Leavitt M C, Ito J
Department of Microbiology and Immunology, University of Arizona Health Sciences Center, Tucson 85724.
Proc Natl Acad Sci U S A. 1989 Jun;86(12):4465-9. doi: 10.1073/pnas.86.12.4465.
T5 DNA polymerase, a highly processive single-polypeptide enzyme, has been analyzed for its primary structural features. The amino acid sequence of T5 DNA polymerase has a high degree of homology with that of DNA polymerase I from Escherichia coli and retains many of the amino acid residues that have been implicated in the 3'----5' exonuclease and DNA polymerase activities of that enzyme. Alignment with sequences of polymerase I and T7 DNA polymerase was used to identify regions possibly involved in the high processivity of this enzyme. Further, amino acid sequence comparisons of T5 DNA polymerase with a large group of DNA polymerases previously shown to exhibit little similarity to polymerase I indicate certain sequence segments are shared among distantly related DNA polymerases. These shared regions have been implicated in the 3'----5' exonuclease function of polymerase I, which suggests that the proofreading domains of all these enzymes may be evolutionarily related.
T5 DNA聚合酶是一种具有高度持续性的单多肽酶，已对其一级结构特征进行了分析。T5 DNA聚合酶的氨基酸序列与大肠杆菌DNA聚合酶I的氨基酸序列具有高度同源性，并保留了许多与该酶的3'→5'核酸外切酶和DNA聚合酶活性相关的氨基酸残基。与聚合酶I和T7 DNA聚合酶的序列比对用于鉴定可能与该酶的高持续性有关的区域。此外，T5 DNA聚合酶与先前显示与聚合酶I几乎没有相似性的一大类DNA聚合酶的氨基酸序列比较表明，某些序列片段在远缘相关的DNA聚合酶之间是共享的。这些共享区域与聚合酶I的3'→5'核酸外切酶功能有关，这表明所有这些酶的校对结构域可能在进化上相关。
