Investigating the interplay between SMC complexes and Topoisomerase II

研究 SMC 复合物和拓扑异构酶 II 之间的相互作用

• 批准号: BB/S001425/1
• 负责人: Jonathan Baxter
• 金额: $ 61.93万
• 依托单位: University of Sussex
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2018
• 资助国家: 英国
• 起止时间: 2018 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=BB%2FS001425%2F1
• 关键词: Investigating; interplay; between; SMC; complexes

DNA is the repository for all the genetic information of a cell. To encode all this information DNA molecules are extraordinarily long. For example, a human cell contains nearly 2m of DNA in a nucleus smaller than 20 microns in diameter. Not only must all this DNA be packed into the nucleus but its organisation must be constantly re-organised so that its packaging can promote normal gene expression during most of the cell cycle before being tightly packaged during mitosis in a manner that allows faithful segregation of all chromosomes to daughter cells. Failure to appropriately organise chromosomes during the different stages of the cell cycle leads to chromosome fragility, aberrant chromosome numbers and cell death. Features often associated with cancer, ageing and human growth disorders.Two types of protein complexes appear to be essential to establish and maintain chromosomal organisation, SMC complexes and type II topoisomerases (Top2). The ancient family of SMC complexes are found in all the kingdoms of life, where they are required to appropriately structure chromosomes for genetic inheritance. Both the eukaryotic SMC complexes cohesin and condensin are thought to organise chromosomes by promoting DNA looping along chromosomes. Type II topoisomerases are also found in all cell types where they are thought to organize DNA by allowing one section of DNA to pass through another, promoting untangling of chromosomes and relaxing any DNA topological stress that builds up on the DNA. The eukaryotic type II topoisomerase Top2 is proposed to have both an enzymatic and structural role in chromosome structure. However, analysis to date of how SMC complexes and Top2 may work together to dynamically organise chromosome structure has produced seemingly contradictory results. Some of these studies indicate that SMC complexes and Top2 work in concert with each other to promote proper gene expression and chromosome segregation. However, others have found that they can also operate independently or even antagonistically in the maintenance of normal chromosome structure. These contrasting results indicate a complex and potentially context dependent interplay between Top2 and the different SMC complexes. Understanding the nature of this interplay is crucial for how these two ancient DNA manipulating machines work together to organise DNA and ensure normal biological function. Indeed, mutations in the genes encoding Top2 and SMC proteins are closely linked with cancer progression and the growth of animals and plants. In this proposal, we will investigate the interplay and co-dependencies of SMC complexes and Top2 on chromosome structure. Recently we have used the Hi-C chromosome conformation technique to show that cohesin and condensin organise the structure of budding yeast chromosomes in distinct ways. Here, we will examine how chromosome structure is altered by Top2 and how such changes are regulated by the different SMC complexes cohesin and condensin. We will go onto to examine if Top2 dependent changes to chromosome structure require the enzymatic activity of Top2 or only its binding to chromosomes and if these are regulated by SMC complexes. Finally, we will examine if DNA supercoiling and its regulation by Top2, and potentially SMCs, organizes chromosomes.Together this proposal aims to provide a comprehensive and coherent analysis of how the fundamental DNA structuring activities of Top2 and the SMC complexes cohesin and condensin interact to generate functional chromosome structure.

DNA是细胞所有遗传信息的存储库。为了编码所有这些信息，DNA分子非常长。例如，人类细胞在小于20微米的直径小于20微米的核中含有近2M的DNA。不仅必须将所有这些DNA包装到核中，而且必须不断地重新组织其组织，以便其包装可以在大多数细胞周期中促进正常基因表达，然后以有丝分裂的方式紧密包装，以使所有染色体忠实地隔离到子细胞中。在细胞周期的不同阶段，未能适当组织染色体会导致染色体脆弱性，异常染色体数和细胞死亡。通常与癌症，衰老和人类生长障碍相关的特征。两种蛋白质复合物的类型对于建立和维持染色体组织，SMC复合物和II型拓扑异构酶（TOP2）似乎至关重要。古老的SMC综合体系列是在生活的所有王国中都发现的，在那里，它们被要求适当地构造染色体以进行遗传遗传。真核SMC复合物粘着素和冷凝素都被认为通过促进沿染色体循环的DNA循环来组织染色体。在所有细胞类型中还发现了II型拓扑异构酶，它们被认为通过允许一部分DNA通过另一个细胞来组织DNA，从而促进染色体的无缠结并放松在DNA上累积的任何DNA拓扑应力。提出真核II型拓扑异构酶TOP2在染色体结构中既具有酶促和结构的作用。但是，迄今为止，SMC复合物和TOP2如何共同组织染色体结构的分析产生了看似矛盾的结果。其中一些研究表明，SMC复合物和TOP2相互协同起作用，以促进适当的基因表达和染色体分离。但是，其他人发现它们也可以在维持正常染色体结构的情况下独立甚至拮抗。这些对比结果表明TOP2和不同SMC复合物之间的复杂且潜在的背景相互作用。了解这种相互作用的性质对于这两个古老的DNA操纵机器如何共同组织DNA并确保正常的生物学功能至关重要。实际上，编码TOP2和SMC蛋白的基因中的突变与癌症进展以及动物和植物的生长密切相关。在此提案中，我们将研究SMC复合物的相互作用和共同依赖性，而TOP2在染色体结构上。最近，我们使用了HI-C染色体构象技术来表明粘蛋白和冷凝蛋白以不同的方式组织出萌芽的酵母染色体的结构。在这里，我们将研究如何通过TOP2改变染色体结构，以及如何通过不同的SMC复合物粘着蛋白和冷凝素调节这种变化。我们将继续检查染色体结构的TOP2依赖性变化是否需要TOP2的酶促活性，或仅需要其与染色体的结合，以及它们是否由SMC复合物调节。最后，我们将检查DNA超螺旋及其对TOP2的调节以及潜在的SMC组织是否组织染色体。该提案旨在对TOP2的基本DNA结构活动和SMC ComplexS中的基本DNA结构活动进行全面而连贯的分析，以使SMC Copplecion如何凝聚蛋白和公寓相互作用以产生功能性染色体结构。

项目成果

Cryo-EM structure of the Smc5/6 holo-complex

• DOI: 10.1101/2021.11.25.470006
• 发表时间: 2021-11-25
• 期刊: bioRxiv
• 作者: Hallett, S. T.;Campbell Harry, I.;Oliver, A. W.
• 通讯作者: Oliver, A. W.

Checkpoint inhibition of origin firing prevents DNA topological stress.

原点激发的检查点抑制可防止 DNA 拓扑应力。

• DOI: 10.1101/gad.328682.119
• 发表时间: 2019
• 期刊: Genes & development
• 影响因子: 10.5
• 作者: Morafraile EC

Principles of meiotic chromosome assembly revealed in S. cerevisiae

• DOI: 10.1038/s41467-019-12629-0
• 发表时间: 2019-10
• 期刊: Nature Communications
• 影响因子: 16.6
• 作者: S. Schalbetter;G. Fudenberg;J. Baxter;K. Pollard;Matthew J. Neale

Telomerase subunit Est2 marks internal sites that are prone to accumulate DNA damage.

• DOI: 10.1186/s12915-021-01167-1
• 发表时间: 2021-11-20
• 期刊: BMC biology
• 影响因子: 5.4
• 作者: Pandey S;Hajikazemi M;Zacheja T;Schalbetter S;Neale MJ;Baxter J;Guryev V;Hofmann A;Heermann DW;Juranek SA;Paeschke K
• 通讯作者: Paeschke K