Mechanism of Bacterial SMC Complex MukBEF

描述（申请人提供）：染色质结构经过标记， 严格控制细胞周期中的变化。维持适当的染色质 结构对于忠实地执行这些基本事件至关重要， 染色体复制、重组、基因表达或细胞分裂。错误 在任何一个过程中，通常都会导致基因组的不稳定性和染色体 可能导致致癌或发育缺陷的改变。 然而，染色质动力学的分子机制仍然主要是 未知SMC蛋白家族是一组新兴的细胞ATP酶 负责生物体中大规模的染色质重组， 细菌对人类这些蛋白质涉及如此多的范围， 细胞功能如染色体凝聚和浓缩，DNA修复和 剂量补偿最近发现，13 S凝聚的机理， 非洲爪蟾SMC复合体负责细胞内染色体浓缩 分裂，涉及大规模DNA的直接ATP依赖性变形 结构这是一种全新的酶活性。这个项目 重点是进一步的机制表征SMC蛋白使用 MukBEF，一种13 S凝聚素的细菌类似物，作为模型蛋白。具体 本课题的主要目的是：（1）研究MukBEF的生物活性; (2)研究MukBEF对细胞周期的调控作用;（3）研究MukBEF对细胞周期的调控作用。 用电子显微镜观察MukBEF-DNA复合物的结构;（4）研究 使用单DNA操作技术通过MukBEF进行DNA变形。这些 研究预计将产生一个全面的计划，MukBEF催化的 反应这些数据将有助于我们了解细胞内的 MukBEF的功能，并将阐明SMC蛋白在大规模 染色质动力学

DESCRIPTION (provided by applicant): Chromatin structure undergoes marked, tightly controlled changes during the cell cycle. Maintaining proper chromatin structure is essential for faithful execution of such fundamental events as chromosome replication, recombination, gene expression or cell division. Errors in either of the processes often result in genomic instability and chromosomal alterations potentially leading to carcinogenesis or developmental defects. However molecular mechanisms underlying chromatin dynamics remain largely unknown. The SMC protein family is an emerging group of cellular ATPases responsible for large-scale chromatin reorganizations in organisms ranging from bacteria to humans. These proteins have been implicated in such diverse range of cellular functions as chromosome cohesion and condensation, DNA repair and dosage compensation. It was found recently that the mechanism of 13S condensin, a Xenopus SMC complex responsible for the chromosome condensation during cell division, involves direct ATP-dependent deformation of the large-scale DNA structure. This is an entirely novel kind of enzymatic activity. This project focuses on further mechanistic characterization of the SMC proteins using MukBEF, a bacterial analog of 13S condensin, as a model protein. The specific aims of this project are: (1) characterize biochemical activities of MukBEF; (2) investigate cell cycle regulation of MukBEF; (3) investigate the architecture of MukBEF-DNA complex using electron microscopy; (4) investigate DNA deformation by MukBEF using single DNA manipulation technique. These studies are expected to yield a comprehensive scheme of the MukBEF-catalyzed reaction. These data will contribute to our understanding of the intracellular functions of MukBEF and will illuminate the role of SMC proteins in large scale chromatin dynamics.