Structure of bakterial ABC-transporters for maltose/maltodextrines

ABC转运系统家族包括多种转运蛋白，其将ATP水解的能量与溶质跨生物膜的易位偶联。该家族的成员已在属于三个主要王国的生物体中鉴定，其中一些具有医学意义（抗生素和多药耐药性，囊性纤维化）。这些蛋白质发挥其功能的分子机制仍然知之甚少，主要是由于缺乏三级结构信息。通过使用已被充分研究的ABC转运系统麦芽糖（Ma 1 FGK 2）的鼠伤寒沙门氏菌作为一个模式，我们将有助于该领域的调查。首先，我们将通过可用晶体的X射线衍射分析来解决ATP结合亚基Ma 1 K的结构。作为这些研究的补充，我们将通过NMR确定C-末端Ma 1 K片段的溶液结构。在第二组实验中，我们将尝试获得纯化的Ma 1FGK 2复合物的2D和3D晶体。通过电子显微镜和2D晶体的生产来分析制备将提供额外的结构信息。最后，同源运输系统的嗜热嗜酸细菌Alicyclobacillus acidocaldarius将作为一种替代方案进行研究，从而利用其增加的蛋白质稳定性在结晶实验。

The family of ABC transport systems comprises a diverse class of transport proteins that couple the energy of ATP hydrolysis to the translocation of solutes across biological membranes. Members of the family have been identified in organisms belonging to each of the three major kingdoms, some of them with medical relevance (antibiotic and multidrug resistance, cystic fibrosis). The molecular mechanism by which these proteins exert their functions is still poorly understood, mainly due to the lack of tertiary structural informations. By using the well-studied ABC transport system for maltose (Ma1FGK2) of salmonella typhimurium as a mode, we will contribute to the investigations of the field. First, we will solve the structure of the ATP-binding subunit Ma1K by X-ray diffraction analysis of available crystals. Complementary to these studies we will determine the solution structure of a C-terminal Ma1K fragment by NMR. In a second set of experiments we will attempt to obtain 2D- and 3D-crystals of the purified Ma1FGK2 complex. Analysis of the preparation by electron microscopy and the production of 2D crystals will provide additional structural informations. Finally, a homologous transport system from the thermoacidophilic bacterium Alicyclobacillus acidocaldarius will be studied as an alternative, thereby taking advantage from its increased protein stability in crystallization experiments.