ToxR/S and Unsaturated Fatty Acid Regulation in Photobacterium profundum Strain SS9

深光杆菌菌株 SS9 中的 ToxR/S 和不饱和脂肪酸调节

• 批准号: 9974528
• 负责人: Douglas Bartlett
• 金额: $ 30.5万
• 依托单位: University of California-San Diego Scripps Inst of Oceanography
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-09-01 至 2003-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9974528&HistoricalAwards=false
• 关键词: ToxR; Unsaturated; Fatty; Acid; Regulation

BartlettThe ToxR/S regulon is widely distributed among bacteria of the family Vibrionaceae. However, little is known about the nature or even the number of genes regulated by these proteins, except for some genes involved in human colonization and pathogenesis which have been acquired by horizontal gene transfer in Vibrio cholerae. Recent experiments in the investigator's lab indicate that ToxR and ToxS influence the ability of the deep-sea bacterium Photobacterium profundum strain SS9 to respond to changes in pressure and to grow at elevated pressure. Furthermore, in this organism, ToxR/S, together with the cyclic AMP receptor protein (CRP), appears to modulate the levels of unsaturated fatty acids (UFA's). It has previously been suggested that UFA's may be important factors in the adaptation of the membrane to elevated pressure and to decreased temperature. During this project the investigator will characterize the ToxR/S regulon in general, and the pressure and temperature regulation of UFA's in particular, in SS9. The connection between toxRS gene expression and growth inhibition at elevated pressure will be clarified. ToxR/S regulated genes will be identified using both genetic and molecular screening strategies. A subset of these genes will then be sequenced, their transcriptional regulation characterized, and their functions ascertained through mutant studies. Additional studies will specifically explore the possibility of transcriptional, translational, and posttranslational regulation of UFA's by pressure and temperature. Transcriptional regulation of genes whose products govern the levels of cis-vaccenic acid and eicosapentaenoic acid will be determined as a function of temperature and pressure in various regulatory protein mutant backgrounds. Finally, the regulation of the activity of 0-ketoacyl-ACP synthase II, which is required for high pressure and low temperature regulation of cis-vaccenic acid levels, will be examined through kinetic analyses.Despite the fact that the deep sea represents the largest part of our planet where life is found, little is known about the adaptations of organisms to this cold environment where the water pressure can exceed 15,000 pounds per square inch. In this project a bacterial species isolated from the bottom of the ocean will be used for genetic and physiological experiments to address the control of membrane components (unsaturated fatty acids) which are required for its growth and survival at low temperature and high pressure. The possibility that an enzyme responsible for making unsaturated fatty acids in this microorganism possesses unique characteristics suiting it to deep-sea conditions will be explored. The investigator will seek to identify additional cell functions which help the organism adjust to high pressure. The results will be of use in understanding the adaptation of life to extreme environments and will provide new information about how cells maintain proper membrane function.

ToxR/S调控子广泛分布于弧菌科细菌中。然而，除了在霍乱弧菌中通过水平基因转移获得了一些与人类定植和发病有关的基因外，人们对这些蛋白的性质甚至调控基因的数量知之甚少。研究者实验室最近的实验表明，ToxR和ToxS影响深海细菌深光杆菌菌株SS9对压力变化的反应能力和在高压下生长的能力。此外，在这种生物体中，ToxR/S与环AMP受体蛋白（CRP）一起调节不饱和脂肪酸（UFA’S）的水平。以前已经提出，UFA可能是膜适应高压和低温的重要因素。在这个项目中，研究者将在SS9中描述一般的ToxR/S调节，特别是UFA的压力和温度调节。在高压环境下，毒素rs基因表达与生长抑制之间的关系将得到澄清。将使用遗传和分子筛选策略鉴定ToxR/S调节基因。然后对这些基因的一个子集进行测序，对其转录调控进行表征，并通过突变研究确定其功能。进一步的研究将专门探讨压力和温度对UFA的转录、翻译和翻译后调控的可能性。在各种调节蛋白突变背景下，其产物控制顺式异丙酸和二十碳五烯酸水平的基因的转录调节将被确定为温度和压力的函数。最后，0-酮酰基- acp合成酶II的活性调控将通过动力学分析进行研究，该合成酶是高压和低温调节顺式异丙酸水平所必需的。尽管深海是地球上发现生命的最大部分，但人们对生物如何适应这种寒冷的环境知之甚少，这里的水压可以超过每平方英寸15,000磅。在这个项目中，一种从海底分离出来的细菌将被用于遗传和生理实验，以解决在低温和高压下生长和生存所需的膜成分（不饱和脂肪酸）的控制问题。将探索这种微生物中负责制造不饱和脂肪酸的酶是否具有使其适合深海条件的独特特性。研究者将寻找帮助机体适应高压的其他细胞功能。这些结果将有助于理解生命对极端环境的适应，并将提供关于细胞如何维持适当的膜功能的新信息。