Nohno T, Saito T, Hong J S
Mol Gen Genet. 1986 Nov;205(2):260-9. doi: 10.1007/BF00430437.
The glutamine permease operon encoding the high-affinity transport system of glutamine in Escherichia coli could be cloned in one of the mini F plasmids, but not in pBR322 or pACYC184, by selection for restoration of the Gln+ phenotype, the ability to utilize glutamine as a sole carbon source. We determined the nucleotide sequence of the glutamine permease operon, which contains the structural gene of the periplasmic glutamine-binding protein (glnH), and indispensable component of the permease activity. The N-terminal amino acid sequence and the overall amino acid composition of the purified glutamine-binding protein were in good agreement with those predicted from the nucleotide sequence, if the N-terminal 22 amino acid residues were discounted. The latter comprised two Lys residues (nos. 2 and 6) followed by 16 hydrophobic amino acid residues and was assumed to be a signal peptide for transport into the periplasmic space. There were two additional reading frames (glnP and glnQ) downstream of glnH sharing a common promoter. It was concluded that the glnP and glnQ proteins as well as the glnH protein are essential for glutamine permease activity.
通过选择恢复Gln⁺表型（即利用谷氨酰胺作为唯一碳源的能力），编码大肠杆菌中谷氨酰胺高亲和力转运系统的谷氨酰胺通透酶操纵子可以克隆到一种微型F质粒中，但不能克隆到pBR322或pACYC184中。我们测定了谷氨酰胺通透酶操纵子的核苷酸序列，该操纵子包含周质谷氨酰胺结合蛋白（glnH）的结构基因，它是通透酶活性不可或缺的组成部分。如果不考虑N端的22个氨基酸残基，纯化的谷氨酰胺结合蛋白的N端氨基酸序列和整体氨基酸组成与从核苷酸序列预测的结果高度一致。后者包含两个赖氨酸残基（第2和6位），随后是16个疏水氨基酸残基，被认为是转运到周质空间的信号肽。在glnH下游还有另外两个阅读框（glnP和glnQ），它们共享一个共同的启动子。得出的结论是，glnP和glnQ蛋白以及glnH蛋白对于谷氨酰胺通透酶活性至关重要。
