Wolkowicz R, Peled A, Elkind N B, Rotter V
Department of Cell Biology, Weizmann Institute of Science, Rehovot, Israel.
Proc Natl Acad Sci U S A. 1995 Jul 18;92(15):6842-6. doi: 10.1073/pnas.92.15.6842.
DNA-binding activity of the wild-type p53 is central to its function in vivo. However, recombinant or in vitro translated wild-type p53 proteins, unless modified, are poor DNA binders. The fact that the in vitro produced protein gains DNA-binding activity upon modification at the C terminus raises the possibility that similar mechanisms may exist in the cell. Data presented here show that a C-terminal alternatively spliced wild-type p53 (ASp53) mRNA expressed by bacteria or transcribed in vitro codes for a p53 protein that efficiently binds DNA. Our results support the conclusion that the augmented DNA binding activity of an ASp53 protein is probably due to attenuation of the negative effect residing at the C terminus of the wild-type p53 protein encoded by the regularly spliced mRNA (RSp53) rather than acquisition of additional functionality by the alternatively spliced C' terminus. In addition, we found that ASp53 forms a complex with the non-DNA-binding RSp53, which in turn blocks the DNA-binding activity of ASp53. Interaction between these two wild-type p53 proteins may underline a mechanism that controls the activity of the wild-type p53 protein in the cell.
野生型p53的DNA结合活性是其体内功能的核心。然而，重组的或体外翻译的野生型p53蛋白，除非经过修饰，否则是较差的DNA结合蛋白。体外产生的蛋白在C末端修饰后获得DNA结合活性这一事实，增加了细胞中可能存在类似机制的可能性。此处呈现的数据表明，由细菌表达或体外转录的C末端选择性剪接的野生型p53（ASp53）mRNA编码一种能有效结合DNA的p53蛋白。我们的结果支持这样的结论：ASp53蛋白增强的DNA结合活性可能是由于正常剪接的mRNA（RSp53）编码的野生型p53蛋白C末端的负面影响减弱，而非选择性剪接的C'末端获得了额外功能。此外，我们发现ASp53与非DNA结合的RSp53形成复合物，这反过来又阻断了ASp53的DNA结合活性。这两种野生型p53蛋白之间的相互作用可能是细胞中控制野生型p53蛋白活性机制的基础。
