PROKARYOTIC GENE REGULATION BY LIGHT AND OXYGEN

PI的实验室最近发现了五种反式调控 调控原核生物基因表达的因子对基因表达的影响 氧分压和光照强度。在拟议的筹资期间， 这些调控因素中的每一个都将是遗传和生化的 以它们在控制基因表达方面的作用为特征 氧气和光。两种“氧气响应”调节蛋白含有 序列基序表明它们是跨膜的传感器激酶 通过DNA的磷酸化来传递关于厌氧菌的信息 约束性反应调节剂。这些传感器激酶中的每一个都有序列 表明它们可能参与形成不稳定氧分子的基序 铁硫络合物。铁结合在激酶功能中的作用将是 对临界铁结合进行定点突变的探索 以及对分离的多肽进行EPR分析。这其中的一个 感受器蛋白(SenC)在结构上也与SCOI蛋白相似 已知参与细胞色素组装的酵母线粒体 C氧化酶。正如在酵母中观察到的那样，SenC的突变会导致减少 细胞色素c氧化酶的合成。应该指出的是，在人类中 未能正确合成具有功能的细胞色素C氧化酶复合体 与退行性疾病如帕金森氏症和 缺血性心脏病。另一种调节蛋白(HvrA)已经被 确定了哪些基因负责控制基因表达 对光照强度变化的反应。的感光能力 这种蛋白质将通过分析黄素结合能力进行分析。 HvrA。该实验室还在表征一种光传感调节装置 参与调控S-腺苷酶表达的蛋白质 同型半胱氨酸水解酶(SAHase)。在人类中，SAHase是一个重要的 腺苷细胞毒作用的促成因素导致 腺苷脱氨酶患者的严重免疫缺陷 缺乏症。

The PI's laboratory has recently identified five trans-acting regulatory factors governing prokaryotic gene expression in response to changes in oxygen tension and light intensity. During the proposed funding period, each of these regulatory factors will be genetically and biochemically characterized for their role in controlling gene expression in response to oxygen and light. Two "oxygen responding" regulatory proteins contain sequence motifs indicating that they are membrane spanning sensor kinases that transmits information about anaerobioses via phosphorylation of a DNA binding response regulator. Each of these sensor kinases have sequence motifs indicating that they may be involved in forming an oxygen labile iron sulfur complex. The role of iron binding in kinase function will be probed by performing site directed mutagenesis on critical iron binding ligands as well as by EPR analysis of isolated polypeptides. One of these sensor kinases (SenC) is also structurally similar to the ScoI protein in yeast mitochondria which is known to be involved in assembly of cytochrome c oxidase. As is observed in yeast, mutations in SenC leads to a reduction in cytochrome c oxidase synthesis. It should be noted that in humans the failure to properly synthesize a functional cytochrome c oxidase complex has been implicated in degenerative diseases such as Parkinson's and Ischemic heart disease. An additional regulatory protein (HvrA) has been identified which is responsible for controlling gene expression in response to changes in light intensity. The light sensing capabilities of this protein will be analyzed by assaying for flavin binding capabilities of HvrA. The laboratory is also characterizing a light sensing regulatory protein involved in controlling expression of the enzyme S-adenosyl homocysteine hydrolase (SAHase). In humans, SAHase is an important contributing factor in the cytotoxic effects of adenosine leading to severe immune deficiency in patents with adenosine deaminase (ADA) deficiency.