Coupling DNA-binding and ATP hydrolysis in Escherichia coli RecQ: role of a highly conserved aromatic-rich sequence.
Coupling DNA-binding and ATP hydrolysis in Escherichia coli RecQ: role of a highly conserved aromatic-rich sequence.
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DOI：
10.1093/nar/gki999
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发表时间：
2005
影响因子：
14.9
通讯作者：
Keck JL
中科院分区：
文献类型：
--
作者：
Zittel MC;Keck JL
RecQ酶是广泛保守的超家族-2（SF-2）DNA解旋酶，其在DNA代谢中起关键作用。RecQ蛋白利用ATP水解的能量来驱动DNA解旋;然而，RecQ将ATP酶活性与DNA结合/解旋联系起来的机制尚不清楚。在许多超家族-1（SF-1）DNA解旋酶中，解旋酶序列基序III通过结合单链（ss）DNA和ATP来连接这些活性。然而，这些酶中存在的基序III中富含ssDNA结合芳香族的元素在SF-2解旋酶中缺失，这就提出了这些酶如何将ATP水解与DNA结合/解旋联系起来的问题。我们发现，大肠杆菌RecQ包含一个保守的芳香族丰富的环在其解旋酶结构域之间的基序II和III。虽然RecQ富含芳香环的位置相对于SF-1酶在拓扑学上不同，但两个环都映射到相似的三级结构位置。我们使用片段内具有单个氨基酸取代的RecQ变体检查了大肠杆菌RecQ富含芳香环的功能。我们的研究结果表明，芳香族丰富的环RecQ耦合ATP酶和DNA结合/解旋活动是至关重要的。我们的研究还表明，RecQ的富含芳香环可能会耦合ATP水解DNA结合的机制不同的方式从SF-1解旋酶。
RecQ enzymes are broadly conserved Superfamily-2 (SF-2) DNA helicases that play critical roles in DNA metabolism. RecQ proteins use the energy of ATP hydrolysis to drive DNA unwinding; however, the mechanisms by which RecQ links ATPase activity to DNA-binding/unwinding are unknown. In many Superfamily-1 (SF-1) DNA helicases, helicase sequence motif III links these activities by binding both single-stranded (ss) DNA and ATP. However, the ssDNA-binding aromatic-rich element in motif III present in these enzymes is missing from SF-2 helicases, raising the question of how these enzymes link ATP hydrolysis to DNA-binding/unwinding. We show that Escherichia coli RecQ contains a conserved aromatic-rich loop in its helicase domain between motifs II and III. Although placement of the RecQ aromatic-rich loop is topologically distinct relative to the SF-1 enzymes, both loops map to similar tertiary structural positions. We examined the functions of the E.coli RecQ aromatic-rich loop using RecQ variants with single amino acid substitutions within the segment. Our results indicate that the aromatic-rich loop in RecQ is critical for coupling ATPase and DNA-binding/unwinding activities. Our studies also suggest that RecQ's aromatic-rich loop might couple ATP hydrolysis to DNA-binding in a mechanistically distinct manner from SF-1 helicases.
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影响因子：
14.9
作者：
Bernstein, DA;Keck, JL
通讯作者：
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影响因子：
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