Lee B C
Department of Microbiology and Infectious Diseases, The University of Calgary, Alberta, Canada.
Mol Microbiol. 1995 Nov;18(3):383-90. doi: 10.1111/j.1365-2958.1995.mmi_18030383.x.
Haem is an important bacterial nutrient. As a prosthetic group of several proteins, haem functions as a cofactor mediating oxygen transport, energy generation, and mixed-function oxidation. In addition, the iron chelated in the porphyrin ring may serve as an iron substrate for growth. However, because of its propensity for oxidizing cellular constituents, haem is always associated with proteins. Therefore, the uptake and transit of haem across bacterial membranes requires the participation of protein escorts. Bacteria have evolved a diverse array of surface-exposed receptors dedicated to binding haem and haem-proteins. Following this selective recognition at the bacterial cell surface, haem is transported across the outer membrane via a TonB-dependent process. The control of receptor expression appears to be multifactorial, probably involving a number of global regulators. A model integrating this information is presented.
血红素是一种重要的细菌营养物质。作为几种蛋白质的辅基，血红素作为一种辅助因子发挥作用，介导氧气运输、能量产生和混合功能氧化。此外，螯合在卟啉环中的铁可作为生长的铁底物。然而，由于血红素易于氧化细胞成分，它总是与蛋白质结合。因此，血红素跨细菌膜的摄取和转运需要蛋白质护送者的参与。细菌已经进化出各种各样暴露于表面的受体，专门用于结合血红素和血红素蛋白。在细菌细胞表面进行这种选择性识别之后，血红素通过依赖TonB的过程跨外膜运输。受体表达的控制似乎是多因素的，可能涉及许多全局调节因子。本文提出了一个整合这些信息的模型。
