Analyses of sodium bioenergetics in Vibrio cholerae

描述（由申请人提供）：所有活细胞在初级离子泵的帮助下建立跨膜电化学梯度。初级Na+泵已被发现在许多微生物的相当不同的产碱组和跨膜循环的Na+离子可能在一些细菌的生理起着重要的作用。最近完成的许多细菌基因组序列揭示了许多生物体中存在编码各种钠依赖系统的基因，包括一些未知的主要钠能量循环。这表明这些细菌可以利用Na+作为偶联离子，而不是H+循环，或除了H+循环之外。虽然对钠能量循环在霍乱弧菌生理学中的作用知之甚少，但这种生物体基因组中编码的大量钠依赖系统的存在值得对其各种Na+泵进行研究。在本申请中，我们将构建和分析作为模式生物的霍乱弧菌中的Na+-挤出酶中的限定突变体，以进一步了解细菌生理学的这一非常复杂和重要的部分。我们提出了一个全面和系统的分析，有助于细菌钠生物能量学的组成部分，通过使用广泛的遗传操作结合先进的生物能量测量。拟议的研究结果不仅将提高我们的理解一般的生物能途径在细菌中，但将形成一个坚实的基础，为未来的调查，由我们自己和他人，分子装置维持离子稳态微生物。钠生物能量学可能在霍乱弧菌生命周期的环境和致病阶段都起作用。因此，我们的研究有可能产生与细菌生理学相关的基本观点，并将有助于理解与环境中和宿主内腔中的霍乱弧菌生态学相关的基本生物学概念，这些概念将适用于各种细菌物种。

DESCRIPTION (provided by applicant): All living cells establish transmembrane electrochemical gradients with the help of primary ion pumps. Primary Na+ pumps have been discovered in many microorganisms of quite diverse phylogenic groups and a transmembrane circulation of Na+ ions may play a significant role in the physiology of several bacteria. The recent completion of many bacterial genome sequences revealed the presence of genes encoding a variety of sodium-dependent systems in many organisms, including some that were not known to have a primary sodium cycle of energy. This indicates that these bacteria can utilize Na+ as a coupling ion instead of, or in addition to, the H+ cycle. Although little is known about the role of the sodium cycle of energy in the physiology of Vibrio cholerae, the presence of a multitude of sodium-dependent systems encoded in the genome of this organism merits the investigation of its various Na+ pumps. In the present application we will construct and analyze defined mutants in Na+-extruding enzymes in V. cholerae as a model organism to gain further insights into this very complex and important part of bacterial physiology. We propose a comprehensive and systematic analysis of the components that contribute to bacterial sodium bioenergetics by using extensive genetic manipulations in combination with sophisticated bioenergetic measurements. Results of the proposed study will not only enhance our understanding of the general bioenergetic pathways in bacteria, but will form a solid basis for future investigations, by ourselves and others, of the molecular devices maintaining ion homeostasis in microorganisms. Sodium bioenergetics probably plays a role in both the environmental and pathogenic phases of the V. cholerae life cycle. Thus, our research has the potential for generating fundamental perspectives related to bacterial physiology and will be of value to understanding basic biological concepts related to V. cholerae ecology in the environment and in the lumen of hosts that will be applicable to a variety of bacterial species.