Characterization of nuclease-dependent functions of Exo1p in Saccharomyces cerevisiae
Characterization of nuclease-dependent functions of Exo1p in Saccharomyces cerevisiae
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DOI：
10.1016/s1568-7864(02)00114-3
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发表时间：
2002-11-03
期刊：
影响因子：
3.8
通讯作者：
Liskay, RM
中科院分区：
文献类型：
--
作者：
Tran, PT;Erdeniz, N;Liskay, RM
Exo1p是Rad2p家族结构特异性核酸酶的成员，包含保守的N和I核酸酶结构域。Exo1p参与了许多DNA代谢过程，如重组、双链断裂修复和DNA错配修复（MMR）。在本报告中，我们描述了全长野生型和突变型Exo1p的体外和体内特性。在这里，我们证明了全长酵母Exo1p具有固有的5‘-3’外切酶活性，正如之前报道的那样，但也具有皮瓣内切酶活性。我们的研究表明，在N和I核酸酶结构域，Exo1p与Rad2p家族的其他特征成员具有相似但不完全相同的结构-功能关系。我们检测的两个exo1p突变体显示双链DNA (dsDNA) 5‘-3’外切酶和flap-内切酶活性均存在缺陷。检测这两个exo1突变与rad27Delta的遗传相互作用表明，对于Rad27p的生存能力来说，Exo1p的flap- endoonucase活性而不是dsDNA的5‘-3’外切酶是冗余的。此外，我们的体内结果还表明，许多exo1Delta表型依赖于Exo1p的完全催化活性。最后，我们的发现和其他研究者的发现表明，Exolp在DNA MMR过程中具有催化和结构能力。(C) 2002 Elsevier Science B.V.版权所有
Exo1p is a member of the Rad2p family of structure-specific nucleases that contain conserved N and I nuclease domains. Exo1p has been implicated in numerous DNA metabolic processes, such as recombination, double-strand break repair and DNA mismatch repair (MMR). In this report, we describe in vitro and in vivo characterization of full-length wild-type and mutant forms of Exo1p. Herein, we demonstrate that full-length yeast Exo1p possesses an intrinsic 5'-3'exonuclease activity as reported previously, but also possesses a flap-endonuclease activity. Our study indicates that Exo1p shares similar, but not identical structure-function relationships to other characterized members of the Rad2p family in the N and I nuclease domains. The two exo1p mutants we examined, showed deficiencies for both double-stranded DNA (dsDNA) 5'-3' exonuclease and flap-endonuclease activities. Examining the genetic interaction of these two exo1 mutations with rad27Delta suggest that the Exo1p flap-endonuclease activity and not the dsDNA 5'-3' exonuclease is redundant to Rad27p for viability. In addition, our in vivo results also indicate that many exo1Delta phenotypes are dependent on the complete catalytic activities of Exo1p. Finally, our findings plus those of other investigators suggest that Exolp functions both in a catalytic and a structural capacity during DNA MMR. (C) 2002 Elsevier Science B.V. All rights reserved.