Mechanism and substrate specificity of telomeric protein POT1 stimulation of the Werner syndrome helicase.
Mechanism and substrate specificity of telomeric protein POT1 stimulation of the Werner syndrome helicase.
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DOI：
10.1093/nar/gkn385
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发表时间：
2008-08
影响因子：
14.9
通讯作者：
Opresko PL
中科院分区：
文献类型：
--
作者：
Sowd G;Lei M;Opresko PL
RecQ解旋酶WRN蛋白的缺失导致癌症易感性早衰症Werner综合征（WS）。WS细胞表现出DNA复制和端粒保存缺陷。端粒单链结合蛋白POT 1刺激WRN解旋酶解开较长的端粒双链体，否则解旋不良。我们推断刺激可能通过POT 1在解旋期间在端粒底物上募集和保留WRN和/或通过POT 1加载在部分解旋的ssDNA链上以防止链再退火而发生。为了测试这些可能性，我们使用了在单链尾部、双链体或两者中具有POT 1结合序列的底物。POT 1与ssDNA尾部的结合并不改变WRN在非端粒双链体上的活性，也不将WRN募集到端粒ssDNA上。然而，POT 1结合的尾部抑制了具有单个3′-ssDNA尾部的端粒双链体上的WRN活性，该端粒双链体在开放构象中模拟端粒末端。与此相反，POT 1结合的尾巴刺激WRN解旋的分叉端粒双链体。这表明POT 1与ssDNA/dsDNA连接的相互作用调节WRN活性。此外，POT 1并没有提高保留端粒叉在解旋过程中的WRN。总的来说，这些数据表明，POT 1促进WRN解旋酶的表观持续合成能力，通过保持部分解旋链处于熔融状态，而不是防止WRN从底物解离。
Loss of the RecQ helicase WRN protein causes the cancer-prone progeroid disorder Werner syndrome (WS). WS cells exhibit defects in DNA replication and telomere preservation. The telomeric single-stranded binding protein POT1 stimulates WRN helicase to unwind longer telomeric duplexes that are otherwise poorly unwound. We reasoned that stimulation might occur by POT1 recruiting and retaining WRN on telomeric substrates during unwinding and/or by POT1 loading on partially unwound ssDNA strands to prevent strand re-annealing. To test these possibilities, we used substrates with POT1-binding sequences in the single-stranded tail, duplex or both. POT1 binding to ssDNA tails did not alter WRN activity on nontelomeric duplexes or recruit WRN to telomeric ssDNA. However, POT1 bound tails inhibited WRN activity on telomeric duplexes with a single 3′-ssDNA tail, which mimic telomeric ends in the open conformation. In contrast, POT1 bound tails stimulated WRN unwinding of forked telomeric duplexes. This indicates that POT1 interaction with the ssDNA/dsDNA junction regulates WRN activity. Furthermore, POT1 did not enhance retention of WRN on telomeric forks during unwinding. Collectively, these data suggest POT1 promotes the apparent processivity of WRN helicase by maintaining partially unwound strands in a melted state, rather than preventing WRN dissociation from the substrate.
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影响因子：
8
作者：
Machwe, A;Xiao, LR;Orren, DK
通讯作者：
Orren, DK
影响因子：
4.8
作者：
Doherty, KM;Sommers, JA;Brosh, RM
通讯作者：
Brosh, RM
DOI：
10.1073/pnas.0609410104
发表时间：
2007-02-13
影响因子：
11.1
作者：
Crabbe, Laure;Jauch, Anna;Karlseder, Jan
通讯作者：
Karlseder, Jan
影响因子：
3.3
作者：
Kibe, Tatsuya;Ono, Yuuki;Ueno, Masaru
通讯作者：
Ueno, Masaru
影响因子：
14.9
作者：
Huang, SR;Beresten, S;Campisi, J
通讯作者：
Campisi, J