Analyses of sodium bioenergetics in Vibrio cholerae

描述(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。在许多不同系统发育类群的微生物中都发现了初级Na+泵，Na+离子的跨膜循环可能在几种细菌的生理中起着重要作用。最近完成的许多细菌基因组序列揭示了在许多生物体中存在编码各种钠依赖系统的基因，包括一些不知道有初级钠能量循环的生物。这表明这些细菌可以利用Na+作为偶联离子，而不是H+循环，或者除了H+循环之外。虽然人们对霍乱弧菌的钠能量循环在生理中的作用知之甚少，但霍乱弧菌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。在目前的应用中，我们将构建和分析霍乱弧菌中Na+挤出酶的明确突变体作为模式生物，以进一步了解这一非常复杂和重要的细菌生理学部分。我们建议通过使用广泛的遗传操作和复杂的生物能量学测量相结合的方法，全面和系统地分析细菌钠生物能量学的成分。拟议的研究结果不仅将加强我们对细菌中一般生物能量途径的理解，而且将为我们和其他人未来研究维持微生物中离子动态平衡的分子装置奠定坚实的基础。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发挥作用。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，并将有助于理解与霍乱弧菌在环境和宿主管腔中的生态有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.