MOLECULAR MECHANISMS OF DNA REPAIR AND RECOMBINATION IN YEAST

酵母 DNA 修复和重组的分子机制

• 批准号: 3777555
• 负责人: M A RESNICK
• 金额: --
• 依托单位: NATIONAL INSTITUTE OF ENVIRONMENTAL HEALTH SCIENCES
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/3777555
• 关键词: DNA damage; DNA directed DNA polymerase; DNA repair; DNA replication; Saccharomyces cerevisiae; chromosome aberrations; fungal genetics; gene deletion mutation; gene expression; gene induction /repression; genetic recombination; meiosis; nuclease

We are investigating the unique chromosomal metabolic events associated with meiosis and the repair of chromosomes following exposure to DNA damaging events in the yeast Saccharomyes cerevisiae. Many of the genes necessary for the repair of DNA double strand breaks (DSB) are required for the successful completion of the meiotic cycle suggesting that both processes proceed through similar molecular mechanisms. A central component for both the repair of DSBs and the successful completion of meiosis is the protein encoded by the RAD52 gene. In addition to its role in DSB repair and meiosis, RAD52 appears to influence spontaneous mitotic recombination. In strains carrying a complete deletion of the RAD52 gene mitotic recombination between repeats is reduced; however, this decrease is blocked by a concomitant mutation in the gene encoding the Rho-associated nuclease RhoNUC (RNC1). This result suggests that RNC1 is epistatic to RAD52 for spontaneous mitotic recombination. Interestingly rnc1 does not rescue the DSB repair deficiency or the meiotic lethality associated with rad52. The possible role of RAD52 during replication is also being investigated. Using a unique system whereby we measure the frequency of "excision" of a bacterial transposon Tn5 placed into the yeast LYS2 gene, we have found that mutations in the gene encoding DNA polymerase I or III lead to high levels of Tn5 "excision". The elevated levels of "excision" seen in polIII or polI strains is reduced when a null mutant of RAD52 is introduced into these strains. This suggests an interaction between the enzymes proposed to be responsible for DNA lagging strand synthesis and RAD52. RNC1 does not appear to play a role in this interaction since rnc1 rad52 polIII mutants are still blocked for Tn5 "excision".

我们正在调查与此相关的独特的染色体代谢事件 与减数分裂和接触DNA后染色体的修复有关 酿酒酵母中的破坏性事件。许多基因 是修复DNA双链断裂所必需的 对于减数分裂周期的成功完成，表明两者 这一过程通过类似的分子机制进行。一个中环 用于DSB修复和成功完成的组件 减数分裂是由RAD52基因编码的蛋白质。 除了在DSB修复和减数分裂中的作用外，RAD52似乎还 影响有丝分裂自发重组。在携带A基因的菌株中 重复序列间RAD52基因有丝分裂重组的完全缺失 减少；然而，这种减少被伴随的突变所阻止 在编码Rho相关核酸酶RhoNUC(RNC1)的基因中。这 结果表明，RNC1对RAD52的自发有丝分裂具有上位性作用 重组。有趣的是，rnc1并没有挽救DSB修复 缺乏或与rad52相关的减数分裂致死性。 RAD52在复制过程中的可能作用也正在研究中。 使用一种独特的系统，通过该系统我们可以测量 我们在酵母LYS2基因中发现了一个细菌转座子Tn5 编码DNA聚合酶I或III的基因突变会导致高 TN5水平的“切除”。中所见的高水平的手术切除 当RAD52的零突变是 被引入这些菌株。这表明， 酶被认为是负责DNA滞后链合成和 RAD52。RNc1似乎不在这种相互作用中起作用，因为 Rnc1rad52polIII突变体仍被阻止进行TN5“切除”。