Allosteric regulation of the primase (DnaG) activity by the clamp-loader (τ) in vitro
Allosteric regulation of the primase (DnaG) activity by the clamp-loader (τ) in vitro
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DOI：
10.1111/j.1365-2958.2009.06668.x
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发表时间：
2009-04-01
影响因子：
3.6
通讯作者：
Soultanas, Panos
中科院分区：
文献类型：
--
作者：
Chintakayala, Kiran;Machon, Cristina;Soultanas, Panos
在DNA复制过程中，解旋酶（DnaB）在复制体中招募引发酶（DnaG）以启动新DNA链的聚合。DnaB连接到夹加载器的tau亚基上，夹加载器加载β夹并使前导链和滞后链上的核心聚合酶相互连接。tau-DnaB-DnaG三元复合物是复制体的核心，其功能可能受到变构相互作用的复杂网络的调节。使用一个稳定的三元复合物，包括引发酶和解旋酶从嗜热脂肪土芽孢杆菌和从枯草芽孢杆菌的夹装载机的tau亚基，我们表明，在DnaB-tau相互作用的变化可以刺激变构引物合成DnaG在体外。A550 V tau突变体比天然蛋白更有效地刺激引发酶活性。截短tau蛋白的最后18个C-末端残基在体外显示出在天然tau蛋白中被抑制的DnaG刺激作用。因此，tau-DnaB相互作用的变化变构地影响引物合成。尽管tau的这些C-末端残基不直接参与与DnaB的相互作用，但它们可以作为通过tau-DnaB-DnaG途径调节复制体的tau相互作用组分的引物合成的功能性网关。
During DNA replication the helicase (DnaB) recruits the primase (DnaG) in the replisome to initiate the polymerization of new DNA strands. DnaB is attached to the tau subunit of the clamp-loader that loads the beta clamp and interconnects the core polymerases on the leading and lagging strands. The tau-DnaB-DnaG ternary complex is at the heart of the replisome and its function is likely to be modulated by a complex network of allosteric interactions. Using a stable ternary complex comprising the primase and helicase from Geobacillus stearothermophilus and the tau subunit of the clamp-loader from Bacillus subtilis we show that changes in the DnaB-tau interaction can stimulate allosterically primer synthesis by DnaG in vitro. The A550V tau mutant stimulates the primase activity more efficiently than the native protein. Truncation of the last 18 C-terminal residues of tau elicits a DnaG-stimulatory effect in vitro that appears to be suppressed in the native tau protein. Thus changes in the tau-DnaB interaction allosterically affect primer synthesis. Although these C-terminal residues of tau are not involved directly in the interaction with DnaB, they may act as a functional gateway for regulation of primer synthesis by tau-interacting components of the replisome through the tau-DnaB-DnaG pathway.