Structural Studies of Sugar Transporters

膜的运输，例如葡萄糖的吸收，对细胞是必不可少的。这样的过程通常是通过中介 通过次级膜转运蛋白。最大的次级转运体家族是主要的促进者 超家族(MFS)，迄今已确定超过5,000个成员，包括来自 来自人类的肌肉(GLUT4)和葡萄糖-6-磷酸转运体(G6PT)都参与了 2型糖尿病的发病机制。我们建议研究细菌同系物的转运机制。 GLUT4和G6PT，来自大肠杆菌的甘油-3-磷酸转运蛋白(GIpT)，使用结构生物学， 生物化学和光谱方法。在之前的资金周期中，我们确定了晶体 在3.3A分辨率下无底物形式的GIpT的结构。这种结构使人联想到一个“摇杆开关”。 底物运输机制。在下一个资金周期中，为了更好地了解GIpT的基础 特异性和底物诱导的构象变化，我们计划确定 两种底物结合形式的转运蛋白。我们还将测试摇杆开关机构，并检查 关键氨基酸残基在诱变、转运分析和光谱技术中的作用。 从GIpT获得的结构和机械信息可以直接用于改进我们的 对GLUT4和G6PT的理解。

Membrane transport, for example glucose uptake, Is essential to the cell. Such processes are often mediated by secondary membrane transporters. The largest secondary transporter family is the major facilitator superfamily (MFS), with more than 5,000 members identified to date, including the glucose transporter from muscle (Glut4) and the glucose-6-phosphate transporter (G6PT), both from human and both are involved in the pathogenesis of type 2 diabetes. We propose to study the transport mechanisms of a bacterial homolog of Glut4 and G6PT, the glycerol-3-phosphate transporter (GIpT) from E. coli, using structural biology, biochemistry and spectroscopic approaches. In the previous funding cycle, we determined the crystal structure of GIpT in a substrate-free form at 3.3 A resolution. The structure suggests a "rocker-switch" mechanism for substrate transport. In the next funding cycle, to better understand GIpT's substrate specificity and substrate-induced conformational change, we plan to determine the crystal structures of the transporter in two substrate-bound forms. We will also test the rocker-switch mechanism and examine the role that key amino acid residues play using mutagenesis, transport assays and spectroscopic techniques. The structural and mechanistic information gained from GIpT can be used directly to improve our understanding of Glut4 and G6PT.