Sondej M, Sun J, Seok Y J, Kaback H R, Peterkofsky A
Laboratory of Biochemical Genetics, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA.
Proc Natl Acad Sci U S A. 1999 Mar 30;96(7):3525-30. doi: 10.1073/pnas.96.7.3525.
Mediated by the protein IIAGlc, the phosphoenolpyruvate:sugar phosphotransferase system plays a role in the regulation of activity of other sugar transport systems in Escherichia coli. By using a direct binding assay, a collection of single-Cys replacement mutants in cytoplasmic loops of lactose permease were evaluated for their capacity to bind IIAGlc. Selected Cys replacements in loops IV/V or VI/VII result in loss of binding activity. Analysis of the mutagenesis results together with multiple sequence alignments of a family of proteins that interacts with IIAGlc provides the basis for developing two regions of consensus sequence in those partner proteins necessary for binding to IIAGlc. The requirement for two interaction regions is interpreted in the regulatory framework of a substrate-dependent conformational change that brings those two regions into an orientation optimal for binding IIAGlc.
糖磷酸转移酶系统由蛋白IIAGlc介导,在大肠杆菌中其他糖转运系统活性的调节中发挥作用。通过直接结合试验,对乳糖通透酶细胞质环中一系列单半胱氨酸替代突变体结合IIAGlc的能力进行了评估。在环IV/V或VI/VII中选择的半胱氨酸替代导致结合活性丧失。对诱变结果的分析以及与IIAGlc相互作用的一类蛋白质的多序列比对,为在那些与IIAGlc结合所必需的伴侣蛋白中开发两个共有序列区域提供了基础。对两个相互作用区域的需求在底物依赖性构象变化的调节框架中得到解释,这种变化使这两个区域处于最适合结合IIAGlc的方向。