Brahamsha B, Greenberg E P
J Bacteriol. 1987 Aug;169(8):3764-9. doi: 10.1128/jb.169.8.3764-3769.1987.
A 2.7-kilobase Sau3A fragment of Spirochaeta aurantia DNA cloned in pBR322 complemented a trpE deletion in Escherichia coli. Deletion analysis and Tn5 mutagenesis of the resulting plasmid pBG100 defined a 2-kilobase-pair region that was required for both the complementation and the synthesis of 59,000- and 47,000-molecular-weight polypeptides (59K and 47K polypeptides) in maxicells. Both the 59K and the 47K polypeptides appear to be encoded by a single gene. A maxicell analysis of pBG100::Tn5 mutants suggests that the 47K polypeptide is not sufficient for the trpE complementation. In vitro and in vivo anthranilate synthetase (AS) assays indicate that the complementing activity encoded by pBG100 was functionally analogous to the AS component I of E. coli in that it utilized NH3 but not glutamine as the amino donor. pBG100 did not encode a glutamine amidotransferase activity, although the AS component I it encoded was capable of interacting with E. coli AS component II to catalyze the glutamine-requiring reaction. Expression appeared to depend on a promoter in the cloned S. aurantia DNA.
克隆于pBR322的橙黄螺旋体（Spirochaeta aurantia）DNA的一个2.7千碱基的Sau3A片段可弥补大肠杆菌中的trpE缺失。对所得质粒pBG100进行缺失分析和Tn5诱变，确定了一个2千碱基对的区域，该区域对于在大细胞中进行互补以及合成59,000和47,000分子量的多肽（59K和47K多肽）都是必需的。59K和47K多肽似乎都由单个基因编码。对pBG100::Tn5突变体进行的大细胞分析表明，47K多肽不足以实现trpE互补。体外和体内邻氨基苯甲酸合成酶（AS）测定表明，pBG100编码的互补活性在功能上类似于大肠杆菌的AS组分I，因为它利用NH3而不是谷氨酰胺作为氨基供体。pBG100不编码谷氨酰胺酰胺转移酶活性，尽管它编码的AS组分I能够与大肠杆菌AS组分II相互作用以催化需要谷氨酰胺的反应。表达似乎依赖于克隆的橙黄螺旋体DNA中的一个启动子。
