Bacterial Response to Singlet Oxygen

细菌对单线态氧的反应

• 批准号: 7145773
• 负责人: TIMOTHY J DONOHUE
• 金额: $ 26.72万
• 依托单位: UNIVERSITY OF WISCONSIN-MADISON
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-08-01 至 2010-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7145773
• 关键词: DNA directed RNA polymerase; Rhodospirillales; bacteria characteristic; bacterial genetics; cell membrane; cytogenetics; cytoprotection; cytotoxicity; genetic transcription; microorganism culture; protein localization; protein protein interaction; protein structure function; singlet oxygen; transcription factor; zinc

DESCRIPTION (provided by applicant): Molecular oxygen (O2) is critical to life on this planet; it is a product of oxygenic photosynthesis and it is a substrate for bioenergetic pathways like aerobic respiration. While O2 is relatively inert, it is converted to different chemical classes of toxic reactive oxygen species by either one electron transfer or energy transfer reactions. When single electrons are transferred to O2, it is reduced to superoxide, hydrogen peroxide, or hydroxyl radicals. When energy is transferred to O2, singlet oxygen ([1]O2) is formed. We have considerable information about how cells respond to superoxide, hydrogen peroxide and hydroxyl radicals. However, relatively little is known about how cells respond to [1]O2, a common reactive oxygen species that can destroy the integrity of bioenergetic membranes, damage many biomolecules, generate mutations, or kill cells. To rectify this situation, we will study the bacterial response to [1]O2. Our experiments capitalize on what is known about the formation and response to conditions that generate [1]O2 in the alpha-proteobacterium Rhodobacter sphaeroides. This is the biological system of choice for studying this response since photosynthetic organisms like R. sphaeroides generate significant amounts of [1]O2 as a byproduct of solar energy capture. In addition, we have identified a transcriptional response to conditions that generate [1]O2 in this bacterium. This transcriptional response to [1]O2 depends on an alternative sigma factor in the extracytoplasmic function family, sigmaE, and the anti-sigma factor, ChrR. We have also obtained a 3-dimensional view of the sigmaE-ChrR complex that controls the transcriptional response to [1]O2. In this project, we will determine how the presence of [1]O2 increases sigmaE activity. [1]O2 is bacteriocidal to cells lacking sigmaE, so we will also identify gene products that protect cells from this toxic reactive oxygen species. The chemical properties of [1]O2 predict that the damage generated by this reactive oxygen species and the activities that function in this stress response will differ from those produced in the presence of superoxide, hydrogen peroxide or hydroxyl radicals. Analysis of microbial genome sequences indicates that homologs of R. sphaeroides sigmaE and ChrR are present in many photosynthetic bacteria plus non-photosynthetic bacteria that are likely to encounter [1]O2 generated by other pathways as part of plant and animal defenses against pathogenic microbes. Thus, our research will answer important questions about the ability of many cells to sense and protect themselves from [1]O2 and the nature of the modifications caused by [1]O2 to proteins and other biomolecules. The use of [1]O2 by eukaryotic cells to defend against pathogenic microbes and in photodynamic therapy to kill cancer cells predicts that our findings will have large antimicrobial and therapeutic potential.

描述（由申请人提供）：分子氧（O2）对这个星球上的生命至关重要；它是充氧光合作用的产物，是有氧呼吸等生物能途径的底物。尽管O2相对惰性，但它通过一种电子转移或能量转移反应转化为不同化学类别的有毒活性氧。当单个电子转移到O2时，将其还原为超氧化物，过氧化氢或羟基自由基。当能量转移到O2时，形成单线氧（[1] O2）。我们拥有有关细胞如何对超氧化物，过氧化氢和羟​​基自由基的反应的大量信息。然而，对于细胞如何反应[1] O2，这是一种可以破坏生物能膜的完整性，损害许多生物分子，产生突变或杀死细胞的常见活性的常见氧o2的众所周知。为了纠正这种情况，我们将研究对[1] O2的细菌反应。我们的实验利用了对在α-杆菌rohodobacter sphaeroides中产生[1] o2的形成和响应的了解。这是研究这种反应的首选生物学系统，因为R. sphaeroides（如R. sphaeroides）的光合生物会产生大量的[1] O2作为太阳能捕获的副产品。此外，我们已经确定了对在该细菌中产生[1] O2的条件的转录反应。对[1] O2的转录响应取决于外质功能家族中的替代Sigma因子，Sigmae和抗Sigma因子Chrr。我们还获得了Sigmae-CHRR复合物的3维视图，该络合物控制了对[1] O2的转录响应。在这个项目中，我们将确定[1] O2的存在如何增加Sigmae活性。 [1] O2是缺乏sigmae细胞的细胞杀虫剂，因此我们还将确定保护细胞免受这种有毒活性氧的基因产物。 [1] O2的化学特性预测，这种活性氧产生的损害以及在这种应力反应中起作用的活性与在存在超氧化物，过氧化氢或羟基自由基的情况下产生的损伤将有所不同。对微生物基因组序列的分析表明，许多光合细菌以及可能遇到的非光合合成细菌的Sphaeroides Sigmae和ChrR的同源物存在于其他途径产生的[1] O2 [1]中，这是植物和动物防御症的一部分。因此，我们的研究将回答有关许多细胞感知和保护自己免受[1] O2的能力以及由[1] O2对蛋白质和其他生物分子引起的修饰的性质的重要问题。真核细胞使用[1] O2来防御致病性微生物和光动力疗法来杀死癌细胞，预测我们的发现将具有较大的抗菌和治疗潜力。