Glycosylation and calcium as a code for tandem EGF-like repeat structure and dynamics

蛋白质执行生命所必需的许多不同任务。 所执行的具体任务取决于蛋白质分子的三维结构。 在自然界中，蛋白质的结构可以通过与离子（如钙）的相互作用或通过化学修饰（如添加糖基）来故意改变。 尽管据预测，大多数蛋白质都有糖附着在上面，形成所谓的糖蛋白，但科学家研究的10万多种蛋白质结构中只有一小部分是糖蛋白。 为了了解连接糖如何改变钙结合蛋白的结构，必须系统地研究连接糖的影响。 了解糖、钙和蛋白质的协同效应将使研究人员能够研究这些独特蛋白质形状的功能，并预测类似糖蛋白的结构。 该项目将招募来自代表性不足群体的研究生和本科生。 他们将获得蛋白质化学、核磁共振光谱和质谱方面的专业培训。有了这个奖项，NSF-EPSCoR和化学部的生命过程化学项目将资助路易斯安那州立大学的Megan Macnaughtan博士，以确定钙结合和糖基化对小鼠Notch 1 Abruptex区域结构的协同作用。 表皮生长因子样（EGF）重复序列的结构和功能，如Notch 1 Abruptex区域中的那些，由高度保守的糖基化和钙结合位点调节。 高亲和力的钙结合位点对串联EGF重复序列结构的影响已经得到了很好的研究，但糖基化的协同作用和单一作用尚未得到系统的研究。 将使用荧光分光光度法和核磁共振（NMR）光谱法研究Notch 1 Abruptex区域的EGF重复序列26-28，以确定钙解离常数和连续糖基化后的结构变化。 将使用NMR确定钙结合的糖基化EGF 26 -28的高分辨率三维结构，以确定重要的相互作用。 通过定义钙、聚糖和蛋白质之间的相互作用，将揭示对其他糖基化EGF重复序列结构和EGF重复序列功能调节的新见解，影响结构生物学和细胞信号传导领域。

Proteins carry out many different tasks that are necessary for life. The specific task performed depends on the 3-dimensional structure of the protein molecule. In nature, a protein's structure can be purposely altered through interaction with ions, like calcium, or by chemical modifications, such as adding a sugar group. Even though it is predicted that most proteins have sugars attached to them, forming so-called glycoproteins, only a small proportion of the 100,000+ protein structures studied by scientists are glycoproteins. To understand how attached sugars alter the structure of a calcium-binding protein, the effects of the attached sugars must be systematically investigated. Understanding the synergistic effects of the sugar, calcium, and protein will allow investigators to study the function of these unique protein shapes and to predict the structure of similar glycoproteins. Graduate and undergraduate students from underrepresented groups will be recruited for this project. They will acquire specialized training in protein chemistry, nuclear magnetic resonance spectroscopy, and mass spectrometry.With this award, NSF-EPSCoR and the Chemistry of Life Processes Program in the Chemistry Division are funding Dr. Megan Macnaughtan from Louisiana State University to determine the synergistic effects of calcium binding and glycosylation on the structure of the mouse Notch1 Abruptex region. The structure and function of epidermal growth factor-like (EGF) repeats, like those in the Notch1 Abruptex region, are regulated by highly conserved glycosylation and calcium-binding sites. The effects of high-affinity calcium-binding sites on the structure of tandem EGF repeats has been well-studied, but the synergistic and singular effects of glycosylation have not been systematically investigated. EGF repeats 26-28 of the Notch1 Abruptex region will be studied to determine the calcium dissociation constants and the structural changes upon sequential glycosylation using fluorescence spectrophotometry and nuclear magnetic resonance (NMR) spectroscopy. The high-resolution 3-dimensional structure of calcium-bound, glycosylated EGF26-28 will be determined using NMR to identify important interactions. By defining the interactions between calcium, the glycans, and the protein, new insights into the structure of other glycosylated EGF repeats and the regulation of EGF repeat function will be revealed, impacting the fields of structural biology and cellular signaling.