TonB-dependent transporters: regulation, structure, and function.
TonB-dependent transporters: regulation, structure, and function.
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TonB 依赖性转运蛋白：调节、结构和功能。
DOI：
10.1146/annurev.micro.112408.134247
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发表时间：
2010
影响因子：
10.5
通讯作者：
Buchanan SK
中科院分区：
文献类型：
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作者：
Noinaj N;Guillier M;Barnard TJ;Buchanan SK
TonB依赖性转运蛋白（TBDTs）是细菌外膜蛋白，结合并转运铁螯合物（称为铁载体）以及维生素B12、镍络合物和碳水化合物。转运过程需要质子动力形式的能量和三种内膜蛋白TonB-ExbB-ExbD的复合物，以将这种能量传递到外膜。铁载体底物的复杂性从简单的小分子如柠檬酸盐到大蛋白如血清转铁蛋白和血红蛋白不等。由于铁的摄取对几乎所有细菌都至关重要，因此TBDT的表达以多种方式进行调节，包括金属依赖性调节剂，σ/抗σ因子系统，小RNA，甚至核糖开关。近年来，许多新的TBDT结构已被解决在各种状态下，导致铁载体的选择性和结合，跨外膜的信号转导，以及与TonB-ExbB-ExbD的相互作用的更完整的图片。然而，运输机制仍不清楚。本文就TBDT的调控、结构和功能的研究进展以及有待解决的问题作一综述。
TonB-dependent transporters (TBDTs) are bacterial outer membrane proteins that bind and transport ferric chelates called siderophores, as well as vitamin B12, nickel complexes, and carbohydrates. The transport process requires energy in the form of protonmotive force and a complex of three inner membrane proteins, TonB-ExbB-ExbD, to transduce this energy to the outer membrane. The siderophore substrates range in complexity from simple small molecules such as citrate to large proteins like serum transferrin and haemoglobin. Because iron uptake is vital for almost all bacteria, expression of TBDTs is regulated in a number of ways that include metal-dependent regulators, σ/anti-σ factor systems, small RNAs, and even a riboswitch. In recent years many new structures of TBDTs have been solved in various states, resulting in a more complete picture of siderophore selectivity and binding, signal transduction across the outer membrane, and interaction with TonB-ExbB-ExbD. However, the transport mechanism is still unclear. In this review, we summarize recent progress in understanding regulation, structure and function in TBDTs and questions remaining to be answered.
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影响因子：
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