Maurer Sebastian, Fritz Jürgen, Muskhelishvili Georgi
Jacobs University, Campus Ring 1, 28759 Bremen, Germany.
J Mol Biol. 2009 Apr 17;387(5):1261-76. doi: 10.1016/j.jmb.2009.02.050. Epub 2009 Feb 28.
Bacterial nucleoid is a dynamic entity that changes its three-dimensional shape and compaction depending on cellular physiology. While these changes are tightly associated with compositional alterations of abundant nucleoid-associated proteins implicated in reshaping the nucleoid, their cooperation in regular long-range DNA organization is poorly understood. In this study, we reconstitute a novel nucleoprotein structure in vitro, which is stabilized by cooperative effects of major bacterial DNA architectural proteins. While, individually, these proteins stabilize alternative DNA architectures consistent with either plectonemic or toroidal coiling of DNA, the combination of histone-like protein, histone-like nucleoid structuring protein, and integration host factor produces a conspicuous semiperiodic structure. By employing a bottom-up in vitro approach, we thus characterize a minimum set of bacterial proteins cooperating in organizing a regular DNA structure. Visualized structures suggest a mechanism for nucleation of topological transitions underlying the reshaping of DNA by bacterial nucleoid-associated proteins.
细菌类核是一个动态实体，其三维形状和压缩程度会根据细胞生理状态而变化。虽然这些变化与参与重塑类核的丰富类核相关蛋白的组成改变紧密相关，但它们在常规长程DNA组织中的协同作用却知之甚少。在本研究中，我们在体外重建了一种新型核蛋白结构，该结构由主要细菌DNA结构蛋白的协同作用稳定。虽然这些蛋白单独作用时可稳定与DNA的麻花状或环形盘绕一致的不同DNA结构，但组蛋白样蛋白、类组蛋白核结构蛋白和整合宿主因子的组合产生了一种明显的半周期结构。通过采用自下而上的体外方法，我们由此表征了一组在组织规则DNA结构中协同作用的最小细菌蛋白集。可视化结构提示了一种细菌类核相关蛋白重塑DNA时拓扑转变成核的机制。
