Blanco L, Bernad A, Blasco M A, Salas M
Centro de Biología Molecular (CSIC-UAM), Universidad Autónoma, Madrid, Spain.
Gene. 1991 Apr;100:27-38. doi: 10.1016/0378-1119(91)90346-d.
In addition to the general 3'-5' exonuclease domain described by Bernad et al. [Cell 59 (1989) 219-228] significant amino acid (aa) sequence similarity has been found in the C-terminal portion of 27 DNA-dependent DNA polymerases belonging to the two main superfamilies: (i) Escherichia coli DNA polymerase I (PolI)-like prokaryotic DNA polymerases, and (ii) DNA polymerase alpha-like prokaryotic and eukaryotic (viral and cellular) DNA polymerases. The six most conserved C-terminal regions, spanning approx. 340 aa, are located in the same linear arrangement and contain highly conserved motifs and critical residues involved in the polymerization function. According to the three-dimensional model of PolIk (Klenow fragment), these six conserved regions are located in the proposed polymerization domain, forming the metal and dNTP binding sites and the cleft for holding the DNA template. Site-directed mutagenesis in the phi 29 DNA polymerase supports some of these structural predictions. Therefore, it is likely that a 'Klenow-like core', containing the DNA polymerase and 3'-5' exonuclease activities, has evolved from a common ancestor, giving rise to the present-day prokaryotic and eukaryotic DNA polymerases.
除了Bernad等人[《细胞》59 (1989) 219 - 228]所描述的通用3'-5'核酸外切酶结构域外，在属于两个主要超家族的27种依赖DNA的DNA聚合酶的C末端部分发现了显著的氨基酸(aa)序列相似性：(i)大肠杆菌DNA聚合酶I (PolI)样原核DNA聚合酶，以及(ii) DNA聚合酶α样原核和真核(病毒和细胞) DNA聚合酶。六个最保守的C末端区域，跨越约340个氨基酸，以相同的线性排列定位，并包含参与聚合功能的高度保守基序和关键残基。根据PolIk (克列诺夫片段)的三维模型，这六个保守区域位于提议的聚合结构域中，形成金属和dNTP结合位点以及用于容纳DNA模板的裂隙。φ29 DNA聚合酶中的定点诱变支持了其中一些结构预测。因此，很可能一个包含DNA聚合酶和3'-5'核酸外切酶活性的“克列诺夫样核心”从一个共同祖先进化而来，产生了当今的原核和真核DNA聚合酶。
