Interplay of Mre11 nuclease with Dna2 plus Sgs1 in Rad51-dependent recombinational repair.
Interplay of Mre11 nuclease with Dna2 plus Sgs1 in Rad51-dependent recombinational repair.
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DOI：
10.1371/journal.pone.0004267
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发表时间：
2009
期刊：
影响因子：
3.7
通讯作者：
Campbell JL
中科院分区：
文献类型：
--
作者：
Budd ME;Campbell JL
Mre11/Rad50/Xrs2复合体通过与双链断裂末端结合来启动IR修复，导致5‘到3’外切酶降解，产生单链3‘悬垂，能够侵入未断裂的染色体。所涉及的核酸酶(S)还不是很清楚。Mre11编码一个核酸酶，但它的活性是3‘到5’，而不是5‘到3’。此外，仅失活Mre11核酸酶活性而不激活其其他修复功能的突变Mre11-D56N和Mre11-H125N对IR具有抵抗力。这表明另一种核酸酶可以催化5‘到3’的降解。到目前为止还没有测试过的一个候选核酸酶是DNA2解旋酶/核酸酶，因为它是由一个必要的基因编码的。我们最近报道了用pif1Δ抑制DNA 2Δ的致死性的能力。DNA2Δpif1Δ突变体具有抗IR特性。我们已经确定，DNA2Δpif1Δmre11-D56N和dna 2Δpif1Δmre11-H125N株与mre11Δ株一样对IR敏感，这表明在没有dna 2的情况下，mre11核酸酶进行修复。DNA2Δpif1Δmre11-D56N三重突变体被表达mre11、dna 2或具有解旋酶和功能核酸酶缺陷的突变体dna 2K1080E的质粒所补充，表明dna 2的核酸酶在IR修复中补偿了mre11核酸酶的缺失，可能是在Dsb末端5‘到3’降解。我们进一步证明SGS1Δmre11-H125N，而不是SGS1Δ对IR非常敏感，这意味着SGS1解旋酶参与了DNA 2介导的途径。
The Mre11/Rad50/Xrs2 complex initiates IR repair by binding to the end of a double-strand break, resulting in 5′ to 3′ exonuclease degradation creating a single-stranded 3′ overhang competent for strand invasion into the unbroken chromosome. The nuclease(s) involved are not well understood. Mre11 encodes a nuclease, but it has 3′ to 5′, rather than 5′ to 3′ activity. Furthermore, mutations that inactivate only the nuclease activity of Mre11 but not its other repair functions, mre11-D56N and mre11-H125N, are resistant to IR. This suggests that another nuclease can catalyze 5′ to 3′ degradation. One candidate nuclease that has not been tested to date because it is encoded by an essential gene is the Dna2 helicase/nuclease. We recently reported the ability to suppress the lethality of a dna2Δ with a pif1Δ. The dna2Δ pif1Δ mutant is IR-resistant. We have determined that dna2Δ pif1Δ mre11-D56N and dna2Δ pif1Δ mre11-H125N strains are equally as sensitive to IR as mre11Δ strains, suggesting that in the absence of Dna2, Mre11 nuclease carries out repair. The dna2Δ pif1Δ mre11-D56N triple mutant is complemented by plasmids expressing Mre11, Dna2 or dna2K1080E, a mutant with defective helicase and functional nuclease, demonstrating that the nuclease of Dna2 compensates for the absence of Mre11 nuclease in IR repair, presumably in 5′ to 3′ degradation at DSB ends. We further show that sgs1Δ mre11-H125N, but not sgs1Δ, is very sensitive to IR, implicating the Sgs1 helicase in the Dna2-mediated pathway.
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影响因子：
16
作者：
Lengsfeld, Bettina M.;Rattray, Alison J.;Paull, Tanya T.
通讯作者：
Paull, Tanya T.
影响因子：
11.4
作者：
Gangloff, S;de Massy, B;Fabre, F
通讯作者：
Fabre, F
影响因子：
4.5
作者：
Budd ME;Tong AH;Polaczek P;Peng X;Boone C;Campbell JL
通讯作者：
Campbell JL
影响因子：
5.3
作者：
Budd, ME;Campbell, JL
通讯作者：
Campbell, JL
DOI：
10.1073/pnas.1431624100
发表时间：
2003-07-08
影响因子：
11.1
作者：
Imamura, O;Campbell, JL
通讯作者：
Campbell, JL