Structure and Function of SWEET Sugar Transporters

SWEET糖转运蛋白的结构和功能

• 批准号: 9333389
• 负责人: Liang Feng
• 金额: $ 31.21万
• 依托单位: STANFORD UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-09-01 至 2020-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9333389
• 关键词: Active Biological Transport; Amino Acids; Architecture; Biological Assay; Biological Models; Blood Glucose; Carbon; Carrier Proteins; Complement; Crystallization; Cystinosis; Data; Diabetes Mellitus; Diffusion; Dimerization; Disaccharides; Drug Targeting; Electron Spin Resonance Spectroscopy; Energy-Generating Resources; Evolution; Future; Goals; Growth; Homeostasis; Homologous Gene; In Vitro; KDEL receptor; Knowledge; Learning; Light; Link; Lysosomal Storage Diseases; Lysosomes; Maintenance; Malignant Neoplasms; Mediating; Membrane; Membrane Proteins; Membrane Transport Proteins; Metabolism; Mitochondria; Modeling; Molecular; Molecular Conformation; Mono-S; Mutagenesis; Non-Insulin-Dependent Diabetes Mellitus; Organism; Physiological; Physiological Processes; Property; Protein Engineering; Protein Isoforms; Proteins; Research; Resolution; Sorting - Cell Movement; Spielmeyer-Vogt Disease; Structure; Substrate Specificity; Transmembrane Transport; Transport Process; Work; X-Ray Crystallography; Yeasts; biophysical techniques; cancer type; crosslink; dimer; driving force; drug development; improved; member; milk production; mutation screening; novel; novel therapeutics; prototype; public health relevance; pyruvate carrier; receptor; sugar; targeted treatment; therapeutic target; triple helix; uptake

 DESCRIPTION (provided by applicant): Sugar is a key source of energy for multicellular organisms, and its efflux across the membrane is critical to many physiological processes, including blood glucose maintenance and milk production. SWEET transporters (SWEETs) are novel membrane proteins that mediate sugar export. SWEETs are also prototypes of the large MtN3 membrane protein clan, which includes notable members such as mitochondrial pyruvate carrier, PQ-loop transporters and the KDEL receptor. Eukaryotic SWEETs, together with their "half transporter" bacterial homolog, SemiSWEET, are a unique model system to study the widely observed duplication-fusion in membrane protein evolution. Despite the importance of SWEETs in sugar utilization and MtN3 proteins in mitochondrial function, lysosomal amino acid homeostasis, and ER protein retention, we do not understand SWEET and MtN3 mechanisms at the molecular level. To overcome a major barrier to progress-the lack of a structural framework to guide our mechanistic understanding of transport-we have solved high-resolution structures of two SemiSWEET proteins, in two distinct conformational states: outward open and occluded. We will leverage this structural data to gain a detailed understanding of the structure and function of SWEETs and, more broadly, of MtN3s. Specific Aim 1: Elucidate the structural basis of sugar transport by SemiSWEET using X-ray crystallography and biophysical methods. These studies will help us understand the physical basis of sugar transport by SemiSWEETs. Specific Aim 2: Determine the first crystal structure of a eukaryotic SWEET. This structural information will provide a blueprint for the transport process and help elucidate the evolution of membrane transport proteins with internal symmetry. Specific Aim 3: Dissect the transport mechanism of SWEETs and MtN3s through functional studies. Fundamental aspects of SWEET-mediated transport will be elucidated and then extended to members of the MtN3 clan. OVERALL IMPACT: The proposed research will reveal the structural basis of sugar transport by SWEETs, elucidate their transport mechanism, and accelerate exploration of MtN3s as therapeutic targets to treat diabetes, cancer and lysosomal storage diseases.

 描述(申请人提供)：糖是多细胞生物体的主要能量来源，其跨膜排出对许多生理过程至关重要，包括维持血糖和产奶。糖转运蛋白是一种新型的膜蛋白，可以调节糖的输出。甜食也是大的MtN3膜蛋白家族的原型，该家族包括线粒体丙酮酸载体、PQ环转运体和KDEL受体等著名成员。真核糖和它们的半转运体细菌同源物半甜是研究膜蛋白进化中广泛观察到的复制-融合的独特模型系统。尽管甜食在糖利用和MtN3蛋白在线粒体功能、溶酶体氨基酸动态平衡和ER蛋白保留方面具有重要作用，但我们在分子水平上还不了解甜食和MtN3的作用机制。为了克服进展的一个主要障碍--缺乏一个结构框架来指导我们对运输的机械理解--我们解决了两个半甜蛋白质的高分辨率结构，它们处于两种不同的构象状态：向外开放和封闭。我们将利用这些结构数据来详细了解甜食以及更广泛的MtN3的结构和功能。具体目标1：用X射线结晶学和生物物理方法阐明半甜糖转运的结构基础。这些研究将有助于我们理解糖在半壁江山上运输的物理基础。具体目标2：确定真核糖的第一个晶体结构。这些结构信息将为转运过程提供蓝图，并有助于阐明具有内部对称性的膜转运蛋白的进化。具体目标3：通过功能研究剖析甜食和MtN3s的转运机制。甜蜜介导的运输的基本方面将被阐明，然后扩展到MtN3家族的成员。总体影响：拟议的研究将揭示糖通过糖果运输的结构基础，阐明其运输机制，并加快探索MtN3作为治疗糖尿病、癌症和溶酶体储存疾病的治疗靶点。