Wang Y C, Burkhart W A, Mackey Z B, Moyer M B, Ramos W, Husain I, Chen J, Besterman J M, Tomkinson A E
Institute of Biotechnology, Center for Molecular Medicine, University of Texas Health Science Center San Antonio 78245.
J Biol Chem. 1994 Dec 16;269(50):31923-8.
Mammalian cells contain three biochemically distinct DNA ligases. In this report we describe the purification of DNA ligase II to homogeneity from bovine liver nuclei. This enzyme interacts with ATP to form an enzyme-AMP complex, in which the AMP moiety is covalently linked to a lysine residue. An adenylylated peptide from DNA ligase II contains the sequence, Lys-Tyr-Asp-Gly-Glu-Arg, which is homologous to the active site motif conserved in ATP-dependent DNA ligases. The sequences adjacent to this motif in DNA ligase II are different from the comparable sequences in DNA ligase I, demonstrating that these enzymes are encoded by separate genes. The amino acid sequences of 15 DNA ligase II peptides exhibit striking homology (65% overall identity) with vaccinia DNA ligase. These peptides are also homologous (31% overall identity) with the catalytic domain of mammalian DNA ligase I, indicating that the genes encoding DNA ligases I and II probably evolved from a common ancestral gene. Since vaccinia DNA ligase is not required for DNA replication but influences the ability of the virus to survive DNA damage, the homology between this enzyme and DNA ligase II suggests that DNA ligase II may be involved in DNA repair.
哺乳动物细胞含有三种生物化学性质不同的DNA连接酶。在本报告中，我们描述了从牛肝细胞核中纯化出均一的DNA连接酶II。这种酶与ATP相互作用形成酶-AMP复合物，其中AMP部分共价连接到一个赖氨酸残基上。来自DNA连接酶II的一个腺苷酸化肽含有序列Lys-Tyr-Asp-Gly-Glu-Arg，该序列与ATP依赖性DNA连接酶中保守的活性位点基序同源。DNA连接酶II中该基序相邻的序列与DNA连接酶I中的可比序列不同，这表明这些酶由不同的基因编码。15个DNA连接酶II肽的氨基酸序列与痘苗病毒DNA连接酶具有显著的同源性（总体同一性为65%）。这些肽也与哺乳动物DNA连接酶I的催化结构域同源（总体同一性为31%），这表明编码DNA连接酶I和II的基因可能起源于一个共同的祖先基因。由于痘苗病毒DNA连接酶不是DNA复制所必需的，但会影响病毒在DNA损伤中存活的能力，这种酶与DNA连接酶II之间的同源性表明DNA连接酶II可能参与DNA修复。
