducing apoptosis.
The p53 protein contains several functional domains necessary for inducing cell cycle arrest and apoptosis. The C-terminal basic domain within residues 364-393 and the proline-rich domain within residues 64-91 are required for apoptotic activity. In addition, activation domain 2 within residues 43-63 is necessary for apoptotic activity when the N-terminal activation domain 1 within residues 1-42 is deleted (DeltaAD1) or mutated (AD1(-)). Here we have discovered that an activation domain 2 mutation at residues 53-54 (AD2(-)) abrogates the apoptotic activity but has no significant effect on cell cycle arrest. We have also found that p53-(DeltaAD2), which lacks activation domain 2, is inert in inducing apoptosis. p53-(AD2(-)DeltaBD), which is defective in activation domain 2 and lacks the C-terminal basic domain, p53-(DeltaAD2DeltaBD), which lacks both activation domain 2 and the C-terminal basic domain, and p53-(DeltaPRDDeltaBD), which lacks both the proline-rich domain and the C-terminal basic domain, are also inert in inducing apoptosis. All four mutants are still capable of inducing cell cycle arrest, albeit to a lesser extent than wild-type p53. Interestingly, we have found that deletion of the N-terminal activation domain 1 alleviates the requirement of the C-terminal basic domain for apoptotic activity. Thus, we have generated a small but potent p53-(DeltaAD1DeltaBD) molecule. Furthermore, we have determined that at least two of the three domains (activation domain 1, activation domain 2, and the proline-rich domain), are required for inducing cell cycle arrest. Taken together, our results suggest that activation domain 2 and the proline-rich domain form an activation domain for inducing pro-apoptotic genes or inhibiting anti-apoptotic genes. The C-terminal basic domain is required for maintaining this activation domain competent for transactivation or transrepression.
Zhu
J
J
Institute of Molecular Medicine and Genetics, Medical College of Georgia, Augusta, Georgia 30912, USA.
Zhang
S
S
Jiang
J
J
Chen
X
X
D017209:Apoptosis / Q000502:physiology*; D001483:Base Sequence; D002453:Cell Cycle / Q000502:physiology; D002460:Cell Line; D017931:DNA Primers; D006801:Humans; D016296:Mutagenesis; D011392:Proline / Q000737:chemistry; D011518:Proto-Oncogene Proteins / Q000235:genetics; D019253:Proto-Oncogene Proteins c-bcl-2; D016283:Proto-Oncogene Proteins p21(ras) / Q000235:genetics; D016159:Tumor Suppressor Protein p53 / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D051028:bcl-2-Associated X Protein
D017931:DNA Primers; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D016159:Tumor Suppressor Protein p53; D051028:bcl-2-Associated X Protein; D011392:Proline; C501009:HRAS protein, human; D016283:Proto-Oncogene Proteins p21(ras)