SPECIALIZED NUCLEOPROTEIN STRUCTURES AT THE ORIGIN OF REPLICATION OF BACTERIOPHAGE-LAMBDA - LOCALIZED UNWINDING OF DUPLEX DNA BY A 6-PROTEIN REACTION
SPECIALIZED NUCLEOPROTEIN STRUCTURES AT THE ORIGIN OF REPLICATION OF BACTERIOPHAGE-LAMBDA - LOCALIZED UNWINDING OF DUPLEX DNA BY A 6-PROTEIN REACTION
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DOI：
10.1073/pnas.83.20.7638
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发表时间：
1986-10-01
影响因子：
11.1
通讯作者：
MCMACKEN, R
中科院分区：
文献类型：
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作者：
DODSON, M;ECHOLS, H;MCMACKEN, R
噬菌体的O蛋白。将DNA复制的起始定位于DNA上的独特位点。genome，ori. tagoda..通过电子显微镜，我们推断，O的结合到ori. tagoda。启动一系列蛋白质添加和转移反应，最终导致起始DNA的局部解旋，产生用于启动DNA复制的预引发结构。我们可以将这种预启动反应分为三个阶段，前两个阶段我们已经描述过了。首先，二聚体O蛋白与多个DNA结合位点结合并自缔合形成核蛋白结构，即O-体。第二，. P和宿主DnaB蛋白与O-体相互作用以产生更大的复合物，该复合物包括来自邻近O结合位点的富含A + T的区域的额外DNA。第三，DnaJ，DnaK，和Ssb蛋白和ATP的加入导致来源特异性解旋反应，可能由DnaB的解旋酶活性催化。解旋反应是单向的，从原点“向右”进行。解旋的最小DNA序列由两个O结合位点和结合位点右侧相邻的富含A+ T的区域组成。我们的结论是，。O蛋白定位并启动六蛋白顺序反应，负责但先于DNA复制的精确启动。与O-小体相似的特殊核蛋白结构可能是DNA交易的一般特征，需要非常精确的定位和控制。
The O protein of bacteriophage .lambda. localizes the initiation of DNA replication to a unique site on the .lambda. genome, ori.lambda.. By means of electron microscopy, we infer that the binding of O to ori.lambda. initiates a series of protein addition and transfer reactions that culminate in localized unwinding of the origin DNA, generating a prepriming structure for the initiation of DNA replication. We can define three stages to this prepriming reaction, the first two of which we have characterized previously. First, dimeric O protein binds to multiple DNA binding sites and self-associates to form a nucleoprotein structure, the O-some. Second, .lambda. P and host DnaB proteins interact with the O-some to generate a larger complex that includes additional DNA from an A + T-rich region adjacent to the O binding sites. Third, the addition of the DnaJ, DnaK, and Ssb proteins and ATP results in an origin-specific unwinding reaction, probably catalyzed by the helicase activity of DnaB. The unwinding reaction is unidirectional, proceeding "right-ward" from the origin. The minimal DNA sequence competent for unwinding consists of two O binding sites and the adjacent A+T-rich regeion to the right of the binding sites. We conclude that the .lambda. O protein localizes and initiates a six-protein sequential reaction responsible for but preceding the precise initiation of DNA replication. Specialized nucleoprotein structures similar to the O-some may be a general feature of DNA transactions requiring extraordinary precision in localization and control.