Zhu X, Wang Y, Jin L, Xu X
Institute of Medicinal Biotechnology, Chinese Academy of Medical Science, Beijing.
Chin J Biotechnol. 1991;7(4):241-51.
A 2.4 kb fragment containing the midecamycin polyketide synthase genes (mps) was subcloned from the preliminary clone pCN8B12 out of the genomic library of midecamycin-producing strain S. mycarofaciens 1748, by using the homologous DNA of the actinorhodin polyketide synthase gene (act I) as hybridization probe. This DNA fragment was subcloned onto Streptomyces/E. coli shuttle vector pMHM3. A recombinant plasmid pCG2 was obtained. The transformation of the polyketide synthase deficient mutant of actinorhodin-producing strain, S. colicolor TK17, with pCG2 DNA resulted in the production of an antibacterial compound which was similar neither to actinorhodin nor to midecamycin. The transformation of spiramycin-producing strain S. ambofaciens with pCG2 DNA increased spiramycin production in the fermentation broth. The transformation of the regulatory mutant of daunorubicin-producing strain with pCG2 DNA resulted in the production of epsilon-rhodomycinone verified by TLC and HPLC analyses. The pCG2 DNA also could be functionally expressed in tetracenomycin C-producing strain S. glaucescens. However, it could not be expressed in the blocked mutants of erythromycin-producing strain Saccharopolyspora erythrarea WMH 15,261. These suggest that the pCG2 DNA may complement polyketide synthase gene deficiency or have some regulatory function in certain polyketide antibiotic-producing strains.
以放线紫红素聚酮合酶基因（act I）的同源DNA为杂交探针，从麦迪霉素产生菌弗氏链霉菌1748基因组文库的初步克隆pCN8B12中，亚克隆出一个包含麦迪霉素聚酮合酶基因（mps）的2.4 kb片段。将该DNA片段亚克隆到链霉菌/大肠杆菌穿梭载体pMHM3上，获得重组质粒pCG2。用pCG2 DNA转化放线紫红素产生菌天蓝色链霉菌TK17的聚酮合酶缺陷型突变体，产生了一种既不同于放线紫红素也不同于麦迪霉素的抗菌化合物。用pCG2 DNA转化螺旋霉素产生菌浅青紫链霉菌，可提高发酵液中螺旋霉素的产量。用pCG2 DNA转化柔红霉素产生菌的调节突变体，经薄层层析（TLC）和高效液相色谱（HPLC）分析验证，产生了ε-红霉酮。pCG2 DNA在四环素霉素C产生菌青灰链霉菌中也能进行功能表达。然而，它在红霉素产生菌糖多孢红霉菌WMH 15261的阻断突变体中不能表达。这些结果表明，pCG2 DNA可能互补聚酮合酶基因缺陷，或在某些聚酮类抗生素产生菌中具有一定的调节功能。
