Structural and functional characterization of sugar transporters in health and disease

 描述（由申请人提供）：葡萄糖是几乎所有生物体中普遍存在的细胞燃料来源。除了其在人体中的能量作用外，葡萄糖还充当关键的代谢中间体，其中活化的葡萄糖分子被转运到ER和高尔基体，并用于糖基化蛋白质、脂质和多糖，作为生物合成-分泌途径的一部分。葡萄糖和其他膳食单糖进入体内的途径很常见，它们被小肠的肠上皮细胞吸收，并在血流中分布在全身。血糖浓度通过激素控制和肾脏保守的重吸收机制严格维持。次级主动转运蛋白促进这些吸收/重吸收过程以及将活化的葡萄糖分子专门递送到ER和高尔基体。其固有功能的改变导致许多人类疾病和病症，如II型糖尿病;因此，对其结构和动力学的复杂理解是生物医学研究的关键目标。 在最初的赠款周期中，我们解决了钠葡萄糖转运蛋白家族成员的第一个晶体结构，副溶血性弧菌钠/半乳糖同向转运蛋白（vSGLT）。在随后的更新中，我们解决了vSGLT的向内开放构象的其他结构，结合生物化学和分子动力学模拟，揭示了允许底物释放的机制。这两个不同的构象在此过程中获得的补助金从根本上推进了我们的理解膜运输到原子水平，是这种竞争性的更新的基础。此外，我们的目标是解决哺乳动物转运蛋白（特别是智人）的SGLT（SLC 5家族），以及一个独特的，但结构上尚未解决的一类核苷酸糖转运蛋白，SLC 35家族。此次更新的目标是：目标1使用双电子-电子共振和广角X射线散射捕获vSGLT的完整传输循环。目的2和3在结构上解析具有药物相关性的两类人转运蛋白，溶质钠同向转运蛋白家族（SLC 5）和核苷酸糖转运蛋白家族（SLC 35）。阐明这些转运家族的结构基础将增加我们对相关疾病的理解，并有助于药物开发。

 DESCRIPTION (provided by applicant): Glucose is a ubiquitous cellular fuel source in virtually all organisms. In addition to its energetic role in the human body, glucose also serves as a critical metabolic intermediate in which activated glucose molecules are transported to the ER and Golgi and used for glycosylating proteins, lipids and polysaccharides as part of the biosynthetic-secretory pathway. The path of entry to the body is common for glucose and the other dietary monosaccharides, which are absorbed by enterocytes of the small intestine and distributed throughout the body in the bloodstream. The plasma glucose concentration is tightly maintained by hormonal control and conserved reabsorption mechanisms in the kidneys. Secondary active transporters facilitate these absorption/reabsorption processes as well as the exclusive delivery of activated glucose molecules to the ER and Golgi. Alterations in their inherent functions result in numerous human diseases and disorders, such as type II diabetes; thus, an intricate understanding of their structure and dynamics is a critical objective for biomedical research. During the original grant cycle, we solved the first crystal structure for an member of the sodium glucose transporter family, the Vibrio parahaemolyticus sodium/galactose symporter (vSGLT). On the subsequent renewal, we solved additional structures of the inward-open conformation of vSGLT, which in conjunction with biochemical and molecular dynamics simulations reveals the mechanism allowing substrate release. These two distinct conformations obtained during the course of this grant have fundamentally advanced our understanding of membrane transport to an atomic level and are the foundation for this competitive renewal. In addition, we aim to resolve mammalian transporters (in particular Homo sapiens) of SGLT (SLC5 family) as well as a distinct, and as of yet structurally unresolved class of nucleotide sugar transporters, the SLC35 family. The aims of this renewal are: Aim 1 captures a complete transport cycle for vSGLT using double electron-electron resonance and wide-angle x-ray scattering. Aims 2 and 3 structurally resolve two classes of human transporters with pharmaceutical relevance, the Solute Sodium Symporter family (SLC5) and the Nucleotide Sugar Transporters family (SLC35). Elucidating the structural basis for these transport families will increase our understanding of the related diseases and aid in drug development.