Inorganic Chemistry Laboratory, University of Oxford, OX1 3QR, UK.
J Mol Biol. 2011 Jan 14;405(2):427-35. doi: 10.1016/j.jmb.2010.10.053. Epub 2010 Nov 12.
Shigella flexneri Spa15 is a chaperone of the type 3 secretion system, which binds a number of effectors to ensure their stabilization prior to secretion. One of these effectors is IpgB1, a mimic of the human Ras-like Rho guanosine triphosphatase RhoG. In this study, Spa15 alone and in complex with IpgB1 has been studied by double electron electron resonance, an experiment that gives distance information showing the spacial separation of attached spin labels. This distance is explained by determining the crystal structure of the spin-labeled Spa15 where labels are seen to be buried in hydrophobic pockets. The double electron electron resonance experiment on the Spa15 complex with IpgB1 shows that IpgB1 does not bind Spa15 in the same way as is seen in the homologous Salmonella sp. chaperone:effector complex InvB:SipA.
福氏志贺氏菌 Spa15 是 III 型分泌系统的伴侣蛋白，可结合多种效应蛋白，以确保在分泌前稳定这些效应蛋白。其中一种效应蛋白是 IpgB1，它模拟人类 Ras 样 Rho 鸟苷三磷酸酶 RhoG。在这项研究中，我们通过双电子电子共振实验单独研究了 Spa15 及其与 IpgB1 的复合物，该实验提供了距离信息，显示了附着的自旋标记物之间的空间分离。通过确定自旋标记 Spa15 的晶体结构来解释这种距离，在该结构中，可以看到标记物埋藏在疏水性口袋中。对 Spa15 与 IpgB1 复合物的双电子电子共振实验表明，IpgB1 与 Spa15 的结合方式与在同源性沙门氏菌属 chaperone:effector 复合物 InvB:SipA 中观察到的方式不同。
