Identification of csypyrone B1 as the novel product of Aspergillus oryzae type III polyketide synthase CsyB.
Identification of csypyrone B1 as the novel product of Aspergillus oryzae type III polyketide synthase CsyB.
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DOI：
10.1016/j.bmc.2010.04.058
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发表时间：
2010-06
影响因子：
3.5
通讯作者：
Y. Seshime;P. R. Juvvadi;K. Kitamoto;Y. Ebizuka;I. Fujii
中科院分区：
文献类型：
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作者：
Y. Seshime;P. R. Juvvadi;K. Kitamoto;Y. Ebizuka;I. Fujii
csyA、csyB、csyC和csyD是微生物中一个新的III型聚酮合成酶（pks）超家族，在工业上重要的丝状真菌米曲霉（Aspergillus oryzae）的基因组中被发现。虽然csyA、csyC和csyD基因的同源物存在于一个密切相关的物种——黄曲霉中，但csyB基因是米曲霉所特有的。为了确定其功能，我们在α-淀粉酶启动子的控制下，在稻瘟病菌中过表达csyB基因。3-（3-乙酰基-4-羟基-2-氧- 2h -吡喃-6-基）丙烷酸，命名为csyrone B1，经鉴定为CsyB产物。13c标记乙酸的饲养实验表明，5个乙酸单元被纳入赛吡酮B1。提出了环吡啶酮B1生物合成的两种可能机制：(1)琥珀酰辅酶a与三个乙酰/丙二酰辅酶a缩合，随后发生环吡啶环环化；(2)丁基辅酶a与三个乙酰基/丙二醇辅酶a缩合，并进行吡酮环环化和侧链氧化反应。
As a novel superfamily of type III polyketide synthases (PKSs) in microbes, four genes, csyA, csyB, csyC, and csyD, were found in the genome of Aspergillus oryzae, an industrially important filamentous fungus. Although orthologs of csyA, csyC, and csyD genes are present in a closely related species, Aspergillus flavus, csyB gene is unique to A. oryzae. To identify its function, we carried out overexpression of csyB gene under the control of α-amylase promoter in A. oryzae. 3-(3-Acetyl-4-hydroxy-2-oxo-2H-pyran-6-yl)propanoic acid, named csypyrone B1, was identified as a CsyB product. Feeding experiments of13C-labeled acetate indicated that five acetate units were incorporated into csypyrone B1. Two possible mechanisms are proposed for the biosynthesis of cycpyrone B1: (1) condensation of succinyl-CoA with three acetyl/malonyl-CoAs, and the following pyrone ring cyclization; (2) condensation of butyryl-CoA with three acetyl/malonyl-CoAs, and the following pyrone ring cyclization and side-chain oxidation.