An iterative type I polyketide synthase PKSN catalyzes synthesis of the decaketide alternapyrone with regio-specific octa-methylation
An iterative type I polyketide synthase PKSN catalyzes synthesis of the decaketide alternapyrone with regio-specific octa-methylation
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DOI：
10.1016/j.chembiol.2005.09.015
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发表时间：
2005-12-01
影响因子：
--
通讯作者：
Ebizuka, Y
中科院分区：
文献类型：
--
作者：
Fujii, I;Yoshida, N;Ebizuka, Y
从番茄和马铃薯早疫病病原菌Alternaria solani中克隆了一个含有5个基因的生物合成基因簇ALT1-5。同源性搜索表明，alt1、2和3基因编码细胞色素P450，alt4基因编码依赖于FAD的加氧酶/氧化酶。Alt5基因编码一个多酮合成酶(PKS)，命名为PKSN，是一个带有C-甲基转移酶结构域的I型复合体。为了鉴定PKSN的功能，在α-淀粉酶启动子的作用下，将alt5基因导入真菌寄主米曲霉。转化子产生了一种聚酮化合物，命名为交替吡喃酮，其结构为3，5-dimethyl-4-hydroxy6-(1，3，5，7，11，13-hexamethyl-3，5，1-1-十五三烯基)吡喃-2-酮。标记实验证实，交链孢子酮是一种十烷基化合物，除第三个单元外，其余每个C-2单元上都有甲硫氨酸的八甲基化。
A biosynthetic gene cluster containing five genes, alt1-5, was cloned from Alternaria solani, a causal fungus of early blight disease to tomato and potato. Homology searching indicated that the altl, 2, and 3 genes code for cytochrome P450s and the alt4 gene for a FAD-dependent oxygenase/oxidase. The alt5 gene encodes a polyketide synthase (PKS), named PKSN, that was found to be an iterative type I complex reduced-type PKS with a C-methyltransferase domain. To identify the PKSN function, the alt5 gene was introduced into the fungal host Aspergillus oryzae under an alpha-amylase promoter. The transformant produced a polyketide compound, named alternapyrone, whose structure is shown to be 3,5-dimethyl-4-hydroxy6-(1,3,5,7,11,13-hexamethyl-3,5,1 1-pentadecatrienyl)pyran-2-one. Labeling experiments confirmed that alternapyrone is a decalketide with octa-methylation from methionine on every C-2 unit except the third unit.