Plasmodium falciparum SSB Tetramer Binds Single-Stranded DNA Only in a Fully Wrapped Mode
Plasmodium falciparum SSB Tetramer Binds Single-Stranded DNA Only in a Fully Wrapped Mode
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DOI：
10.1016/j.jmb.2012.04.022
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发表时间：
2012-07-20
影响因子：
5.6
通讯作者：
Lohman, Timothy M.
中科院分区：
文献类型：
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作者：
Antony, Edwin;Kozlov, Alexander G.;Lohman, Timothy M.
四聚体大肠杆菌单链DNA （ssDNA）结合蛋白（Ec-SSB）通过与ssDNA结合并直接与多种DNA修复和复制蛋白相互作用，在DNA代谢中起作用。Ec-SSB四聚体可以以多种DNA结合模式结合ssDNA，这些模式在ssDNA包裹程度上有所不同。在这里，我们发现来自疟原虫恶性疟原虫（Pf-SSB）的结构类似的SSB蛋白也与ssDNA紧密结合，但不像Ec-SSB那样显示出相同数量的ssDNA结合模式，仅以位点大小为52- 65nt /四聚体的完全包裹的复合物与ssDNA结合。Pf-SSB不会转变为Ec-SSB所观察到的更合作（SSB）（35）的DNA结合模式。与此一致的是，Pf-SSB四聚体也没有表现出在Ec-SSB中明显的与第二分子（dT）（35）结合的四聚体内负协同性。这些发现强调了这两种高度保守的同四聚体SSB蛋白在DNA结合特性上的差异，这些差异可能是为了适应它们在细胞中的特定功能而量身定制的。(C) 2012 Elsevier Ltd.版权所有。
The tetrameric Escherichia coli single-stranded DNA (ssDNA) binding protein (Ec-SSB) functions in DNA metabolism by binding to ssDNA and interacting directly with numerous DNA repair and replication proteins. Ec-SSB tetramers can bind ssDNA in multiple DNA binding modes that differ in the extent of ssDNA wrapping. Here, we show that the structurally similar SSB protein from the malarial parasite Plasmodium falciparum (Pf-SSB) also binds tightly to ssDNA but does not display the same number of ssDNA binding modes as Ec-SSB, binding ssDNA exclusively in fully wrapped complexes with site sizes of 52-65 nt/tetramer. Pf-SSB does not transition to the more cooperative (SSB)(35) DNA binding mode observed for Ec-SSB. Consistent with this, Pf-SSB tetramers also do not display the dramatic intra-tetramer negative cooperativity for binding of a second (dT)(35) molecule that is evident in Ec-SSB. These findings highlight variations in the DNA binding properties of these two highly conserved homotetrameric SSB proteins, and these differences might be tailored to suit their specific functions in the cell. (C) 2012 Elsevier Ltd. All rights reserved.