Dissection of the DNA mimicry of the bacteriophage T7 Ocr protein using chemical modification.
Dissection of the DNA mimicry of the bacteriophage T7 Ocr protein using chemical modification.
复制标题
DOI：
10.1016/j.jmb.2009.06.020
复制
发表时间：
2009-08-21
影响因子：
5.6
通讯作者：
Dryden, David T. F.
中科院分区：
文献类型：
--
作者：
Stephanou, Augoustinos S.;Roberts, Gareth A.;Cooper, Laurie P.;Clarke, David J.;Thomson, Andrew R.;MacKay, C. Logan;Nutley, Margaret;Cooper, Alan;Dryden, David T. F.
噬菌体T7的同二聚体Ocr（克服经典限制性内切）蛋白是双链DNA的分子模拟物，是细菌I型限制性内切/修饰系统的高效竞争性抑制剂。Ocr的表面充满了酸性残基，类似于DNA的磷酸主链。此外，Ocr还模拟了弯曲的24bp DNA分子的整体尺寸。在这项研究中，我们试图通过化学修饰Ocr表面的负电荷来描述DNA模仿的这两种机制。我们的分析表明，去除每个Ocr单体约46%的羧酸基导致模型I型限制/修饰体系中甲基转移酶的结合亲和力降低~ 50倍。具有这种修饰程度的Ocr与甲基转移酶之间的亲和力降低与DNA对甲基转移酶的亲和力相当。去除约86%羧酸基团的额外修饰进一步降低了其结合亲和力，尽管修饰后的Ocr仍然通过可归因于弯曲DNA分子形状模仿的机制与甲基转移酶结合。我们的研究结果表明，Ocr的静电模拟将其与靶酶的结合亲和力提高了高达800倍。
The homodimeric Ocr (overcome classical restriction) protein of bacteriophage T7 is a molecular mimic of double-stranded DNA and a highly effective competitive inhibitor of the bacterial type I restriction/modification system. The surface of Ocr is replete with acidic residues that mimic the phosphate backbone of DNA. In addition, Ocr also mimics the overall dimensions of a bent 24-bp DNA molecule. In this study, we attempted to delineate these two mechanisms of DNA mimicry by chemically modifying the negative charges on the Ocr surface. Our analysis reveals that removal of about 46% of the carboxylate groups per Ocr monomer results in an ∼ 50-fold reduction in binding affinity for a methyltransferase from a model type I restriction/modification system. The reduced affinity between Ocr with this degree of modification and the methyltransferase is comparable with the affinity of DNA for the methyltransferase. Additional modification to remove ∼ 86% of the carboxylate groups further reduces its binding affinity, although the modified Ocr still binds to the methyltransferase via a mechanism attributable to the shape mimicry of a bent DNA molecule. Our results show that the electrostatic mimicry of Ocr increases the binding affinity for its target enzyme by up to ∼ 800-fold.
登录
查看更多内容
影响因子：
14.9
作者：
Atanasiu, C;Su, TJ;Dryden, DTF
通讯作者：
Dryden, DTF
影响因子：
2.9
作者：
Blackstock, JJ;Egelhaaf, SU;Poon, WCK
通讯作者：
Poon, WCK
影响因子：
3.4
作者：
Gallagher, K;Sharp, K
通讯作者：
Sharp, K
影响因子：
--
作者：
Carraway, K L;Koshland, D E Jr
通讯作者：
Koshland, D E Jr
影响因子：
3.8
作者：
Cooper, A
通讯作者：
Cooper, A