NUV RESISTANCE-- FUR-DEPENDENT REGULATION OF RPOS.

全球平流层臭氧保护层的损耗正在导致到达地球表面的近紫外线辐射（UVB-290-320 nm）水平上升。人类也通过使用晒黑床暴露在紫外线辐射下。近紫外线辐射的增加被认为是皮肤癌发病率急剧上升的原因。本实验室的总体目标是确定与近紫外线辐射损伤、保护和恢复有关的特定生物学机制。大肠杆菌将作为模式生物来研究控制铁摄取的基因（铁摄取调节因子；fur）和固定相sigma因子（rpoS）之间的关系。RpoS是细菌抵御近紫外光（NUV; 290-400 nm）的核心调控成分。氢过氧化物酶，HPI和HPII，是RpoS规则的成员。本研究的具体目的是确定Fur和RpoS相互作用的水平，以调节细胞对紫外线照射和其他应激的反应。如果Fur蛋白在rpoS调控的铁依赖性激活中起关键作用，那么影响铁的摄取、释放和利用的突变体将是确定铁摄取和供应途径中影响rpoS活性的位置的绝佳遗传工具。本研究还将确定Fur蛋白是否参与调节过氧化氢酶活性的氧依赖途径。过氧化氢酶活性将在细胞生命的不同阶段进行测定。利用已知在细胞生命周期的不同阶段调节HPI和HPII的oxyR和rpoS突变株，我们将能够确定Fur在平稳期和指数期对HPI和HPII水平的影响。铁可用性对HPI和HPII过氧化氢酶活性水平的影响将在富铁和缺铁培养基中确定。转录水平的调控将通过rpoS::lacZ和katG::lacZ和katE::lacZ启动子融合进行。总的来说，这项研究将有助于确定其他调节RpoS活性的细胞条件和基因，并揭示调节过氧化氢酶合成的复杂机制和其他细胞防御NUV辐射的机制。本研究将为入读视光与药学专业预科的本科生提供研究训练机会。

The depletion of the global stratospheric ozone shield is leading to a rise in the level of near-ultraviolet radiation (UVB-290-320 nm) reaching the earth's surface. Humans are also exposed to NUV radiation through the use of tanning beds. Increases in near-ultraviolet radiation are believed to be responsible for the dramatic rise in the incidence of skin cancer.: The overall objective of this lab is to identify specific biological mechanisms involved in the damage, protection and recovery from near- ultraviolet radiation. Escherichia coli will be used as a model organism to investigate the relationship between the genes that controls iron uptake (ferric uptake regulator; fur) and the stationary-phase sigma factor (rpoS). RpoS is a central regulatory component in bacteria for the defense against near-ultraviolet light (NUV; 290-400 nm). Hydroperoxidases, HPI and HPII, are members of the RpoS regulon. The specific aim of this study is to determine the levels at which Fur and RpoS interact to regulate cellular response to NUV irradiation and other stresses. If the Fur protein plays a key role in iron-dependent activation of rpoS regulon, mutants that affect the uptake, release and utilization of iron will be excellent genetic tools to determine the locations in the iron uptake and supply pathways that influence rpoS activity. This study will also determine whether the Fur protein is involved in an oxyR- dependent pathway regulating catalase activity. Catalase activity will be assayed at different phases of the cell's life. Utilizing oxyR and rpoS mutant strains that are known to regulate HPI and HPII at different stages of the cell's life cycle, we will be able to determine the role of Fur in contributing to the levels of HPI and HPII during both stationary and exponential phases. The effect of iron availability on the activity levels of HPI and HPII catalase will be determined in iron-rich and iron- deficient media. Regulation at the transcriptional level will be conducted using rpoS: :lacZ and katG::lacZ and katE: :lacZ promoter fusions. Overall this study will help identify other cellular conditions and genes that regulate RpoS activity, and unravel the complex mechanisms that regulate catalase synthesis and other cellular defense mechanisms against NUV radiation. This research will provide training opportunities in research for undergraduate students enrolled in pre-professional programs in optometry and pharmacy.