Hwang Y, Rowley D, Rhodes D, Gertsch J, Fenical W, Bushman F
Infectious Disease Laboratory, The Salk Institute, La Jolla, California, USA.
Mol Pharmacol. 1999 Jun;55(6):1049-53. doi: 10.1124/mol.55.6.1049.
At present no antiviral agents are available for treatment of infection by the pathogenic poxvirus molluscum contagiosum virus (MCV). Here we report the identification and characterization of an inhibitor active against the virus-encoded type-1 topoisomerase, an enzyme likely to be required for MCV replication. We screened a library of marine extracts and natural products from microorganisms using MCV topoisomerase assays in vitro. The cyclic depsipeptide sansalvamide A was found to inhibit topoisomerase-catalyzed DNA relaxation. Sansalvamide A was inactive against two other DNA-modifying enzymes tested as a counterscreen. Assays of discrete steps in the topoisomerase reaction cycle revealed that sansalvamide A inhibited DNA binding and thereby covalent complex formation, but not resealing of a DNA nick in a preformed covalent complex. Sansalvamide A also inhibits DNA binding by the isolated catalytic domain, thereby specifying the part of the protein sensitive to sansalvamide A. These data specify the mechanism by which sansalvamide A inhibits MCV topoisomerase. Cyclic depsipeptides related to sansalvamide A represent a potentially promising chemical family for development of anti-MCV agents.
目前尚无抗病毒药物可用于治疗由致病性痘病毒传染性软疣病毒（MCV）引起的感染。在此，我们报告了一种对病毒编码的1型拓扑异构酶具有活性的抑制剂的鉴定和特性，该酶可能是MCV复制所必需的。我们使用体外MCV拓扑异构酶测定法筛选了来自微生物的海洋提取物和天然产物文库。发现环缩肽sansalvamide A可抑制拓扑异构酶催化的DNA松弛。作为对照筛选，sansalvamide A对另外两种测试的DNA修饰酶无活性。对拓扑异构酶反应循环中各个步骤的测定表明，sansalvamide A抑制DNA结合，从而抑制共价复合物的形成，但不抑制预先形成的共价复合物中DNA切口的重新封闭。Sansalvamide A还抑制分离的催化结构域的DNA结合，从而确定了蛋白质中对sansalvamide A敏感的部分。这些数据明确了sansalvamide A抑制MCV拓扑异构酶的机制。与sansalvamide A相关的环缩肽代表了开发抗MCV药物的一个潜在有前景的化学家族。
