Pojer Florence, Li Shu-Ming, Heide Lutz
Eberhard-Karls-Universität Tübingen, Pharmazeutische Biologie, Auf der Morgenstelle 8, D-72076 Tübingen, Germany1.
Microbiology (Reading). 2002 Dec;148(Pt 12):3901-3911. doi: 10.1099/00221287-148-12-3901.
The biosynthetic gene cluster of the aminocoumarin antibiotic clorobiocin was cloned by screening of a cosmid library of Streptomyces roseochromogenes DS 12.976 with two heterologous probes from the novobiocin biosynthetic gene cluster. Sequence analysis revealed 27 ORFs with striking similarity to the biosynthetic gene clusters of novobiocin and coumermycin A(1). Inactivation of a putative aldolase gene, cloR, by in-frame deletion led to the abolishment of the production of clorobiocin. Feeding of the mutant with 3-dimethylallyl-4-hydroxybenzoic acid (Ring A of clorobiocin) restored clorobiocin production. Here, it is suggested that the formation of Ring A of clorobiocin may proceed via a retro-aldol reaction catalysed by CloR, i.e. by a mechanism different from the previously elucidated benzoic acid biosynthetic pathway in Streptomyces maritimus. A comparison of the gene clusters for clorobiocin, novobiocin and coumermycin A(1) showed that the structural differences between the three antibiotics were reflected remarkably well by differences in the organization of their respective biosynthetic gene clusters.
通过用来自新生霉素生物合成基因簇的两个异源探针筛选玫瑰色链霉菌DS 12.976的黏粒文库，克隆了氨基香豆素抗生素氯新生霉素的生物合成基因簇。序列分析揭示了27个开放阅读框，它们与新生霉素和香豆霉素A（1）的生物合成基因簇具有显著相似性。通过框内缺失使推定的醛缩酶基因cloR失活，导致氯新生霉素的产生被消除。用3-二甲基烯丙基-4-羟基苯甲酸（氯新生霉素的A环）喂养突变体可恢复氯新生霉素的产生。在此，表明氯新生霉素A环的形成可能通过由CloR催化的逆醛缩反应进行，即通过一种不同于先前阐明的海产链霉菌中苯甲酸生物合成途径的机制。氯新生霉素、新生霉素和香豆霉素A（1）的基因簇比较表明，这三种抗生素之间的结构差异通过它们各自生物合成基因簇组织的差异得到了很好的反映。
