Cloning of the gene cluster responsible for biosynthesis of KS-505a (longestin), a unique tetraterpenoid
Cloning of the gene cluster responsible for biosynthesis of KS-505a (longestin), a unique tetraterpenoid
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DOI：
10.1271/bbb.70477
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发表时间：
2007-12-01
影响因子：
1.6
通讯作者：
Dairi, Tohru
中科院分区：
文献类型：
--
作者：
Hayashi, Yutaka;Onaka, Hiroyasu;Dairi, Tohru
KS-505 a（longestin）由Streptomyces argenteolus产生，具有由四萜（C40）骨架组成的独特结构，2-O-甲基葡萄糖醛酸和邻琥珀酰苯甲酸酯部分连接到该骨架上。它是一种新型钙调蛋白依赖性环核苷酸磷酸二酯酶抑制剂，是一种有效的抗健忘症药物的代表。作为了解这种独特的和药学上有用的化合物的生物合成机制的第一步，我们克隆了KS 505 a生物合成基因簇。首先，我们寻找编码八异戊二烯二磷酸的基因，通过PCR得到C40前体，并获得四个候选基因。其中，一个被证实具有预期的酶活性的重组酶测定。根据对该基因侧翼区的分析，推测KS-505 a生物合成基因簇由24个ORF组成，可能存在于28-kb的DNA片段上。还采用基因破坏实验来证实簇确实参与KS-505 a生物合成。这被认为是第一个详细的环化四萜类化合物的基因簇的报告。
KS-505a (longestin), produced by Streptomyces argenteolus, has a unique structure that consists of a tetraterpene (C40) skeleton, to which a 2-O-methylglucuronic acid and an o-succinyl benzoate moiety are attached. It is a novel inhibitor of calmodulin-dependent cyclic-nucleotide phosphodiesterase, which is representative of a potent anti-amnesia drug. As a first step to understanding the biosynthetic machinery of this unique and pharmaceutically useful compound, we cloned a KS505a biosynthetic gene cluster. First we searched for a gene encoding octaprenyl diphosphates, which yielded a C40 precursor by PCR, and four candidate genes were obtained. Among these, one was confirmed to have the expected enzyme activity by recombinant enzyme assay. On the basis of an analysis of the flanking regions of the gene, a putative KS-505a biosynthetic gene cluster consisting of 24 ORFs was judged perhaps to be present on a 28-kb DNA fragment. A gene disruption experiment was also employed to confirm that the cluster indeed participated in KS-505a biosynthesis. This is believed to be the first report detailing the gene cluster of a cyclized tetraterpenoid.