Genetic control of denitrification in Pseudomonas aeruginosa

描述（由申请方提供）：铜绿假单胞菌感染是囊性纤维化发病率和死亡率的主要原因。这种生物体在气道中的存在很大程度上是通过其在氧气有限的条件下产生能量的能力，这种条件定义了患病肺部中的脱水粘液。这个小额赠款项目将推进控制能量代谢的转录调节机制的知识。Anr和Dnr蛋白是Crp-Fnr超家族转录激活因子的成员，被认为差异调节微需氧或无氧呼吸所需产物的基因表达。这种差异调节的机制尚不清楚。一种假设是，不同的特异性决定因素的Anr和Dnr的结合服务，以指导每个监管机构适当的操纵子。另一种假设是，Anr和Dnr具有相似的结合特异性决定簇，但这些调节因子在不同的生理条件下发挥作用。我建议通过比较两个代表性转录控制区的表达来区分这两种假设。在其他人先前的研究中，编码精氨酸发酵酶的arcD操纵子被认为仅受Anr调节，而编码一氧化二氮还原酶的nosR操纵子被认为仅受Dnr调节。实验将监测arcD和nosR定向转录在不同的生长条件下，在anr和dnr无效突变体，并在菌株中，其中anr和dnr的组成型表达。这些试验结果将为进一步分析Anr和Dnr控制微氧和无氧呼吸提供依据。如果第一个假设是正确的，差异结合特异性的决定因素将被确定。如果第二个假设是正确的，具体的作用Anr-和Dnr-调节基因表达将进一步检查，以文件的生理参数，如氧限制和一氧化氮的具体反应。公共卫生相关性：铜绿假单胞菌感染是囊性纤维化发病率和死亡率的主要原因。这种生物体在气道中的存在很大程度上是通过其在氧气有限的条件下产生能量的能力，这种条件定义了患病肺部中的脱水粘液。这个小额赠款项目将推进控制能量代谢的转录调节机制的知识。

DESCRIPTION (provided by applicant): Pseudomonas aeruginosa infection is the major cause of morbidity and mortality in cystic fibrosis. The organism persists in airways in large part through its ability to generate energy under the oxygen-limited conditions that define the dehydrated mucus in diseased lungs. This small-grant project will advance knowledge of transcription regulatory mechanisms that control energy metabolism. The Anr and Dnr proteins, members of the Crp-Fnr superfamily of transcription activators, are thought to differentially regulate expression of genes whose products are required for microaerobic or anaerobic respiration. The mechanism for this differential regulation is unclear. One hypothesis is that distinct specificity determinants for Anr and Dnr binding serve to direct each regulator to the appropriate operons. An alternative hypothesis is that Anr and Dnr have similar binding specificity determinants, but that these regulators function under different physiological conditions. I propose to distinguish between these two hypotheses by comparing expression from two representative transcription control regions. In previous studies by others, the arcD operon encoding arginine fermentation enzymes has been suggested to be regulated exclusively by Anr, whereas the nosR operon encoding nitrous oxide reductase has been suggested to be regulated exclusively by Dnr. Experiments will monitor arcD- and nosR-directed transcription under different growth conditions, in anr and dnr null mutants, and in strains in which anr and dnr are expressed constitutively. Results from these tests will provide the basis for further analysis of Anr and Dnr control of microaerobic and anaerobic respiration. If the first hypothesis is correct, the determinants for differential binding specificity will be identified. If the second hypothesis is correct, specific roles for Anr- and Dnr- regulated gene expression will be examined further in order to document specific responses to physiological parameters such as oxygen limitation and nitric oxide. PUBLIC HEALTH RELEVANCE: Pseudomonas aeruginosa infection is the major cause of morbidity and mortality in cystic fibrosis. The organism persists in airways in large part through its ability to generate energy under the oxygen-limited conditions that define the dehydrated mucus in diseased lungs. This small-grant project will advance knowledge of transcription regulatory mechanisms that control energy metabolism.