The identification of bacillaene, the product of the PksX megacomplex in Bacillus subtilis
The identification of bacillaene, the product of the PksX megacomplex in Bacillus subtilis
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DOI：
10.1073/pnas.0610503104
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发表时间：
2007-01-30
影响因子：
11.1
通讯作者：
Clardy, Jon
中科院分区：
文献类型：
--
作者：
Butcher, Rebecca A.;Schroeder, Frank C.;Clardy, Jon
枯草芽孢杆菌中大约80 kb的pksX基因簇编码一种不寻常的杂交多酮/非核糖体肽合成酶，该合成酶与未表征的抗生素杆菌烯的产生有关。这种合成酶的多个拷贝，每个拷贝的大小与核糖体相似，组装成一个单一的细胞器样复合体，其质量为数十到数百兆道尔顿。组装的巨型复合体的资源需求表明，芽胞杆菌素具有重要的生物学作用。通过将差分核磁共振光谱技术与基因操纵的枯草芽孢杆菌菌株相结合，我们能够表征这种不寻常的次生代谢物的结构，这是生物信息学分析无法预测的。我们报道了杆菌烯是一种具有两个酰胺键的线性分子：第一个键将α -羟基羧酸连接到含有共轭己烯的ω -氨基羧酸，第二个键将含己烯的羧酸连接到含有共轭三烯的（ω -1）氨基羧酸。对杆菌烯结构的了解使我们能够对pksX基因簇进行注释，这将有助于研究杆菌烯的生物合成及其在枯草芽孢杆菌中的生物学作用。
The approximate to 80-kb pksX gene cluster in Bacillus subtilis encodes an unusual hybrid polyketide/nonribosomal peptide synthase that has been linked to the production of the uncharacterized antibiotic bacillaene. Multiple copies of this synthase, each similar in size to the ribosome, assemble into a single organelle-like complex with a mass of tens to hundreds of megadaltons. The resource requirements of the assembled megacomplex suggest that bacillaene has an important biological role. By coupling a differential NMR spectroscopic technique with genetically manipulated strains of B. subtilis, we were able to characterize the structure of this unusual secondary metabolite, which could not be predicted by using bioinformatic analysis. We report that bacillaene is a linear molecule with two amide bonds: the first links an alpha-hydroxy carboxylic acid to a omega-amino carboxylic acid containing a conjugated hexaene, and the second links the hexaene-containing carboxylic acid to an (omega-1) amino carboxylic acid containing a conjugated triene. Knowledge of bacillaene's structure has enabled us to annotate the pksX gene cluster and should facilitate the study of bacillaene's biosynthesis as well as its biological role in B. subtilis.