Streptomyces hormones and corresponding receptors in antibiotic producing industrial Streptomyces species

链霉菌是革兰氏阳性土壤细菌，其特征是能够产生多种有用的次生代谢产物，以及其复杂的生活史，包括气生菌丝和孢子的形成。已知这两种特征表型相互关联，在一些链霉菌中发现了称为γ-丁内酯自体调节剂的低分子化合物来调节这两种表型。然而，随着链霉菌菌株用于工业规模的抗生素生产，对于调节抗生素生产的内在激素和/或相应的受体蛋白的性质尚不清楚。为了研究自体调节子在工业链霉菌中的可能参与，我们使用了产生恩拉霉素的真菌链霉菌、产生大蒜素的吸湿链霉菌、产生放线菌素的罗氏链霉菌、产生放线菌素的白色链霉菌、产生放线菌素的抗生素链霉菌和链状链球菌、产生纤维抑素的灰色链霉菌、产生红霉素的眼部糖多孢菌、产生鲍霉素的三角链霉菌和产生丝裂霉素的莱文氏链霉菌。根据几种自身调节受体蛋白之间的保守氨基酸序列，设计了聚合酶链式反应(PCR)引物。另外，从受体基因旁边经常存在的Barx型基因出发，设计了另外一套聚合酶链式反应引物。利用这些引物，在上述6个菌株中鉴定出受体同源物和/或Barx同源物。从三角链霉菌中克隆了7个KBP基因组片段，DNA测序表明存在与受体和barX.4同源的基因。推导的受体同源氨基酸序列与IM-2特异性受体FARa有很高的同源性，提示三角链霉菌可能具有IM-2型自身调节因子。

Streptomycetes are Gram-positive soil bacteria characterized by their ability to produce numerous kinds of useful secondary metabolites as well as by their complex life cycle including the formation of aerial mycelia and spores. The two characteristic phenotypes have been know to link each other, and low-molecular-weight compounds called γ-butyrolactone autoregulators have been found in some Streptomyces species to regulate the two phenotypes. However, with the Streptomyces strains used for antibiotic production in industrial scale, nothing has been know on the nature of the intrinsic hormones and/or corresponding receptor proteins to regulate the antibiotic production.1. To survey the possible involvement of autoregulators in industrial Streptomyces strains, we used S. fungicidicus which produces enramycin, S. hygroscopicus which produces maridomycin, S. rochei which produces lancacidin, S. albulus which produces cycloheximide, S. antibioticus and S. catenulae which produce actinomycin, S. albogriseolus which produces fibrostatin, Saccharopolyspora eythrae which produces erythromycin, S. triangulatus which produces baumycin, and S. lavendulae which produces mitomycin.2. From the conserved amino acid sequences among several autoregulator receptor proteins, PCR primers were designed. Also, from the barX-type genes which often exist just beside the receptor genes, other set of PCR primers were designed.3. Using these primers, receptor homologs and/or barX homologs were identified in six of the above strains. Seven kbp genomic fragment was cloned from S. triangulatus, and DNA sequencing revealed the presence of genes homologous to receptor and barX.4. The deduced amino acid sequence of the receptor homolog indicated the high homology to IM-2 specific receptor FarA, indicating that S. triangulatus should possesses IM-2 type autoregulator.