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首页> 外文期刊>Journal of bacteriology >Self-cloning in Streptomyces griseus of an str gene cluster for streptomycin biosynthesis and streptomycin resistance.
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Self-cloning in Streptomyces griseus of an str gene cluster for streptomycin biosynthesis and streptomycin resistance.

机译：用于链霉素生物合成和链霉素抗性的str基因簇的灰色链霉菌中的自我克隆。

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An str gene cluster containing at least four genes (strR, strA, strB, and strC) involved in streptomycin biosynthesis or streptomycin resistance or both was self-cloned in Streptomyces griseus by using plasmid pOA154. The strA gene was verified to encode streptomycin 6-phosphotransferase, a streptomycin resistance factor in S. griseus, by examining the gene product expressed in Escherichia coli. The other three genes were determined by complementation tests with streptomycin-nonproducing mutants whose biochemical lesions were clearly identified. strR complemented streptomycin-sensitive mutant SM196 which exhibited impaired activity of both streptomycin 6-phosphotransferase and amidinotransferase (one of the streptomycin biosynthetic enzymes) due to a regulatory mutation; strB complemented strain SD141, which was specifically deficient in amidinotransferase; and strC complemented strain SD245, which was deficient in linkage between streptidine 6-phosphate and dihydrostreptose. By deletion analysis of plasmids with appropriate restriction endonucleases, the order of the four genes was determined to be strR-strA-strB-strC. Transformation of S. griseus with plasmids carrying both strR and strB genes enhanced amidinotransferase activity in the transformed cells. Based on the gene dosage effect and the biological characteristics of the mutants complemented by strR and strB, it was concluded that strB encodes amidinotransferase and strR encodes a positive effector required for the full expression of strA and strB genes. Furthermore, it was found that amplification of a specific 0.7-kilobase region of the cloned DNA on a plasmid inhibited streptomycin biosynthesis of the transformants. This DNA region might contain a regulatory apparatus that participates in the control of streptomycin biosynthesis.
机译：通过使用质粒pOA154将含有至少四个参与链霉素生物合成或链霉素抗性或两者的基因（strR，strA，strB和strC）的str基因簇自克隆在灰链霉菌中。通过检查在大肠杆菌中表达的基因产物，证实strA基因编码链霉素6-磷酸转移酶，一种链霉菌中的链霉素抗性因子。其他三个基因是通过与不产生链霉素的突变体的互补试验确定的，这些突变体的生化病变已被明确鉴定。 strR补充了对链霉素敏感的突变体SM196，该突变体由于调节性突变而使链霉素6磷酸转移酶和a基转移酶（链霉素生物合成酶之一）的活性受损; strB补充了SD141，该菌株在氨基转移酶上特别缺乏;和strC互补的菌株SD245，其在6-磷酸链霉素与二氢链糖之间的连接不足。通过用适当的限制性核酸内切酶对质粒进行缺失分析，确定四个基因的顺序为strR-strA-strB-strC。用携带strR和strB基因的质粒转化灰链霉菌增强了转化细胞中酰胺转移酶的活性。根据基因剂量效应和由strR和strB互补的突变体的生物学特性，可以得出结论：strB编码酰胺基转移酶，而strR编码充分表达strA和strB基因所需的阳性效应子。此外，发现在质粒上克隆的DNA的特定0.7-碱基碱基区域的扩增抑制了转化体的链霉素生物合成。该DNA区域可能包含参与链霉素生物合成控制的调节装置。

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