結(jié)構(gòu)復(fù)雜的天然產(chǎn)物歷來(lái)是抗腫瘤藥物的重要來(lái)源,。FR901464是假單孢菌產(chǎn)生的,、結(jié)構(gòu)獨(dú)特且具有全新作用機(jī)制（作用于mRNA剪接體系的SF3b復(fù)合物）的高活性抗腫瘤天然產(chǎn)物（對(duì)多種人癌細(xì)胞體外的IC50為0.6-3.4 nM），近年來(lái)引起了有機(jī)合成,、藥物化學(xué)及化學(xué)生物學(xué)等多方面的關(guān)注,。
中科院上海有機(jī)化學(xué)研究所生命有機(jī)化學(xué)國(guó)家重點(diǎn)實(shí)驗(yàn)室的科研人員經(jīng)過(guò)三年多的努力，采用PCR克隆特異的羥基-甲基戊二酰輔酶A合成酶(HCS)基因的方法,，從假單孢菌sp. No. 2663中克隆了完整的FR901464生物合成基因簇,。該基因簇包含20個(gè)基因,，編碼5個(gè)“AT-less”聚酮合成酶(PKS)，1個(gè)雜合的聚酮/非核糖體聚肽合成酶(PKS/NRPS),，1個(gè)非核糖體聚肽合成酶(NRPS),，3個(gè)獨(dú)立的酰基轉(zhuǎn)移酶(AT),，4個(gè)聚酮骨架β-烷基化相關(guān)蛋白,，4個(gè)后修飾酶，2個(gè)調(diào)控蛋白,。
通過(guò)體內(nèi)基因敲除和體外生化實(shí)驗(yàn)相結(jié)合,，研究人員初步闡明了FR901464獨(dú)特的生物合成途徑：采用高度雜合的“AT-less”PKS-NRPS-HCS三元體系，以甘油作為PKS的起始單元,、Baeyer-Villiger氧化解離聚酮鏈,。
該研究揭示了自然界聚酮天然產(chǎn)物生物合成中復(fù)雜多樣的生物合成機(jī)理，為進(jìn)一步發(fā)現(xiàn)新的酶催化反應(yīng)并通過(guò)對(duì)其生物合成基因的調(diào)控產(chǎn)生結(jié)構(gòu)類(lèi)似物創(chuàng)造了條件,。
該研究工作得到國(guó)家自然科學(xué)基金委,、科技部、中國(guó)科學(xué)院和上海市科委的資助,，部分研究結(jié)果發(fā)表于J. Am. Chem. Soc. （2011, 133, 2452-2462）,。（生物谷Bioon.com）
生物谷推薦原文出處：
J. Am. Chem. Soc., 2011, 133 (8), pp 2452–2462 DOI: 10.1021/ja105649g
Cloning and Elucidation of the FR901464 Gene Cluster Revealing a Complex Acyltransferase-less Polyketide Synthase Using Glycerate as Starter Units
Feng Zhang, Hai-Yan He, Man-Cheng Tang, Yu-Min Tang, Qiang Zhou, and Gong-Li Tang*
FR901464, an antitumor natural product, represents a new class of potent anticancer small molecules targeting spliceosome and inhibiting both splicing and nuclear retention of pre-mRNA. Herein we describe the biosynthetic gene cluster of FR901464, identified by degenerate primer PCR amplification of a gene encoding the 3-hydroxy-3-methylglutaryl-CoA synthase (HCS) postulated to be involved in the biosynthesis of a β-branched polyketide from Pseudomonas sp. No. 2663. This cluster consists of twenty open reading frames (ORFs) and was localized to 93-kb DNA segment, and its involvement in FR901464 biosynthesis was confirmed by gene inactivation and complementation. FR901464 is biosynthesized by a hybrid polyketide synthase (PKS)/nonribosomal peptide synthetase (NRPS), HCS, and acyltransferases (AT)-less system. The PKS/NRPS modules feature unusual domain organization including multiple domain redundancy, inactivation, and tandem. Biochemical characterization of a glyceryl transferase and an acyl carrier protein (ACP) in the start module revealed that it incorporates D-1,3-bisphosphoglycerate, which is dephosphorylated and transferred to ACP as the starter unit. Furthermore, an oxidative Baeyer?Villiger reaction followed by chain release was postulated to form a pyran moiety. On the basis of in silico analysis and genetic and biochemical evidances, a biosynthetic pathway for FR901464 was proposed, which sets the stage to further investigate the complex PKS biochemically and engineer the biosynthetic machinery for the production of novel analogues.
