Durand Dominique, Li de la Sierra-Gallay Ines, Brooks Mark A, Thompson Andrew W, Lazar Noureddine, Lisboa Johnny, van Tilbeurgh Herman, Quevillon-Cheruel Sophie
Institut de Biochimie et de Biophysique Moléculaire et Cellulaire, Université de Paris-Sud, UMR8619 du CNRS, Bâtiment 430, 91405 Orsay, France.
Acta Crystallogr Sect F Struct Biol Cryst Commun. 2012 Jun 1;68(Pt 6):638-43. doi: 10.1107/S1744309112011062. Epub 2012 May 22.
The Escherichia coli chromosome is organized into four macrodomains which are found in the replication-origin region (Ori), at the terminus (Ter) and on both its sides (Right and Left). The localization of the macrodomains is subject to programmed changes during the cell cycle. The compaction of the 800 kb Ter macrodomain relies on the binding of the MatP protein to a 13 bp matS motif repeated 23 times. MatP is a small DNA-binding protein of about 18 kDa that shares homology in its C-terminal region with the ribbon-helix-helix (RHH) motifs present in regulatory DNA-binding proteins such as CopG. In order to understand the DNA-compaction mechanism of MatP at an atomic level, it was decided to study the structure of apo MatP and of the nucleoprotein complex MatP-matS by both X-ray diffraction and SAXS analysis. It was demonstrated that MatP forms dimers that bind a single matS motif. Complete native X-ray data sets were collected and phasing of the diffraction data is under way.
大肠杆菌染色体被组织成四个宏观结构域，它们位于复制起始区域（Ori）、末端（Ter）及其两侧（右侧和左侧）。这些宏观结构域的定位在细胞周期中会发生程序性变化。800 kb的Ter宏观结构域的压缩依赖于MatP蛋白与重复23次的13 bp matS基序的结合。MatP是一种约18 kDa的小DNA结合蛋白，其C端区域与调控DNA结合蛋白（如CopG）中存在的带状螺旋螺旋（RHH）基序具有同源性。为了在原子水平上理解MatP的DNA压缩机制，决定通过X射线衍射和小角X射线散射（SAXS）分析来研究无配体MatP和核蛋白复合物MatP-matS的结构。结果表明，MatP形成二聚体并结合单个matS基序。已收集完整的天然X射线数据集，衍射数据的相位分析正在进行中。
