ELUCIDATING THE GLOBAL ARCHITECTURE OF THE BACTERIAL SEGROSOME

这个子项目是许多利用 由NIH/NCRR资助的中心赠款提供的资源。子项目和 研究者（PI）可能从另一个NIH来源获得了主要资金， 因此可以在其他CRISP条目中表示。所列机构为 研究中心，而研究中心不一定是研究者所在的机构。 结核病，特别是具有多重抗药性的结核病，与艾滋病一起，是一种严重的健康威胁。本研究的目的是了解结核分枝杆菌染色体分离体（ParABS）的ParB-DNA组装的三维结构。在细菌中，分离体是质粒和染色体分离所必需的。它由两个蛋白质组成，分别命名为帕拉和帕拉B，以及一组14-16个残基的回文DNA序列，parS，它们位于复制起点附近。 ParB在parS近端染色体DNA上聚集形成一个大的核蛋白组装体或分区复合体（覆盖> 1个DNA酶），在几种细菌中招募许多蛋白质，包括帕拉（驱动分离的ATP酶）、SMC（染色体凝聚蛋白）、MipZ（细胞分裂位点选择因子）和PopZ（细胞极组织因子）。关于这些细胞上层结构的三维组织知之甚少，这在本提案中得到了解决。 由于多结构域和多聚体性质，ParB及其复合物的结构表征具有挑战性。一个完整长度的染色体ParB以前从未被结晶。将使用溶液散射分析ParB分区复合物的结构组织，这是理解它如何刺激帕拉活性并在功能上与凝聚素相互作用，从而导致染色体分离和凝聚的垫脚石。 从Bio-SAXS站获得的ParB-DNA复合物上蔗糖对比度变化的溶液散射数据，以及其他实验数据（如福斯特共振能量转移，X射线足迹与质谱），将有助于建立低分辨率的segrosome组织模型。对比度变化将用于突出溶液散射衍生的分子包络内的双组分系统中的每个组分。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Tuberculosis, especially in its multi-drug resistant form and in combination with AIDS, is a serious health threat. The aim of this proposal is to understand three-dimensional organization of the ParB-DNA assembly of the chromosomal segrosome (ParABS) in Mycobacterium tuberculosis. The segrosome is required for plasmid and chromosome segregation in bacteria. It consists of 2 proteins, named ParA and ParB and a set of 14-16 residue palindromic DNA sequences, parS, which are found near the replication origin. ParB polymerize on the parS-proximal chromosomal DNA to form a large nucleoprotein assembly or the partition complex (covering > 1 kilobases of DNA) that recruit a number of proteins in several bacteria, including ParA (an ATPase that drives segregation), SMC (chromosome condensation protein), MipZ (cell division site selector) and PopZ (cell-pole organizing factor). Little is known about the three-dimensional organizations of these cellular superstructures, which is addressed in this proposal. Due to multi-domain and multimeric nature, structural characterization of ParB and its complexes is challenging. A full-length chromosomal ParB has never been crystallized before. Architectural organization of the ParB partition complex will be analyzed using solution scattering, which is a stepping-stone to understand how it stimulates ParA activity and functionally interacts with condensins, leading to chromosome segregation and condensation. Solution scattering data with sucrose contrast variation on the ParB-DNA complex obtained from Bio-SAXS station, together with other experimental data (such as Forster resonance energy transfer, X-ray footprinting with mass spectrometry), will assist in building low-resolution model of segrosome organization. Contrast variations will serve to highlight each component in a two-component system within the solution scattering-derived molecular envelope.