Nucleoid-associated proteins (NAPs) are DNA binding proteins critical for the organization and function of the bacterial chromosome. A newly discovered NAP in Caulobacter crescentus, GapR, is thought to facilitate the movement of the replication and transcription machines along the chromosome by stimulating type II topoisomerases to remove positive supercoiling. Here, utilizing genetic, biochemical, and biophysical studies of GapR in light of a recently published DNA-bound crystal structure of GapR, we identified the structural elements involved in oligomerization and DNA binding. Moreover, we show that GapR is maintained as a tetramer upon its dissociation from DNA and that tetrameric GapR is capable of binding DNA molecules in vitro. Analysis of protein chimeras revealed that two helices of GapR are functionally conserved in H-NS, demonstrating that two evolutionarily distant NAPs with distinct mechanisms of action utilize conserved structural elements to oligomerize and bind DNA.

中文翻译：

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类核相关蛋白 GapR 使用保守的结构元素来寡聚化和结合 DNA。

类核相关蛋白 (NAP) 是对细菌染色体的组织和功能至关重要的 DNA 结合蛋白。在新月形茎杆菌中新发现的 NAP GapR 被认为通过刺激 II 型拓扑异构酶去除正超螺旋来促进复制和转录机器沿染色体的运动。在这里，根据最近发表的 GapR 的 DNA 结合晶体结构，利用 GapR 的遗传、生化和生物物理研究，我们确定了参与寡聚化和 DNA 结合的结构元素。此外，我们表明 GapR 在与 DNA 解离后保持为四聚体，并且四聚体 GapR 能够在体外结合 DNA 分子. 对蛋白质嵌合体的分析表明，GapR 的两个螺旋在 H-NS 中是功能保守的，这表明具有不同作用机制的两个进化距离较远的 NAP 利用保守的结构元件来寡聚化和结合 DNA。