Starter unit specificity directs genome mining of polyketide synthase pathways in fungi
Starter unit specificity directs genome mining of polyketide synthase pathways in fungi
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DOI：
10.1016/j.bioorg.2007.11.002
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发表时间：
2008-02-01
影响因子：
5.1
通讯作者：
Townsend, Craig A.
中科院分区：
文献类型：
--
作者：
Crawford, Jason M.;Vagstad, Anna L.;Townsend, Craig A.
黄曲霉毒素途径聚酮合酶（PKS）的蛋白质数据库的搜索显示推定的PKS在致病真菌粗球孢子菌和球孢子菌posadasii，可能需要与一对脂肪酸合酶（FAS）亚基的生物合成脂肪酸聚酮杂合代谢产物的伙伴关系。在非还原性PKS中发现了一个起始单位：酰基载体蛋白转酰酶（SAT）结构域。该结构域被认为接受来自FAS的脂肪酸产物以引发聚酮化合物合成。我们在大肠杆菌中表达了犬心丝虫SAT结构域，结果表明，与黄曲霉毒素途径PKS不同，该结构域转移辛酰辅酶A的速度比己酰辅酶A快4倍。SAT结构域还形成共价辛酰基中间体，并将该基团转移到独立的ACP结构域。我们的研究结果表明，C immitis/posadasii，人类真菌病原体，包含FAS/PKS簇的功能相似的黄曲霉毒素簇中发现的曲霉属物种。解剖的PKS和体外SAT结构域特异性的测定提供了一种工具，以揭示真菌中越来越多的类似测序途径，并指导阐明它们产生的脂肪酸-聚酮化合物杂合代谢产物。(C)2007年爱思唯尔公司All rights reserved.
Search of the protein database with the aflatoxin pathway polyketide synthase (PKS) revealed putative PKSs in the pathogenic fungi Coccidioides immitis and Coccidioides posadasii that could require partnerships with a pair of fatty acid synthase (FAS) subunits for the biosynthesis of fatty acid-polyketide hybrid metabolites. A starter unit: acyl-carrier protein transacylase (SAT) domain was discovered in the nonreducing PKS. This domain is thought to accept the fatty acid product from the FAS to initiate polyketide synthesis. We expressed the C immitis SAT domain in Escherichia coli and showed that this domain, unlike that from the aflatoxin pathway PKS, transferred octanoyl-CoA four times faster than hexanoyl-CoA. The SAT domain also formed a covalent octanoyl intermediate and transferred this group to a free-standing ACP domain. Our results suggest that C immitis/posadasii, both human fungal pathogens, contain a FAS/PKS cluster with functional similarity to the aflatoxin cluster found in Aspergillus species. Dissection of the PKS and determination of in vitro SAT domain specificity provides a tool to uncover the growing number of similar sequenced pathways in fungi, and to guide elucidation of the fatty acid-polyketide hybrid metabolites that they produce. (C) 2007 Elsevier Inc. All rights reserved.