Stereospecificity of ketoreductase domains 1 and 2 of the tylactone modular polyketide synthase.
Stereospecificity of ketoreductase domains 1 and 2 of the tylactone modular polyketide synthase.
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DOI：
10.1021/ja804453p
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发表时间：
2008-09-03
影响因子：
15
通讯作者：
Cane, David E.
中科院分区：
文献类型：
--
作者：
Castonguay, Roselyne;Valenzano, Chiara R.;Chen, Alice Y.;Keatinge-Clay, Adrian;Khosla, Chaitan;Cane, David E.
泰内酯合酶（TYLS）是一种模块化聚酮合酶，催化形成泰内酯（1），泰内酯是大环内酯类抗生素泰乐菌素的母体糖苷配基前体。TYLS模块1和2分别负责产生抗二酮化合物和三酮化合物中间体，各自结合至酰基载体蛋白（ACP）结构域。每个模块含有酮还原酶（KR）结构域。TYLS KR 1和TYLS KR 2的立体特异性通过在顺式-（2S，3R）-2-甲基-3-羟基戊酸的N-乙酰基半胱胺硫酯（6）、甲基丙二酰-CoA，和NADPH，导致仅形成ACP结合的（2 R，3R，4S，5 R）-2，4-甲基-3，5-二羟基庚酰基三酮化合物，如通过衍生的三酮化合物内酯7的TMS醚的GC-MS分析所确定的。因此，TYLS KR 1和KR 2均催化2-甲基-3-酮酰基-ACP底物从表面的立体特异性还原，对（2 R）-甲基（D）非对映异构体的还原具有特异性。因此，由TYLS模块2的脱氢酶（DH）结构域催化以得到不饱和的（2 E，4S，5 R）-2，4-二甲基-5-羟基庚-2-烯酰基-ACP 2的脱水是水的顺式消除。
Tylactone synthase (TYLS) is a modular polyketide synthase that catalyzes the formation of tylactone (1), the parent aglycone precursor of the macrolide antibiotic tylosin. TYLS modules 1 and 2 are responsible for the generation of anti-diketide and triketide intermediates, respectively, each bound to an acyl carrier protein (ACP) domain. Each module harbors a ketoreductase (KR) domain. The stereospecificity of TYLS KR1 and TYLS KR2 has been determined by incubating each of the recombinant ketoreductase domains with reconstituted ketosynthase—acyltransferase [KS][AT] and ACP domains from the 6-deoxyerythronolide B synthase (DEBS) in the presence of the N-acetylcysteamine thioester of syn-(2S,3R)-2-methyl-3-hydroxypentanoate (6), methylmalonyl-CoA, and NADPH resulting in the exclusive formation of the ACP-bound (2R,3R,4S,5R)-2,4-methyl-3,5-dihydroxyhepanoyl triketide, as established by GC-MS analysis of the TMS ether of the derived triketide lactone 7. Both TYLS KR1 and KR2 therefore catalyze the stereospecific reduction of the 2-methyl-3-ketoacyl-ACP substrate from the re-face, with specificity for the reduction of the (2R)-methyl (D) diastereomer. The dehydration that is catalyzed by the dehydratase (DH) domains of TYLS module 2 to give the unsaturated (2E,4S,5R)-2,4-dimethyl-5-hydroxyhept-2-enoyl-ACP2 is therefore a syn elimination of water.
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DOI：
10.1039/c39780000193
发表时间：
1978-01-01
影响因子：
--
作者：
SEDGWICK, B;MORRIS, C;FRENCH, SJ
通讯作者：
FRENCH, SJ
影响因子：
15
作者：
CANE, DE;LAMBALOT, RH;OTT, WR
通讯作者：
OTT, WR
影响因子：
3.2
作者：
Caffrey, P
通讯作者：
Caffrey, P
影响因子：
15
作者：
Kao, CM;McPherson, M;Khosla, C
通讯作者：
Khosla, C
影响因子：
5.7
作者：
Keatinge-Clay, AT;Stroud, RM
通讯作者：
Stroud, RM