Hauptman Woodward Institute, Buffalo, NY 14203, USA.
J Mol Biol. 2011 Nov 11;413(5):901-7. doi: 10.1016/j.jmb.2011.08.002. Epub 2011 Aug 3.
The bacterial chromosome trafficking apparatus or the segrosome participates in the mitotic-like segregation of the chromosomes prior to cell division in several bacteria. ParB, which is the parS DNA-binding component of the segrosome, polymerizes on the parS-adjacent chromosome to form a nucleoprotein filament of unknown nature for the segregation function. We combined static light scattering, circular dichroism and small-angle X-ray scattering to present evidence that the apo form of the mycobacterial ParB forms an elongated dimer with intrinsically disordered regions as well as folded domains in solution. A comparison of the solution scattering of the apo and the parS-bound ParBs indicates a rather drastic compaction of the protein upon DNA binding. We propose that this binding-induced conformational transition is priming the ParB for polymerization on the DNA template.
细菌染色体运输装置或 segrosome 参与了几种细菌在细胞分裂前的类似于有丝分裂的染色体分离。ParB 是 segrosome 的 parS DNA 结合成分，在 parS 相邻的染色体上聚合，形成一种未知性质的核蛋白丝，用于分离功能。我们结合静态光散射、圆二色性和小角 X 射线散射，证明了无配体形式的分枝杆菌 ParB 在溶液中形成具有固有无序区域和折叠结构域的拉长二聚体。apo 和 parS 结合的 ParB 的溶液散射比较表明，在 DNA 结合时，蛋白质发生了相当大的压缩。我们提出，这种结合诱导的构象转变为 ParB 在 DNA 模板上的聚合做好了准备。
