Karlsson M, Hannavy K, Higgins C F
Imperial Cancer Research Fund Laboratories, University of Oxford, John Radcliffe Hospital, UK.
Mol Microbiol. 1993 Apr;8(2):389-96. doi: 10.1111/j.1365-2958.1993.tb01582.x.
The TonB protein is required to transduce energy from the cytoplasmic membrane to outer membrane transport proteins of Gram-negative bacteria. Two accessory proteins, ExbB and ExbD, are required for TonB function and it has been suggested that TonB and ExbBD form a complex in the membrane. In this paper we demonstrate that there are two spatially distinct, functional interactions between ExbBD and TonB. First, there is an interaction between ExbBD and the N-terminal signal-like peptide of TonB, probably the formation of a stable complex in the membrane. Second, ExbB interacts with TonB in the cytoplasm. This interaction involves the domain of TonB that is normally periplasmic. Thus, this is a transient interaction which occurs during the synthesis and/or localization of TonB, implying a chaperone-like role for ExbB. The transmembrane topology of ExbB was shown to be consistent with this role.
托蛋白（TonB蛋白）是将能量从细胞质膜传递到革兰氏阴性菌外膜转运蛋白所必需的。托蛋白发挥功能需要两种辅助蛋白，即ExbB和ExbD，并且有人提出托蛋白与ExbBD在膜中形成复合物。在本文中，我们证明ExbBD与托蛋白之间存在两种空间上不同的功能性相互作用。首先，ExbBD与托蛋白的N端信号样肽之间存在相互作用，这可能是在膜中形成稳定复合物。其次，ExbB在细胞质中与托蛋白相互作用。这种相互作用涉及托蛋白通常位于周质的结构域。因此，这是一种在托蛋白合成和/或定位过程中发生的瞬时相互作用，这意味着ExbB具有类似分子伴侣的作用。已证明ExbB的跨膜拓扑结构与此作用一致。
