Albor A, Kaku S, Kulesz-Martin M
Department of Experimental Therapeutics, Roswell Park Cancer Institute, Buffalo, New York 14263, USA.
Cancer Res. 1998 May 15;58(10):2091-4.
p53-interacting proteins from mouse epidermal cells and human myelogenous leukemia cells were isolated by affinity chromatography using glutathione S-transferase (GST)-p53 fusion proteins. One of these proteins was topoisomerase I, whose interaction with p53 was recently reported. A carboxyl-terminal fragment containing the last 92 amino acids of p53 (GST-299-390) was sufficient for binding to topoisomerase I. Nanomolar concentrations of either GST-p53 or GST-299-390 enhanced the catalytic activity of purified human topoisomerase I. Purified wild-type human p53 and point mutants Ser-239, Ser-245, and His-273 were equivalent in their enhancement of human topoisomerase I activity. Because topoisomerase I is thought to promote genetic recombination, competence to enhance topoisomerase I catalytic activity coupled with a deficiency in transcriptional activity may be a mechanism for gain of function in mutant p53 proteins.
利用谷胱甘肽S-转移酶（GST）-p53融合蛋白，通过亲和层析法从小鼠表皮细胞和人骨髓性白血病细胞中分离出与p53相互作用的蛋白。其中一种蛋白是拓扑异构酶I，其与p53的相互作用最近已有报道。包含p53最后92个氨基酸的羧基末端片段（GST-299-390）足以与拓扑异构酶I结合。纳摩尔浓度的GST-p53或GST-299-390均可增强纯化的人拓扑异构酶I的催化活性。纯化的野生型人p53以及点突变体Ser-239、Ser-245和His-273在增强人拓扑异构酶I活性方面效果相当。由于拓扑异构酶I被认为可促进基因重组，增强拓扑异构酶I催化活性的能力以及转录活性的缺陷可能是突变型p53蛋白功能获得的一种机制。
