Centre for Molecular and Structural Biochemistry, School of Biological Sciences and School of Chemistry, University of East Anglia, Norwich NR47TJ, UK.
Mol Microbiol. 2012 Jul;85(2):201-12. doi: 10.1111/j.1365-2958.2012.08088.x. Epub 2012 May 30.
Many species of bacteria can couple anaerobic growth to the respiratory reduction of insoluble minerals containing Fe(III) or Mn(III/IV). It has been suggested that in Shewanella species electrons cross the outer membrane to extracellular substrates via 'porin-cytochrome' electron transport modules. The molecular structure of an outer-membrane extracellular-facing deca-haem terminus for such a module has recently been resolved. It is debated how, once outside the cells, electrons are transferred from outer-membrane cytochromes to insoluble electron sinks. This may occur directly or by assemblies of cytochromes, perhaps functioning as 'nanowires', or via electron shuttles. Here we review recent work in this field and explore whether it allows for unification of the electron transport mechanisms supporting extracellular mineral respiration in Shewanella that may extend into other genera of Gram-negative bacteria.
许多种类的细菌可以将厌氧生长与呼吸还原不溶性含 Fe(III)或 Mn(III/IV)的矿物质结合起来。有人认为，在希瓦氏菌属中，电子通过“孔-细胞色素”电子传递模块穿过外膜到细胞外基质。最近已经解析了这样一个模块的外膜细胞外-facing deca-血红素末端的分子结构。一旦在细胞外，电子如何从外膜细胞色素转移到不溶性电子汇，这是有争议的。这可能直接发生，也可能通过细胞色素的组装发生，也许作为“纳米线”起作用，或者通过电子穿梭体发生。在这里，我们回顾了这一领域的最新工作，并探讨了它是否允许统一支持希瓦氏菌属细胞外矿物质呼吸的电子传递机制，这种机制可能扩展到革兰氏阴性菌的其他属。
