SAX ANALYSIS OF CHANGE: LIGAND BINDING TO GLUCOSE/GALACTOSE BINDING PROTEIN

这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 D-葡萄糖/D-半乳糖结合蛋白(GGBP)在许多细菌中介导对葡萄糖和半乳糖的趋化和主动转运。和其他周质结合蛋白一样，GGBP可以以开放(无配体，无活性)和封闭(配体结合，信号传递)的状态存在。利用我们实验室最近解决的GGBP开放的、未结合的晶体结构，我们设计了一个小分子作为GGBP的拮抗剂，通过抑制葡萄糖的趋化作用并将蛋白质楔入开放的构象。据我们所知，这是第一个(据我们所知)为这个庞大而多样化的家庭描述的对手。我们打算通过小角X射线散射(SAXS)实验进一步表征GGBP的拮抗剂结合态。我们建议对未结合的GGBP、生产性结合的(葡萄糖/半乳糖结合的)GGBP和拮抗剂结合的GGBP进行SAXS实验，以表征结合时溶液中发生的构象变化。这些实验的结果将有助于我们了解这种拮抗剂是如何工作的，并确定这种基于结构的设计方法是否可以被证明是抑制这种一般结构的受体的一般方法。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. D-Glucose/D-Galactose-binding protein (GGBP) mediates chemotaxis toward and active transport of glucose and galactose in a number of bacterial species. GGBP, like other periplasmic binding proteins, can exist in open (ligand-free, inactive) and closed (ligand-bound, signaling) states. Using an open, unbound crystal structure of GGBP recently solved by our lab, we have designed a small molecule that acts as a GGBP antagonist by inhibiting glucose chemotaxis and wedging the protein into an open conformation. This is the first (to our knowledge) antagonist described for this large and diverse family. We intend to further characterize the antagonist-bound state of GGBP via small angle X-ray scattering (SAXS) experiments. We propose to carry out SAXS experiments on unbound GGBP, productively-bound (glucose/galactose-bound) GGBP and antagonist-bound GGBP to characterize conformational changes that occur in solution upon binding. The results of these experiments will help us understand how this antagonist works and determine whether this structure-based design method could prove to be a general way to inhibit receptors of this general architecture.