Institut für Angewandte Biowissenschaften, Angewandte Biologie, Karlsruher Institut für Technologie, Karlsruhe, Germany.
Appl Environ Microbiol. 2012 Feb;78(4):913-21. doi: 10.1128/AEM.06803-11. Epub 2011 Dec 16.
An extension of the respiratory chain to the cell surface is necessary to reduce extracellular electron acceptors like ferric iron or manganese oxides. In the past few years, more and more compounds were revealed to be reduced at the surface of the outer membrane of Gram-negative bacteria, and the list does not seem to have an end so far. Shewanella as well as Geobacter strains are model organisms to discover the biochemistry that enables the dissimilatory reduction of extracellular electron acceptors. In both cases, c-type cytochromes are essential electron-transferring proteins. They make the journey of respiratory electrons from the cytoplasmic membrane through periplasm and over the outer membrane possible. Outer membrane cytochromes have the ability to catalyze the last step of the respiratory chains. Still, recent discoveries provided evidence that they are accompanied by further factors that allow or at least facilitate extracellular reduction. This review gives a condensed overview of our current knowledge of extracellular respiration, highlights recent discoveries, and discusses critically the influence of different strategies for terminal electron transfer reactions.
细胞表面的呼吸链需要向外延伸，以还原细胞外电子受体，如三价铁或锰氧化物。在过去的几年中，越来越多的化合物被发现可以在外膜的表面被还原，而且到目前为止，这个清单似乎还没有尽头。希瓦氏菌和地杆菌菌株是发现能够异化还原细胞外电子受体的生物化学的模式生物。在这两种情况下，c 型细胞色素都是必不可少的电子转移蛋白。它们使呼吸电子从细胞质膜通过周质并穿过外膜成为可能。外膜细胞色素具有催化呼吸链最后一步的能力。然而，最近的发现提供了证据，证明它们还伴随着其他允许或至少促进细胞外还原的因素。这篇综述简要概述了我们目前对外呼吸的认识，强调了最近的发现，并批判性地讨论了不同的末端电子转移反应策略的影响。
