革兰氏阴性菌TonB-ExbB-ExbD复合物的功能、作用机制、分布及进化分析

革兰氏阴性菌在生长繁殖过程中需要从外界摄取营养物质。一些小分子营养物质可以自由地通过革兰氏阴性菌的细胞膜，而一些大分子营养物质的转运需要特异性的TonB复合物依赖性的外膜受体进行转运。TonB复合物由TonB、ExbB、ExbD构成，是革兰氏阴性菌对外界营养物质主动转运过程的能量提供单位，在革兰氏阴性菌分布广泛。近年来，对TonB-ExbB-ExbD复合物的功能、结构及作用机制取得了重大研究进展，然而此复合物在不同的细菌也存在功能及作用机制上的差异。基于此背景，本文综述了TonB复合物的功能和结构研究进展，并分析了TonB复合物在革兰氏阴性菌中的分布、进化，比较了不同革兰氏阴性菌此复合物的差异，有助于进一步发现和揭示TonB复合物的新功能。

Functions,Mechanisms, Distributions and Evolution of the#br# TonB-ExbB-ExbD Complex of Gram-negative Bacteria

Gram-negative bacteria need to take nutrients from outside during growth and proliferation. Some small molecule nutrients can pass freely through the cell membrane of Gram-negative bacteria, while the transport of some macromolecular nutrients require specific TonB complex-dependent outer membrane receptors. The TonB complex are widely distributed in Gram-negative bacteria, which are composed of TonB, ExbB, and ExbD and acts as the energy supplying unit for the active transport of external macromolecular nutrients. In recent years, significant advances have been made in the study of the functions, structures, and mechanisms of the TonB-ExbB-ExbD complex. However, there are some differences in the functions and mechanisms of the TonB-ExbB-ExbD complex in different bacteria. In this paper, we review the function and structure of the TonB complex, and analyze the distribution and evolution of the TonB complex in Gram-negative bacteria, and compare the differences among the complexes of different Gram-negative bacteria. It is helpful to further discover and reveal the new functions and mechanisms of the TonB complex.