Plater R, Robinson J A
Institute of Organic Chemistry, University of Zürich, Switzerland.
Gene. 1992 Mar 1;112(1):117-22. doi: 10.1016/0378-1119(92)90312-d.
A gene (nonR) conferring tetranactin resistance on the macrotetrolide-sensitive strain, Streptomyces lividans TK64, was isolated during a shotgun cloning experiment, in which chromosomal fragments from Streptomyces griseus were ligated into the vector pIJ699 and then introduced by transformation into S. lividans TK64. The sequence (3326 bp) of the cloned DNA revealed three complete open reading frames (ORFs) and one incomplete ORF encoded on one strand of the DNA. The nonR gene (designated here ORFA) encodes a polypeptide of 279 amino acids (Mr 30610) and contains a putative active site motif, GXSXG, characteristic of serine proteases and esterases. A functional role for the nonR gene product may involve the inactivation of the antibiotic through hydrolysis of one or more ester linkages in the macrotetrolide ring. The deduced product of the incomplete ORFX lying adjacent to ORFA showed 27.9% sequence identity with the C-terminal region of rat mitochondrial enoyl-CoA hydratase, and is possibly a macrotetrolide biosynthetic enzyme.
在一次鸟枪法克隆实验中，从对大元四内酯敏感的菌株天蓝色链霉菌TK64中分离出了一个赋予杀念菌素抗性的基因（nonR）。在该实验中，将灰色链霉菌的染色体片段连接到载体pIJ699中，然后通过转化导入天蓝色链霉菌TK64。克隆DNA的序列（3326 bp）显示在DNA的一条链上编码有三个完整的开放阅读框（ORF）和一个不完整的ORF。nonR基因（此处命名为ORFA）编码一个由279个氨基酸组成的多肽（Mr 30610），并含有一个假定的活性位点基序GXSXG，这是丝氨酸蛋白酶和酯酶的特征。nonR基因产物的功能作用可能涉及通过水解大元四内酯环中的一个或多个酯键来使抗生素失活。与ORFA相邻的不完整ORFX的推导产物与大鼠线粒体烯酰辅酶A水合酶的C末端区域显示出27.9%的序列同一性，可能是一种大元四内酯生物合成酶。
