Structure and function of complex of substrate-binding protein and macromolecule-specific ABC transpoter

分析了鞘氨醇单胞菌（Sphingomonassp，A1）大分子（藻酸盐）特异性ABC转运蛋白（导入蛋白：AlgM 1-AlgM 2/AlgS-AlgS）的结构与功能关系。AlgQ中的亚位点1特异性结合甘露糖醛酸。通过与藻酸盐结合的AlgQ接触，构成导入器的渗透酶（AlgM 1和AlgM 2）打开，从AlgQ接收藻酸盐，然后利用由AlgS（ATP酶）作用产生的ATP水解能量将藻酸盐导入胞质溶胶。这种ATP转运蛋白与负责低分子量底物转运的ABC转运蛋白不同，因为底物结合蛋白（AlgQ）形成允许藻酸盐（一种长链酸性多糖）通过的隧道。

The structure and function relationship of macromolecule(alginate)-specific ABC transporter (importer:AlgM1-AlgM2/AlgS-AlgS) of Sphingomonas sp, A1 was analyzed.The substrate-binding proteins (AlgQ) bind/reliese alginate by opening/closing the N-domein and C-domein. The subsite 1 in the AlgQ specifically binds mannuronate. Through the contact with alginate-bound AlgQ, the permeases (AlgM1 and AlgM2) constituting importer open, receive alginate from AlgQ, and then alginate is introduced into cytosol by using ATP-hydrolyzing energy, which is generated by the action of AlgS (ATPase). This ATP transporter was different from the ABC transporters responsible for the transport of low-molecular weight substrates in that the substrate-binding protein (AlgQ) forms the tunnel that allows the passage of alginate, a long chain acid polysaccharide.