Mummenbrauer T, Janus F, Müller B, Wiesmüller L, Deppert W, Grosse F
Heinrich-Pette-Institut für Experimentelle Virologie und Immunologie, Hamburg, Germany.
Cell. 1996 Jun 28;85(7):1089-99. doi: 10.1016/s0092-8674(00)81309-4.
Highly purified p53 protein from different sources was able to degrade DNA with a 3'-to-5' polarity, yielding deoxynucleoside monophosphates as reaction products. This exonuclease activity was dependent on Mg2+ and inhibited by addition of 5 mM nucleoside monophosphates. This exonuclease activity is intrinsic to the wild-type p53 protein: it copurified with p53 during p53 preparation; only purified wild-type p53, but not identically purified mutant p53 proteins displayed exonuclease activity; the exonuclease activity could be reconstituted from SDS gel-purified and urea-renatured p53 protein and mapped to the core domain of the p53 molecule; and finally, purified p53 protein could be UV-cross-linked to GMP. A p53-intrinsic exonuclease activity should substantially extend our view on the role of p53 as a "guardian of the genome."
从不同来源高度纯化的p53蛋白能够以3'至5'的极性降解DNA，产生脱氧核苷单磷酸作为反应产物。这种核酸外切酶活性依赖于Mg2+，并受到5 mM核苷单磷酸添加的抑制。这种核酸外切酶活性是野生型p53蛋白所固有的：它在p53制备过程中与p53共纯化；只有纯化的野生型p53，而不是同样纯化的突变型p53蛋白显示出核酸外切酶活性；核酸外切酶活性可以从SDS凝胶纯化和尿素复性的p53蛋白中重构，并定位到p53分子的核心结构域；最后，纯化的p53蛋白可以与GMP进行紫外线交联。p53固有的核酸外切酶活性将极大地扩展我们对p53作为“基因组守护者”作用的认识。
