Bioenergetics of the predatory lifestyle of Bdellovibrio bacteriovorus

革兰氏阴性细菌噬菌蛭弧菌具有掠夺性的生活方式：它附着并进入其他革兰氏阴性细菌的周质，导致所谓蛭弧菌的形成。它在宿主体内复制，最终导致猎物溶解并释放出一小部分蛭弧菌。使这种生活方式成为可能的分子途径非常复杂，对介导捕食过程的理解仍处于起步阶段。然而，细菌的捕食不仅在科学方面（仅意味着对途径的理解）令人感兴趣，而且可能被证明是替代抗生素的医学治疗的一个有希望的机会。关于医疗应用的第一项研究已经进行，但在B之前。由于噬菌菌体可以在商业上使用，因此更好地理解导致宿主裂解的过程是不可避免的。许多有趣的和迄今尚未探索的捕食问题之一是生物能量方面。因此，阐明发生在捕食者细胞质膜的分子（运输）过程应是拟议项目的主要目标。对B的初步筛选。噬菌菌体基因组序列的鉴定导致了几种膜整合复合物的鉴定，这些复合物可能介导电子转移和伴随的离子转运、pH稳态、渗透适应以及化学渗透ATP合成。令人惊讶的是，生物信息学分析显示，在ATP合酶的c亚基中存在Na+结合基序，这表明Na+是该细菌中ADP磷酸化的偶联离子。如果实验分析将证实这一发现，B。bacteriovorus可能是第一个已知的好氧原核生物与Na+为基础的生物能量学。因此，几个选定的膜复合物（包括ATP合酶及其耦合离子）的功能和它们在捕食中的作用，应阐明使用生物化学，遗传学和细胞生物学的方法。

The Gram-negative bacterium Bdellovibrio bacteriovorus has a predatory lifestyle: it attaches to and enters the periplasm of other Gram-negative bacteria, leading to the formation of a so-called bdelloplast. It replicates within the host, finally leading to lysis of the prey and the release of a small Bdellovibrio population. The molecular pathways that enable this lifestyle are very complex and the understanding of the processes mediating predation is still in its beginnings. However, predation of bacteria is not only intriguing in terms of scientific aspects (meaning the understanding of the pathways only), but might also prove to be a promising opportunity for medical treatments as an alternative to antibiotics. First studies concerning a medical application have already been performed, but before B. bacteriovorus can be used commercially, a better understanding of the processes leading to the lysis of the host is inevitable.One of many interesting and so far unexplored issues of predation is the bioenergetic aspect. Therefore, an elucidation of the molecular (transport) processes occurring at the cytoplasmic membrane of the predator shall be the main objective of the proposed project. A preliminary screen of the B. bacteriovorus genome sequence resulted in the identification of several membrane-integral complexes that might mediate electron transfer and concomitant ion transport, pH homeostasis, osmotic adaptation, as well as chemiosmotic ATP synthesis. Astonishingly, bioinformatic analysis revealed the presence of a Na+ binding motif in the c subunit of the ATP synthase, suggesting that Na+ is the coupling ion for ADP phosphorylation in this bacterium. If experimental analysis will confirm this finding, B. bacteriovorus might be the first known aerobic prokaryote with Na+-based bioenergetics. Therefore, the function of several selected membrane complexes (including the ATP synthase and its coupling ion) and their role in predation shall be elucidated using biochemical, genetic, and cell biological approaches.