Department of Chemistry, University of Copenhagen, Denmark.
CNRS, CEA, IBS, Université Grenoble Alpes, Grenoble, France.
FEBS Lett. 2018 May;592(10):1738-1750. doi: 10.1002/1873-3468.13060. Epub 2018 May 13.
Temperate bacteriophages are known for their bistability, which in TP901-1 is controlled by two proteins, CI and MOR. Clear 1 repressor (CI) is hexameric and binds three palindromic operator sites via an N-terminal helix-turn-helix domain (NTD). A dimeric form, such as the truncated CI∆58 investigated here, is necessary for high-affinity binding to DNA. The crystal structure of the dimerization region (CTD ) is determined here, showing that it forms a pair of helical hooks. This newly determined structure is used together with the known crystal structure of the CI-NTD and small angle X-ray scattering data, to determine the solution structure of CI∆58 in complex with a palindromic operator site, showing that the two NTDs bind on opposing sides of the DNA helix.
温和噬菌体以其双稳态性而闻名，TP901-1 中的双稳态性由两个蛋白质 CI 和 MOR 控制。清晰 1 阻遏物（CI）是六聚体，通过 N 端螺旋-转角-螺旋结构域（NTD）结合三个回文操纵子位点。二聚体形式，如这里研究的截断 CI∆58，对于高亲和力结合 DNA 是必需的。这里确定了二聚化区（CTD）的晶体结构，显示它形成一对螺旋钩。将新确定的结构与已知的 CI-NTD 晶体结构和小角度 X 射线散射数据一起使用，确定了与回文操纵子位点结合的 CI∆58 的溶液结构，表明两个 NTD 结合在 DNA 螺旋的相对侧。
