Physicochemical properties and distinct DNA binding capacity of the repressor of temperate Staphylococcus aureus phage φ11
Physicochemical properties and distinct DNA binding capacity of the repressor of temperate Staphylococcus aureus phage φ11
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DOI：
10.1111/j.1742-4658.2009.06924.x
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发表时间：
2009-04-01
期刊：
影响因子：
5.4
通讯作者：
Sau, Subrata
中科院分区：
文献类型：
--
作者：
Ganguly, Tridib;Das, Malabika;Sau, Subrata
任何温和的金黄色葡萄球菌噬菌体的阻遏蛋白和同源操纵基因DNA尚未深入研究，尽管有可能丰富的葡萄球菌系统的分子生物学。在本研究中，使用极纯的阻遏物的温和金黄色葡萄球菌噬菌体phi 11（CI），我们证明，CI是由α-螺旋和β-折叠在很大程度上在室温下，具有两个域，在39摄氏度以上的温度下展开，并结合到两个网站在phi 11 cI-cro基因间区域的可变亲和力。上述Cl结合位点具有两个同源的15 bp反向重复序列（O 1和O2），其间隔18 bp。位于O 1和O2中及其周围的几个鸟嘌呤碱基与CI相互作用，表明这些15 bp的位点被用作阻遏物结合的操作者。CI与O 1和O2以协同的方式相互作用，并被发现作为同源二聚体与操纵基因DNA结合。有趣的是，CI没有显示出与另一个同源15 bp位点（O3）的明显结合，该位点与O 1和O2位于相同的初级免疫区。综上所述，这些结果表明，phi 11 CI和phi 11 CI-操作符复合体在结构水平上与拟似双链体非常相似。然而，phi 11 CI的作用模式可能与λ和相关的λ的阻遏蛋白不同。
The repressor protein and cognate operator DNA of any temperate Staphylococcus aureus phage have not been investigated in depth, despite having the potential to enrich the molecular biology of the staphylococcal system. In the present study, using the extremely pure repressor of temperate Staphylococcus aureus phage phi 11 (CI), we demonstrate that CI is composed of alpha-helix and beta-sheet to a substantial extent at room temperature, possesses two domains, unfolds at temperatures above 39 degrees C and binds to two sites in the phi 11 cI-cro intergenic region with variable affinity. The above CI binding sites harbor two homologous 15 bp inverted repeats (O1 and O2), which are spaced 18 bp apart. Several guanine bases located in and around O1 and O2 demonstrate interaction with CI, indicating that these 15 bp sites are used as operators for repressor binding. CI interacted with O1 and O2 in a cooperative manner and was found to bind to operator DNA as a homodimer. Interestingly, CI did not show appreciable binding to another homologous 15 bp site (O3) that was located in the same primary immunity region as O1 and O2. Taken together, these results suggest that phi 11 CI and the phi 11 CI-operator complex resemble significantly those of the lambdoid phages at the structural level. The mode of action of phi 11 CI, however, may be distinct from that of the repressor proteins of lambda and related phages.