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

BartlettToxR/S调节子在弧菌科细菌中广泛分布。然而，除了通过霍乱弧菌水平基因转移获得的一些与人类定植和致病相关的基因外，人们对这些蛋白调控的基因的性质甚至数量知之甚少。研究人员实验室最近的实验表明，ToxR和ToxS会影响深海细菌深发光杆菌SS9菌株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与环腺苷酸受体蛋白(CRP)一起似乎调节不饱和脂肪酸(UFA)的水平。以前有人认为，不饱和脂肪酸可能是膜适应压力升高和温度下降的重要因素。在这个项目中，调查者将描述ToxR/S规则的总体特征，特别是SS9中不饱和脂肪酸的压力和温度规则。加压下毒素受体基因表达与生长抑制之间的关系将被阐明。我们将采用遗传学和分子筛查相结合的方法来鉴定弓形虫毒素受体/S调控基因。然后将对这些基因的一个子集进行测序，确定它们的转录调控特征，并通过突变研究确定它们的功能。其他研究将专门探索压力和温度对不饱和脂肪酸转录、翻译和翻译后调节的可能性。在不同的调节蛋白突变背景下，其产物控制顺式疫苗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，将通过动力学分析来检验0-酮酰-ACP合成酶II的活性调节，这是高压和低温调节顺式疫苗酸水平所必需的。尽管深海是地球上发现生命的最大部分，但人们对生物对这种寒冷环境的适应知之甚少，在这种寒冷的环境中，水压可以超过每平方英寸15,000磅。在这个项目中，从海底分离的一种细菌将被用于遗传和生理实验，以解决其在低温高压下生长和生存所需的膜成分(不饱和脂肪酸)的控制。将探索这种微生物中负责制造不饱和脂肪酸的一种酶具有适合深海条件的独特特性的可能性。研究人员将寻求确定帮助生物体适应高压的额外细胞功能。这些结果将有助于理解生命对极端环境的适应，并将为细胞如何维持适当的膜功能提供新的信息。

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.