RIKEN SPring-8 Center, Harima Institute, 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan.
RIKEN SPring-8 Center, Harima Institute, 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan.
J Biol Chem. 2012 Mar 23;287(13):10394-10402. doi: 10.1074/jbc.M112.343210. Epub 2012 Feb 10.
All thermophilic and hyperthermophilic archaea encode homologs of dimeric Alba (Sac10b) proteins that bind cooperatively at high density to DNA. Here, we report the 2.0 Å resolution crystal structure of an Alba2 (Ape10b2)-dsDNA complex from Aeropyrum pernix K1. A rectangular tube-like structure encompassing duplex DNA reveals the positively charged residues in the monomer-monomer interface of each dimer packing on either side of the bound dsDNA in successive minor grooves. The extended hairpin loop connecting strands β3 and β4 undergoes significant conformational changes upon DNA binding to accommodate the other Alba2 dimer during oligomerization. Mutational analysis of key interacting residues confirmed the specificity of Alba2-dsDNA interactions.
所有嗜热菌和超嗜热古菌都编码二聚体 Alba（Sac10b）蛋白的同源物，该蛋白以高浓度协同结合 DNA。在这里，我们报告了来自 Aeropyrum pernix K1 的 Alba2（Ape10b2）-dsDNA 复合物的 2.0 Å 分辨率晶体结构。一个矩形管状结构包围着双链 DNA，揭示了每个二聚体单体-单体界面中的正电荷残基在结合的 dsDNA 的每一侧沿连续的小沟排列。连接β3 和β4 链的延伸发夹环在 DNA 结合时发生显著构象变化，以在寡聚化过程中容纳另一个 Alba2 二聚体。关键相互作用残基的突变分析证实了 Alba2-dsDNA 相互作用的特异性。
