N -Myristoyltransferase (NMT) is an emerging therapeutic target that catalyzes the attachment of myristate to the N terminus of an acceptor protein. We have developed a medium-throughput assay for screening potential small molecule inhibitors of human NMT-1 consisting of recombinant enzyme, biotinylated peptide substrate, and [3H]myristoyl-CoA. Approximately 16,000 diverse compounds have been evaluated, and significant inhibition of NMT was found with 0.8% of the compounds. From these hits, we have identified the cyclohexyl-octahydropyrrolo[1,2- a ]pyrazine (COPP) chemotype as inhibitory toward human NMT-1. Thirty-two compounds containing this substructure inhibited NMT-1, with IC50 values ranging from 6 μM to millimolar concentrations, and a quantitative structure-activity relationship equation ( r 2 = 0.72) was derived for the series. The most potent inhibitor (24, containing 9-ethyl-9 H -carbazole) demonstrated competitive inhibition for the peptide-binding site of NMT-1 and noncompetitive inhibition for the myristoyl-CoA site. Computational docking studies using the crystal structure of the highly homologous yeast NMT confirmed that 24 binds with excellent complementarity to the peptide-binding site of the enzyme. To evaluate the ability of 24 to inhibit NMT activity in intact cells, monkey CV-1 cells expressing an N -myristoylated green fluorescent protein (GFP) fusion protein were treated with a known NMT inhibitor or with 24. Each compound caused the redistribution of GFP from the plasma membrane to the cytosol. Furthermore, 24 inhibits cancer cell proliferation at doses similar to those that inhibit protein myristoylation. Overall, these studies establish an efficient assay for screening for inhibitors of human NMT and identify a novel family of inhibitors that compete at the peptide-binding site and have activity in intact cells.
                                    N -肉豆蔻酰基转移酶(N
MT)是一种新兴的治疗靶点,它能催化
肉豆蔻酸盐附着到受体蛋白的 N 端。我们开发了一种中等通量检测方法,用于筛选人类 N
MT-1 的潜在小分子
抑制剂,该方法由
重组酶、
生物素化肽底物和 [3H]myristoyl-CoA 组成。评估了约 16,000 种不同的化合物,发现 0.8% 的化合物对 N
MT 有显著抑制作用。从这些化合物中,我们发现环己基-八氢
吡咯并[1,2- a ]
吡嗪(C
OPP)
化学型对人类 N
MT-1 有抑制作用。含有这种亚结构的 32 种化合物对 N
MT-1 具有抑制作用,IC50 值从 6 μM 到毫摩尔浓度不等,并得出了该系列化合物的定量结构-活性关系式(r 2 = 0.72)。最有效的
抑制剂(24,含有 9-ethyl-9 H -carbazole)对 N
MT-1 的肽结合位点具有竞争性抑制作用,而对肉豆蔻酰-CoA 位点具有非竞争性抑制作用。利用高度同源的酵母 N
MT 晶体结构进行的计算对接研究证实,24 与该酶的肽结合位点具有极佳的互补性。为了评估 24 在完整细胞中抑制 N
MT 活性的能力,用已知的 N
MT 抑制剂或 24 处理表达 N -肉豆蔻酰化绿色荧光蛋白(GFP)融合蛋白的猴 CV-1 细胞。每种化合物都会导致 GFP 从质膜重新分布到细胞膜。此外,24抑制癌细胞增殖的剂量与抑制蛋白质肉豆蔻酰化的剂量相似。总之,这些研究为筛选人类 N
MT 抑制剂建立了一种有效的检测方法,并确定了在
多肽结合位点上竞争并在完整细胞中具有活性的新型
抑制剂家族。