Rodríguez-García A, de la Fuente A, Pérez-Redondo R, Martín J F, Liras P
Area of Microbiology, Faculty of Biology, University of León, Spain.
J Mol Microbiol Biotechnol. 2000 Oct;2(4):543-50.
A cluster of genes argCJBDRGH containing most of the arginine biosynthesis genes has been found in Streptomyces clavuligerus after sequencing a 8.3 kb DNA region containing overlapping sequences of two DNA fragments known to contain arginine biosynthesis genes. Subcloning, complementation of E. coli arginine auxotrophic strains and enzymatic assays confirmed the identity of each gene. S1 nuclease mapping studies and Northern hybridization analysis revealed the formation of two large transcripts corresponding to argCJBDR and argGH. The amount of each of these mRNAs is 10 to 44 times higher in a S. clavuligerus argR-disrupted mutant than in the wild type confirming the existence of an ArgR-mediated control of arginine biosynthesis gene expression. A low level constitutive monocistronic transcript of argR was observed in S. clavuligerus cells. Most of the argGH transcript initiating at an adenine 29 nt upstream of the argG initiation codon appears to stop at a termination stem and loop structure present downstream of the argG gene.
在对链霉菌中一个8.3 kb的DNA区域进行测序后，发现了一组包含大多数精氨酸生物合成基因的基因簇argCJBDRGH，该区域包含两个已知含有精氨酸生物合成基因的DNA片段的重叠序列。亚克隆、对大肠杆菌精氨酸营养缺陷型菌株的互补作用以及酶活性测定证实了每个基因的身份。S1核酸酶图谱研究和Northern杂交分析揭示了对应于argCJBDR和argGH的两个大转录本的形成。在链霉菌argR缺失突变体中，这些mRNA中的每一种的量比野生型高10至44倍，这证实了存在由ArgR介导的对精氨酸生物合成基因表达的控制。在链霉菌细胞中观察到了argR的低水平组成型单顺反子转录本。大多数从argG起始密码子上游29个核苷酸处的腺嘌呤开始的argGH转录本似乎在argG基因下游存在的终止茎环结构处终止。
