On the effect of covalently appended quinolones on termini of DNA duplexes.
On the effect of covalently appended quinolones on termini of DNA duplexes.
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关于共价附加喹诺酮类药物对 DNA 双链体末端的影响。
DOI：
10.1021/ja0125117
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发表时间：
2002
影响因子：
15
通讯作者：
Richert,Clemens
中科院分区：
文献类型：
--
作者：
Tuma,Jennifer;Connors,WilliamH;Stitelman,DavidH;Richert,Clemens
喹诺酮类药物是临床上广泛使用的促旋酶抑制剂。当作为5 '-酰氨基取代基共价连接到寡核苷酸上时，发现喹诺酮可以稳定寡核苷酸的双链体，防止热变性。对于短双链体，例如qu-T*GCGCA，其中qu是喹诺酮残基，T* 是5 '-氨基-5'-脱氧胸苷残基，测量到UV熔点增加高达27.8 °C。证明了对所有测试的喹诺酮类药物的稳定作用，即萘啶酸、恶喹酸、哌哌甲酯酸、西诺沙星、诺氟沙星和氧氟沙星。通过二维NMR光谱和受限分子动力学求解了（oa-T*GCGCA）2的三维结构，其中oa是oxolinic酸残基。在该复合物中，oxolinic酸残基破坏末端T1：A6碱基对并堆叠在G2：C5碱基对上。被置换的腺苷残基结合在核心双链体的小沟中，而胸苷残基则与恶喹酸残基结合。由此形成的“分子帽”紧密地贴合在G：C碱基对上，导致碱基配对保真度增加，如用序列oa-T*GGTTGAC和含有错配核碱基的靶链进行的UV熔解实验中所证明的。“分子帽”的结构及其破坏的末端碱基对也可能有助于模拟喹诺酮类药物如何阻断促旋酶活性位点中DNA链的重新连接。
Quinolones are gyrase inhibitors that are widely used as antibiotics in the clinic. When covalently attached to oligonucleotides as 5‘-acylamido substituents, quinolones were found to stabilize duplexes of oligonucleotides against thermal denaturation. For short duplexes, such as qu-T*GCGCA, where qu is a quinolone residue and T* is a 5‘-amino-5‘-deoxythymidine residue, an increase in the UV melting point of up to 27.8 °C was measured. The stabilizing effect was demonstrated for all quinolones tested, namely nalidixic acid, oxolinic acid, pipemidic acid, cinoxacin, norfloxacin, and ofloxacin. The three-dimensional structure of (oa-T*GCGCA)2, where oa is an oxolinic acid residue, was solved by two-dimensional NMR spectroscopy and restrained molecular dynamics. In this complex, the oxolinic acid residues disrupt the terminal T1:A6 base pairs and stack on the G2:C5 base pairs. The displaced adenosine residues bind in the minor groove of the core duplex, while the thymidine residues pack against the oxolinic acid residues. The “molecular cap” thus formed fits tightly on the G:C base pairs, resulting in increased base-pairing fidelity, as demonstrated in UV melting experiments with the sequence oa-T*GGTTGAC and target strands containing a mismatched nucleobase. The structure of the “molecular cap” with its disrupted terminal base pair may also be helpful for modeling how quinolones block re-ligation of DNA strands in the active site of gyrases.