Department of Biology, University of York, Heslington, York YO10 5DD, UK.
Biochem Soc Trans. 2011 Dec;39(6):1895-9. doi: 10.1042/BST20110736.
Typically, the redox proteins of respiratory chains in Gram-negative bacteria are localized in the cytoplasmic membrane or in the periplasm. An alternative arrangement appears to be widespread within the betaproteobacterial genus Neisseria, wherein several redox proteins are covalently associated with the outer membrane. In the present paper, we discuss the structural properties of these outer membrane redox proteins and the functional consequences of this attachment. Several tethered outer membrane redox proteins of Neisseria contain a weakly conserved repeated structure between the covalent tether and the redox protein globular domain that should enable the redox cofactor-containing domain to extend from the outer membrane, across the periplasm and towards the inner membrane. It is argued that the constraints imposed on the movement and orientation of the globular domains by these tethers favours the formation of electron-transfer complexes for entropic reasons. The attachment to the outer membrane may also affect the exposure of the host to redox proteins with a moonlighting function in the host-microbe interaction, thus affecting the host response to Neisseria infection. We identify putative outer membrane redox proteins from a number of other bacterial genera outside Neisseria, and suggest that this organizational arrangement may be more common than previously recognized.
通常，革兰氏阴性菌呼吸链的氧化还原蛋白位于细胞质膜或周质中。在β变形菌属奈瑟氏菌中，似乎存在一种广泛的替代排列方式，其中几种氧化还原蛋白与外膜共价结合。在本文中，我们讨论了这些外膜氧化还原蛋白的结构特性以及这种附着的功能后果。奈瑟氏菌的几种固定在外膜上的氧化还原蛋白含有一个在共价连接和氧化还原蛋白球状结构域之间的弱保守重复结构，这应该使包含氧化还原辅因子的结构域能够从外膜延伸，穿过周质并朝向内膜。有人认为，这些连接对球状结构域的运动和取向施加的限制有利于形成电子转移复合物，这是出于熵的原因。这种与外膜的附着也可能影响宿主对具有在宿主-微生物相互作用中兼职功能的氧化还原蛋白的暴露，从而影响宿主对奈瑟氏菌感染的反应。我们从奈瑟氏菌以外的其他一些细菌属中鉴定出了一些潜在的外膜氧化还原蛋白，并提出这种组织排列方式可能比以前认识到的更为普遍。
