Cnu 突变研究揭示了 Cnu 和 H-NS 之间的吸引力。
A mutational study of Cnu reveals attractive forces between Cnu and H-NS.
机构信息
Department of Biology, College of Biological Sciences and Biotechnology, Chungnam National University, Daejeon, 305-764, Korea.
出版信息
Mol Cells. 2012 Feb;33(2):211-6. doi: 10.1007/s10059-012-0006-5. Epub 2012 Feb 15.
Cnu is a small 71-amino acid protein that complexes with H-NS and binds to a specific sequence in the replication origin of the E. coli chromosome. To understand the mechanism of interaction between Cnu and H-NS, we used bacterial genetics to select and analyze Cnu variants that cannot complex with H-NS. Out of 2,000 colonies, 40 Cnu variants were identified. Most variants (82.5%) had a single mutation, but a few variants (17.5%) had double amino acid changes. An in vitro assay was used to identify Cnu variants that were truly defective in H-NS binding. The changes in these defective variants occurred exclusively at charged amino acids (Asp, Glu, or Lys) on the surface of the protein. We propose that the attractive force that governs the Cnu-H-NS interaction is an ionic bond, unlike the hydrophobic interaction that is the major attractive force in most proteins.
Cnu 是一种由 71 个氨基酸组成的小蛋白，与 H-NS 复合物结合并结合到大肠杆菌染色体复制起点的特定序列上。为了了解 Cnu 和 H-NS 之间相互作用的机制，我们使用细菌遗传学来选择和分析不能与 H-NS 复合的 Cnu 变体。在 2000 个菌落中，鉴定出 40 种 Cnu 变体。大多数变体（82.5%）只有一个突变，但少数变体（17.5%）有两个氨基酸变化。体外测定用于鉴定真正不能与 H-NS 结合的 Cnu 变体。这些缺陷变体的变化仅发生在蛋白质表面的带电荷氨基酸（天冬氨酸、谷氨酸或赖氨酸）上。我们提出，控制 Cnu-H-NS 相互作用的吸引力是离子键，而不是大多数蛋白质中的主要吸引力的疏水相互作用。
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