Stutzman-Engwall K J, Otten S L, Hutchinson C R
School of Pharmacy, University of Wisconsin, Madison 53706.
J Bacteriol. 1992 Jan;174(1):144-54. doi: 10.1128/jb.174.1.144-154.1992.
Two DNA segments, dnrR1 and dnrR2, from the Streptomyces peucetius ATCC 29050 genome were identified by their ability to stimulate secondary metabolite production and resistance. When introduced into the wild-type ATCC 29050 strain, the 2.0-kb dnrR1 segment caused a 10-fold overproduction of epsilon-rhodomycinone, a key intermediate of daunorubicin biosynthesis, whereas the 1.9-kb dnrR2 segment increased production of both epsilon-rhodomycinone and daunorubicin 10- and 2-fold, respectively. In addition, the dnrR2 segment restored high-level daunorubicin resistance to strain H6101, a daunorubicin-sensitive mutant of S. peucetius subsp. caesius ATCC 27952. Analysis of the sequence of the dnrR1 fragment revealed the presence of two closely situated open reading frames, dnrI and dnrJ, whose deduced products exhibit high similarity to the products of several other Streptomyces genes that have been implicated in the regulation of secondary metabolism. Insertional inactivation of dnrI in the ATCC 29050 strain with the Tn5 kanamycin resistance gene abolished epsilon-rhodomycinone and daunorubicin production and markedly decreased resistance to daunorubicin. Sequence comparison between the products of dnrIJ and the products of the Streptomyces coelicolor actII-orf4, afsR, and redD-orf1 genes and of the Streptomyces griseus strS, the Saccharopolyspora erythraea eryC1, and the Bacillus stearothermophilus degT genes reveals two families of putative regulatory genes. The members of the DegT, DnrJ, EryC1, and StrS family exhibit some of the features characteristic of the protein kinase (sensor) component of two-component regulatory systems from other bacteria (even though none of the sequences of these four proteins show a significant overall or regional similarity to such protein kinases) and have a consensus helix-turn-helix motif typical of DNA binding proteins. A helix-turn-helix motif is also present in two of the proteins of the other family, AfsR and RedD-Orf1. Both sets of Streptomyces proteins are likely to be trans-acting factors involved in regulating secondary metabolism.
从变铅青链霉菌ATCC 29050基因组中鉴定出两个DNA片段dnrR1和dnrR2，它们具有刺激次级代谢产物产生和抗性的能力。当将2.0 kb的dnrR1片段导入野生型ATCC 29050菌株时，它导致柔红霉素生物合成的关键中间体ε-红霉酮产量增加10倍，而1.9 kb的dnrR2片段分别使ε-红霉酮和柔红霉素的产量增加10倍和2倍。此外，dnrR2片段恢复了对变铅青链霉菌亚种caesius ATCC 27952的柔红霉素敏感突变体H6101的高水平柔红霉素抗性。对dnrR1片段序列的分析揭示了两个紧密相邻的开放阅读框dnrI和dnrJ，其推导产物与其他一些参与次级代谢调控的链霉菌基因的产物具有高度相似性。用Tn5卡那霉素抗性基因使ATCC 29050菌株中的dnrI插入失活，消除了ε-红霉酮和柔红霉素的产生，并显著降低了对柔红霉素的抗性。dnrIJ产物与天蓝色链霉菌actII-orf4、afsR和redD-orf1基因以及灰色链霉菌strS、糖多孢红霉菌eryC1和嗜热脂肪芽孢杆菌degT基因的产物之间的序列比较揭示了两个假定的调控基因家族。DegT、DnrJ、EryC1和StrS家族的成员表现出其他细菌双组分调控系统的蛋白激酶（传感器）成分的一些特征（尽管这四种蛋白质的序列均未显示与此类蛋白激酶有显著的整体或区域相似性），并且具有DNA结合蛋白典型的共有螺旋-转角-螺旋基序。另一个家族的两种蛋白质AfsR和RedD-Orf1中也存在螺旋-转角-螺旋基序。两组链霉菌蛋白可能都是参与调控次级代谢的反式作用因子。
