Thomas M S, Drabble W T
Mol Gen Genet. 1984;195(1-2):238-45. doi: 10.1007/BF00332753.
The regulatory region of the gua operon of Escherichia coli is contained within a 2.1 kb EcoR1 restriction fragment isolated from a lambda pgua transducing phage. This DNA fragment was inserted into pPV33-II, a promoter-cloning vector, where it activated the gene(s) for tetracycline resistance. The level of tetracycline resistance conferred by the hybrid plasmid was reduced by the addition of guanine and increased by adenine, indicating the presence of the gua promoter. The cloned fragment codes for a polypeptide that complements in vivo the defective enzymes present in certain guaB mutants. This polypeptide was characterised using minicells and immunoprecipitation, and is presumed to correspond to the N-terminal region of IMP dehydrogenase.
大肠杆菌gua操纵子的调控区域包含在一个2.1 kb的EcoR1限制性片段中，该片段是从λpgua转导噬菌体中分离出来的。这个DNA片段被插入到pPV33-II（一种启动子克隆载体）中，在那里它激活了四环素抗性基因。添加鸟嘌呤会降低杂交质粒赋予的四环素抗性水平，而添加腺嘌呤则会提高该水平，这表明存在gua启动子。克隆片段编码一种多肽，该多肽在体内可互补某些guaB突变体中存在的缺陷酶。使用微小细胞和免疫沉淀对该多肽进行了表征，推测它对应于IMP脱氢酶的N端区域。
