部分革兰氏阴性菌TonB蛋白的结构特点及作用机制

Structural features and functional mechanism of TonB in some Gram-negative bacteria-A review

摘要:

摘要:在革兰氏阴性菌内，TonB系统对环境中的重要营养物质的摄取至关重要。TonB系统由锚定在内膜的ExbB-ExbD和周质蛋白TonB组成，它为TonB依赖性外膜受体(TBDTs)提供能量，使其转运营养物质。TonB系统普遍参与了铁、血红素、维生素B12、碳水化合物及多种过渡金属元素等多种重要物质的转运过程。TonB蛋白的功能与其特殊的结构密切相关，它的结构包括起固定作用的氨基端结构域、柔韧可变的脯氨酸富集的中间结构域和与TonB依赖性受体相互作用的羧基端结构域。虽然TonB蛋白结构特点较为清晰，但 其精确作用机制尚未被完全揭示。本文综述了革兰氏阴性菌TonB依赖性的营养物质摄取、TonB蛋白的结构特点、作用机制模型及表达调控，以期为进一步研究TonB蛋白功能提供理论基础和参考。

Abstract:

Abstract: TonB systems of gram-negative bacteria play an important role in transportation of nutriment from outside environments．TonB systems consist of plasma membrane proteins ExbB-ExbD and periplasmic protein TonB，which provide the energy to TonB-dependent receptors to transport substrates．These substrates include iron，hemin，vitamin B12，carbohydrate and some transition metal elements．The energy supporting function of TonB relies on its special structure which contains N-terminal domain for fixation，flexible periplasmic linker Pro-rich domain and C-terminal domain for contacting receptors．The precise mechanism of TonB system is not fully understood though its structural was studied a lot． To provide insights into direction for further research of TonB，we reviewed the TonB-dependent substrates uptake，structural features，functional mechanism and expression regulation of TonB.