Olson E R, Dunyak D S, Jurss L M, Poorman R A
Molecular Biology Research, Upjohn Company, Kalamazoo, Michigan 49007.
J Bacteriol. 1991 Jan;173(1):234-44. doi: 10.1128/jb.173.1.234-244.1991.
We describe the isolation and analysis of an Escherichia coli gene, dppA, and its role in dipeptide transport. dppA maps near min 79 and encodes a protein (DppA) that has regions of amino acid similarity with a peptide-binding protein from Salmonella typhimurium (OppA). Like OppA, DppA is found in the periplasmic space and thus is most likely a dipeptide-binding protein. Insertional inactivation of dppA results in the inability of a proline auxotroph to utilize Pro-Gly as a proline source. dppA-dependent Pro-Gly utilization does not require any of the three major proline transport systems, demonstrating that DppA is not simply a dipeptidase. An in vivo competition assay was used to show that DppA is probably involved in the transport of dipeptides other than Pro-Gly. Transcription of dppA is repressed by the presence of casamino acids, suggesting that the cell alters its dipeptide transport capabilities in response to an environmental signal.
我们描述了大肠杆菌基因dppA的分离与分析，及其在二肽转运中的作用。dppA定位于约79分钟处，编码一种蛋白质（DppA），该蛋白质与鼠伤寒沙门氏菌的一种肽结合蛋白（OppA）具有氨基酸相似区域。与OppA一样，DppA存在于周质空间，因此很可能是一种二肽结合蛋白。dppA的插入失活导致脯氨酸营养缺陷型无法利用Pro-Gly作为脯氨酸来源。依赖dppA的Pro-Gly利用不需要三种主要脯氨酸转运系统中的任何一种，这表明DppA不仅仅是一种二肽酶。体内竞争试验表明，DppA可能参与了除Pro-Gly之外的其他二肽的转运。casamino acids的存在会抑制dppA的转录，这表明细胞会根据环境信号改变其二肽转运能力。
