Mechanism of Bacterial SMC Complex MukBEF

描述(申请人提供)：染色质结构经过标记， 在细胞周期中严格控制变化。保持适当的染色质 结构对于忠实地执行基本事件是必不可少的，例如 染色体复制、重组、基因表达或细胞分裂。错误 在这两个过程中的任何一个过程中通常会导致基因组不稳定和染色体 可能导致癌变或发育缺陷的改变。 然而，染色质动力学背后的分子机制在很大程度上仍然存在 未知。SMC蛋白家族是一组新兴的细胞ATPase 负责生物中大规模的染色质重组，范围从 细菌传给人类。这些蛋白质涉及的范围如此之广 细胞功能如染色体凝聚和凝聚，DNA修复和 剂量补偿。最近发现，13S凝集素的作用机制是， 一种与细胞内染色体凝聚有关的非洲爪哇SMC复合体 分裂，涉及依赖于ATP的大规模DNA的直接变形 结构。这是一种全新的酶活性。这个项目 重点研究了SMC蛋白的进一步的机械特性 MukBEF，一种13S凝集素的细菌类似物，作为模型蛋白。具体的 本项目的目标是：(1)研究MukBEF的生化活性； (2)研究MukBEF对细胞周期的调控；(3)研究MukBEF对细胞周期的影响。 MukBEF-DNA复合体的电子显微镜构筑；(4)研究 MukBEF使用单DNA操作技术进行DNA变形。这些 预计研究将产生MukBEF催化的全面方案 反应。这些数据将有助于我们理解细胞内的 MukBEF的功能，并将阐明SMC蛋白在大规模中的作用 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.