Precursor-directed biosynthesis of 16-membered macrolides by the erythromycin polyketide synthase
Precursor-directed biosynthesis of 16-membered macrolides by the erythromycin polyketide synthase
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DOI：
10.1021/ja004139l
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发表时间：
2001-03-21
影响因子：
15
通讯作者：
Cane, DE
中科院分区：
文献类型：
--
作者：
Kinoshita, K;Williard, PG;Cane, DE
链霉菌CH999/pJRJ2含有一个编码DEBS（KS1度）的质粒，这是一种6-脱氧红素内酯B合成酶的突变形式，在6-脱氧红素内酯B （1,6 - deb）的形成过程中被阻断，而酮合成酶（KS1）结构域的活性位点突变通常催化6-dEB生物合成的第一个聚酮链延伸步骤。（2E,4S,5R）-2,4-二甲基-5-羟基-2-庚酸，n-乙酰半胱胺硫酯(6)是一种天然三酮链延伸中间体的不饱和三酮类似物，在培养的S. coelicolor CH999/pJRJ2中形成了一个16元的大内酯，分离出半晶形式33。octaketide 33的形成表明三酮类底物已经被DEBS模块2处理，就好像它是二酮类类似物一样。通过与S. coelicolor CH999/pJRJ2孵育另外三种不饱和三酮6的类似物，化合物1.8、31和32，从而形成相应的大内酯34、35和36，研究了这种新反应的底物特异性。相比之下，在C-2缺失甲基的不饱和三酮10与S. coelicolor CH999/pJpJ2孵育时，没有产生任何可检测到的大内酯产物。
Streptomyces coelicolor CH999/pJRJ2 harbors a plasmid encoding DEBS(KS1 degrees), a mutant form of 6-deoxyerythronolide B synthase that is blacked in the formation of 6-deoxyerythronolide B (1, 6-dEB) duel to a mutation in the active site of the ketosynthase (KS1) domain that normally-catalyzes the first polyketide chain elongation step of 6-dEB biosynthesis. Administration of (2E,4S,5R)-2,4-dimethyl-5-hydroxy-2-heptenoic acid, N-acetylcysteamine thioester (6) an unsaturated triketide analogue of the natural triketide chain elongation intermediate to cultures-of S. coelicolor CH999/pJRJ2 results in formation-of a 16-membered macrolactone, which is isolated in the hemiketal form 33. The formation of the octaketide 33 indicates that the triketide substrate has been processed by DEBS module 2 as if it were a diketide analogue. The substrate specificity of this novel reaction has been explored by the incubation of three additional analogues of the unsaturated triketide 6, compounds 1.8, 31, and 32, with S. coelicolor CH999/pJRJ2, resulting in the formation of the corresponding macrolactones 34, 35, and 36. By contrast, the unsaturated triketide 10, lacking a methyl group at C-2, did not give rise to any detectable macrolactone product when incubated with S. coelicolor CH999/pJpJ2.