Biosynthesis of Aliphatic Polyketides by Type III Polyketide Synthase and Methyltransferase in Bacillus subtilis
Biosynthesis of Aliphatic Polyketides by Type III Polyketide Synthase and Methyltransferase in Bacillus subtilis
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DOI：
10.1128/jb.00407-09
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发表时间：
2009-08-01
影响因子：
3.2
通讯作者：
Horinouchi, Sueharu
中科院分区：
文献类型：
--
作者：
Nakano, Chiaki;Ozawa, Hiroki;Horinouchi, Sueharu
III型聚酮合成酶（Type III polyketide synthases, pks）在植物、真菌和细菌中合成多种芳香聚酮。细菌基因组计划预测可能的III型PKS基因分布在各种革兰氏阳性和阴性细菌中。革兰氏阳性模型微生物枯草芽孢杆菌含有bcsA-ypbQ操纵子，其似乎分别编码III型PKS和甲基转移酶。在这里，我们报道了bcsA（更名为bpsA，为芽孢杆菌pyrone合成酶，基于其功能）和ypbQ的特性，它们参与脂肪族聚酮的生物合成。体内分析表明，BpsA是一种III型PKS，以长链脂肪酸酰基辅酶a （CoA）硫酯为起始底物，丙二酰辅酶a为扩展底物催化合成三酮吡啶酮，YpbQ是一种甲基转移酶，作用于三酮吡啶酮生成烷基吡啶酮甲基醚。YpbQ因此被命名为BpsB，因为它与BpsA具有功能上的相关性。用组氨酸标记的BpsA体外分析表明，它使用广泛的起始底物，不仅可以产生三酮吡咯，还可以产生四酮吡咯和烷基间苯二酚。尽管脂肪族聚酮被认为定位于膜中，并在调节膜的硬度和性质方面发挥一定作用，但对于含有bpssa - bpsb操纵子完全缺失的枯草芽孢杆菌突变体，没有观察到可检测到的表型变化。
Type III polyketide synthases (PKSs) synthesize a variety of aromatic polyketides in plants, fungi, and bacteria. The bacterial genome projects predicted that probable type III PKS genes are distributed in a wide variety of gram-positive and -negative bacteria. The gram-positive model microorganism Bacillus subtilis contained the bcsA-ypbQ operon, which appeared to encode a type III PKS and a methyltransferase, respectively. Here, we report the characterization of bcsA (renamed bpsA, for Bacillus pyrone synthase, on the basis of its function) and ypbQ, which are involved in the biosynthesis of aliphatic polyketides. In vivo analysis demonstrated that BpsA was a type III PKS catalyzing the synthesis of triketide pyrones from long-chain fatty acyl-coenzyme A (CoA) thioesters as starter substrates and malonyl-CoA as an extender substrate, and YpbQ was a methyltransferase acting on the triketide pyrones to yield alkylpyrone methyl ethers. YpbQ thus was named BpsB because of its functional relatedness to BpsA. In vitro analysis with histidine-tagged BpsA revealed that it used broad starter substrates and produced not only triketide pyrones but also tetraketide pyrones and alkylresorcinols. Although the aliphatic polyketides were expected to localize in the membrane and play some role in modulating the rigidity and properties of the membrane, no detectable phenotypic changes were observed for a B. subtilis mutant containing a whole deletion of the bpsA-bpsB operon.