ULTRAVIOLET DAMAGE REPAIR IN BACILLUS SUBTILIS SPORE DNA

遗传物质不断受到太阳紫外线的照射 辐射（紫外线），生物体高度重视 校正潜在的致死性或诱变性UV诱导的DNA损伤。它 长期以来，人们都知道患有相对罕见的 遗传性DNA修复疾病如着色性干皮病 过敏和皮肤癌高发。最近的 观测到的陆地紫外线暴露增加之间的相关性， 大气臭氧破坏，以及人类皮肤 癌症，强调研究基础的健康相关意义 细胞修复紫外线对其DNA损伤的机制。 芽孢杆菌属和梭菌属的细菌产生孢子， 对紫外线的抵抗力比植物生长高10-100倍 细胞细菌孢子的紫外线抗性是由于（i）独特的 孢子DNA的光化学和（ii）萌发孢子的能力， 准确修复这种独特的DNA损伤，称为“孢子光产物”， 或SP，通过使用两个主要的修复系统，其中一个显然是 现有的证据强烈暗示， 孢子形成过程中B型和A型之间的DNA螺旋， 在生产和随后的SP修复发芽。 这个项目的长期目标是阐明结构， 芽孢杆菌SP特异性DNA修复系统的调控及机制 枯草芽孢杆菌，称为SPL。自提交第一份申请以来，DNA 校正spl系统中的突变已经被克隆，定位在B上。 spl基因序列编码40 在目前的序列数据库中没有同源物的千道尔顿蛋白。的 本申请修订版的目标是： SPL基因的顺式作用调节位点和相应的 反式作用因子;研究这些调节成分 相互作用，以指导正确的时间和房室表达的 孢子形成过程中的基因;鉴定和纯化酶 参与SP修复，并克隆可能的其他spl基因;以及 研究SP修复反应的机理和要求， 体外，使用纯化的组分。

The genetic material is constantly subjected to solar ultraviolet radiation (UV), and living organisms place a high priority on the correction of potentially lethal or mutagenic UV-induced DNA damage. It has long been known that individuals afflicted with relatively rare heritable DNA repair disorders such as xeroderma pigmentosum exhibit UV hypersensitivity and a high incidence of skin cancer. More recently, the observed correlation between increased terrestrial UV exposure due to atmospheric ozone destruction, and an increasing incidence of human skin cancer, highlight the health-related significance of studying basic mechanisms by which cells repair UV damage to their DNA. Bacteria of the genera Bacillus and Clostridium produce spores which are 10-100 fold more resistant to killing by UV than vegetatively growing cells. UV resistance of bacterial spores is due to (i) the unique photochemistry of spore DNA and (ii) the ability of germinating spores to accurately repair this unique DNA damage, known as "spore photoproduct", or SP, by using two major repair systems, one of which is apparently specific for SP. The available evidence strongly implicates shifting of the DNA helix between the B-form and an A-like form during sporulation and germination in the production and subsequent repair of SP. The long-range objective of this project is to elucidate the structure, regulation, and mechanism of the SP-specific DNA repair system in Bacillus subtilis called spl. Since submission of the first application, DNA correcting a mutation in the spl system has been cloned, mapped on the B. subtilis chromosome, and sequenced; the spl gene sequence encodes a 40 kilodalton protein with no homolog in the current sequence databases. The objectives of this revised version of the application are: identifying both the cis-acting regulatory sites of the spl gene(s) and corresponding trans-acting factors; investigating how these regulatory components interact to direct the proper temporal and compartmental expression of the gene(s) during sporulation; identifying and purifying the enzyme(s) involved in SP repair, and cloning possible additional spl genes; and studying the mechanism and requirements of the SP repair reaction in vitro, using purified components.