SGER: Apoptosis in Bacteria

SGER：细菌细胞凋亡

• 批准号: 0132889
• 负责人: Kim Lewis
• 金额: $ 5万
• 依托单位: Northeastern University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-09-01 至 2003-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0132889&HistoricalAwards=false
• 关键词: SGER; Apoptosis; Bacteria

When a bacterial cell dies, the cause of death is often autolysis, rather than direct damage produced by a harmful factor. Hydrolysis of peptidoglycan is a necessary stage in cell wall synthesis, and autolysis has been viewed as a result of "disbalance between peptidoglycan synthesis and hydrolysis", essentially a maladaptive mistake. This project explores the hypothesis that autolysis is not a mistake, but adaptive programmed death. Autolysis is part of the developmental process of fruiting body formation and sporulation in Myxococcus. Autolysis which is required for natural transformation in S. pneumoniae is another example of specialized adaptive programmed death. Bacteria show many features of complex organization, similar to multicellular organisms. Like in multicellular species, a bacterial population would benefit from eliminating defective cells. The aim of this project is to test the feasibility of the idea that autolysis is the mechanism of adaptive apoptosis in bacteria. Specifically, a search for regulatory components of a possible apoptotic pathway linking particular types of cell damage to activation of autolysins is being undertaken. A genetic approach is being used to identify putative apoptotic genes. E. coli will be mutagenized with mini-Tn10 transposon and selected for survival to lethal levels of a mutagen; and high temperature. Mutants that show resistance to killing (but not resistance to growth in the presence of) both factors will become candidates for being affected in genes coding for apoptotic compounds. "Random" PCR will be used to identify the flanking DNA regions, amplified DNA will be sequenced by single passage, and the genes carrying the Tn insertions will be identified using the database of the E. coli genome. The mutants will also be characterized phenotypically using a panel of different lethal factors. Strains with known mutations, such as those lacking autolysins, will also be tested for possible survival with the panel of lethal factors. This exploratory project will show whether E. coli has regulatory genes affecting autolysis and will lay the basis for future detailed studies of apoptosis in bacteria.

当细菌细胞死亡时，死亡的原因往往是自溶，而不是由有害因素产生的直接损伤。肽聚糖的水解是细胞壁合成的必要阶段，自溶被认为是“肽聚糖合成与水解失衡”的结果，本质上是一种不适应错误。这个项目探讨的假设，自溶不是一个错误，而是适应性程序性死亡。自溶是粘球菌子实体形成和产孢发育过程的一部分。肺炎链球菌自然转化所需的自溶是另一个特殊适应性程序性死亡的例子。细菌表现出许多复杂组织的特征，类似于多细胞生物。就像在多细胞物种中一样，细菌种群将从消除缺陷细胞中受益。这个项目的目的是测试自溶是细菌适应性凋亡机制的可行性。具体来说，研究人员正在寻找一种可能的凋亡途径的调节成分，这种途径将特定类型的细胞损伤与自溶素的激活联系起来。一种遗传学方法被用来鉴定假定的凋亡基因。大肠杆菌将被mini-Tn10转座子诱变并被选择存活到致死性诱变剂水平；和高温。显示出对杀伤（但在存在这两种因素的情况下对生长没有抵抗力）的突变体将成为编码凋亡化合物的基因受到影响的候选者。“随机”PCR将用于鉴定侧翼DNA区域，扩增的DNA将通过单通道测序，携带Tn插入的基因将使用大肠杆菌基因组数据库进行鉴定。突变体也将被表征表型使用一组不同的致死因素。具有已知突变的菌株，如缺乏自溶素的菌株，也将在致命因素小组中进行可能的存活测试。该探索性项目将揭示大肠杆菌是否存在影响自溶的调控基因，为今后细菌细胞凋亡的详细研究奠定基础。