羊毛硫抗生素雷可肽同源基因簇的异源表达

高杰氏链霉菌中含有新型羊毛硫抗生素雷可肽(lexapeptide)的同源基因簇lxm2,为探索该基因簇相应的产物,将包含lxm2的细菌人工染色体转到变铅青链霉菌中进行异源表达,证实其可以产生雷可肽;同时还获得另一个新次级代谢产物,基因敲除实验表明此化合物的合成也与lxm2相关。通过色谱技术对新化合物进行分离纯化,结合核磁共振谱、高分辨质谱和二级质谱确定其结构为具有多重修饰的线性六肽,与雷可肽的N-端六氨基酸序列相同,命名为Lxm-N-六肽,该化合物没有检测到抗菌活性。

Heterologous expression of lantibiotic lexapeptide biosynthetic gene cluster homologue

Lantibiotics attract extensive attention in the field of discovery and development of antibiotics due to its special action mode and barely observed drug-resistant mutation after being applied for decades. Lexapeptide is a type V lantibiotic recently uncovered via a functional genome mining approach (LEXAS) and has strong antibacterial activity against Gram positive bacteria including MRSA and MRSE. A gene cluster (lxm2) similar to the lexapeptide biosynthetic gene cluster was identified through screening the Streptomyces galtieri genomic DNA bacterial artificial chromosome (BAC) library via LEXAS. The BAC clone carrying lxm2 was introduced into Streptomyces lividians for heterologous expression,leading to the production of lexapeptide and a novel peak in HPLC. The production of lexapeptide and the new peak was disappeared when the lxm2 gene cluster was removed from the BAC clone. Based on NMR spectrometry and high resolution mass spectrometry,the structure of the new compound was identified to be a highly modified linear hexapeptide with sequence identical to the N-terminal six amino acids of lexapeptide,thus Lxm-N-hexapeptide was given as its name. The Lxm-N-hexapeptide did not exhibit antibacterial activity.