MACCHESS CONSORTIUM FOR XRAY DETECTORS IN MACROMOLECULAR CRYSTALLOGRAPHY

FHIT基因座的遗传缺失是最常见的， 最早已知的肺癌和其他几种常见的 人类癌症 Fhit蛋白切割AppPA，一种二核苷酸， 底物，转化为AMP加ADP，但我们已经表明， 切割AppPA酶与肿瘤抑制因子无关 功能 相反，生物化学和遗传学证据表明， 作为酶-底物复合物的肿瘤抑制信号。 到 明确了Fhit蛋白信号传导的结构基础， 使不可水解的AppPA类似物与野生型Fhit共结晶， 突变的Fhit蛋白在AppPA水解中有缺陷。 作为 晶体为六方针状，a ~270
像元长度，数据 需要在同步加速器源处收集。 晶体 Fhit底物类似物复合物的结构揭示了一种新的模式， 蛋白质调节，其与由以下调节的蛋白质具有相似性 核苷酸结合和受蛋白质调节的蛋白质 磷酸化 如对于GTP酶所见， 底物络合物与产物络合物完全不同。 然而，与GTP酶的情况不同， 复杂性在很大程度上没有改变。 相反，Fhit提出了两个ApppA类似物 在蛋白质的“顶部”表面上， 充电槽 事实上，Fhit-AppPA复合物是“磷酸化的”。 六种表面磷酸盐 因此，晶体结构分析表明 Fhit-底物复合物是Fhit的活性信号形式。 4. C. H.C.布伦纳Pace，P.N. Garrison，A.K.罗宾逊，A. R sler，X. Liu，G.M. Blackburn，C.M. Croce，K.许布纳公司巴恩斯， “模拟活性物质的复合物的纯化和结晶 脆性组氨酸三联体蛋白的状态，”蛋白质工程，v. 10，pp. 1461-1463（1997）。 H.C. Pace，P.N. Garrison，A.K.罗宾逊， L.D.巴恩斯，A. Draganescu，A. R sler，G.M.布莱克本，Z。西普拉什维利， C.M. Croce，K. Huebner & C.布伦纳，“遗传，生物化学和 基质模拟复合物的晶体学定义 脆性组氨酸三联体蛋白作为Fhit的活性信号形式，” Proc. Natl. Acad. 科学，第95页。 5484-5489（1998年）。

Genetic deletions at the FHIT locus are the most frequent and the earliest known genetic change in lung cancer and several other common human cancers. The Fhit protein cleaves ApppA, a dinucleotide substrate, into AMP plus ADP, but we have shown that the ability of the enzyme to cleave ApppA does not correlate with tumor suppressor function. Rather, biochemical and genetic evidence indicate that Fhit signals for tumor suppression as an enzyme-substrate complex. To define the structural basis of signaling by Fhit protein, we co-crystallized a nonhydrolyzable ApppA analog with wild-type Fhit and with a mutant Fhit protein that has a defect in ApppA hydrolysis. As these crystals were hexagonal needles with a ~270
cell length, data collection at a synchrotron source was required. The crystal structures of Fhit-substrate analog complexes revealed a novel mode of protein regulation which bears similarities with proteins regulated by nucleotide-binding and with proteins regulated by protein phosphorylation. As has been seen for GTPases, the structure of the substrate complex is quite different from the product complex. However, unlike the case of GTPases, the protein portion of the complex is largely unchanged. Rather, Fhit presents two ApppA analogs on the "top" surface of the protein in place of a deep, positively charged groove. Fhit-ApppA complexes are, in fact, "phosphorylated" by six surface phosphates. Thus, crystal structure analysis suggests that Fhit-substrate complexes are the active, signaling form of Fhit. 4. C. Brenner, H.C. Pace, P.N. Garrison, A.K. Robinson, A. R sler, X. Liu, G.M. Blackburn, C.M. Croce, K. Huebner & L.D. Barnes, "Purification and Crystallization of Complexes Modeling the Active State of the Fragile Histidine Triad Protein," Protein Engineering, v. 10, pp. 1461-1463 (1997). H.C. Pace, P.N. Garrison, A.K. Robinson, L.D. Barnes, A. Draganescu, A. R sler, G.M. Blackburn, Z. Siprashvili, C.M. Croce, K. Huebner & C. Brenner, "Genetic, Biochemical and Crystallographic Definition of a Substrate Analog Complex with the Fragile Histidine Triad Protein as the Active Signaling Form of Fhit," Proc. Natl. Acad. Sci., v. 95, pp. 5484-5489 (1998).