Lee Donghan, Walsh Joseph D, Migliorini Molly, Yu Ping, Cai Tao, Schwieters Charles D, Krueger Susan, Strickland Dudley K, Wang Yun-Xing
Protein-Nucleic Acid Interaction Section, Structural Biophysics Laboratory, National Cancer Institute at Frederick, National Institutes of Health, Frederick, Maryland 21702, USA.
Protein Sci. 2007 Aug;16(8):1628-40. doi: 10.1110/ps.072865407.
The receptor-associated protein (RAP) is a molecular chaperone that binds tightly to certain newly synthesized LDL receptor family members in the endoplasmic reticulum (ER) and facilitates their delivery to the Golgi. We have adopted a divide-and-conquer strategy to solve the structures of the individual domains of RAP using NMR spectroscopy. We present here the newly determined structure of domain 2. Based on this structure and the structures of domains 1 and 3, which were solved previously, we utilized experimental small-angle neutron scattering (SANS) data and a novel simulated annealing protocol to characterize the overall structure of RAP. The results reveal that RAP adopts a unique structural architecture consisting of three independent three-helix bundles that are connected by long and flexible linkers. The flexible linkers and the quasi-repetitive structural architecture may allow RAP to adopt various possible conformations when interacting with the LDL receptors, which are also made of repetitive substructure units.
受体相关蛋白(RAP)是一种分子伴侣,它在内质网(ER)中与某些新合成的低密度脂蛋白受体家族成员紧密结合,并促进它们向高尔基体的转运。我们采用了分而治之的策略,利用核磁共振光谱法解析了RAP各个结构域的结构。在此,我们展示了新确定的结构域2的结构。基于该结构以及先前解析的结构域1和结构域3的结构,我们利用实验性小角中子散射(SANS)数据和一种新颖的模拟退火协议来表征RAP的整体结构。结果表明,RAP采用了一种独特的结构架构,由三个独立的三螺旋束组成,这些三螺旋束通过长而灵活的连接子相连。灵活的连接子和准重复的结构架构可能使RAP在与同样由重复亚结构单元组成的低密度脂蛋白受体相互作用时能够采取各种可能的构象。