Pif1 family DNA helicases: A helpmate to RNase H?
Pif1 family DNA helicases: A helpmate to RNase H?
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DOI：
10.1016/j.dnarep.2019.06.004
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发表时间：
2019-12-01
期刊：
影响因子：
3.8
通讯作者：
Zakian, Virginia A.
中科院分区：
文献类型：
--
作者：
Pohl, Thomas J.;Zakian, Virginia A.
R环是一种结构，当RNA转录本与编码它的DNA链结合时，使互补链暴露为单链DNA环。当RNA转录本的处理受到损害时，R环就会积累起来。如果不能移除这些RNA-DNA杂交体，可能会导致复制分叉停滞和基因组不稳定。R-环的分解被认为主要是由RNaseH酶通过去除和降解杂交中的RNA来介导的。然而，DNA解旋酶也可以通过取代结合的RNA来拆除R-环。特别是，Pif1家族DNA解旋酶已经被证明在特定的基因组座位上调节R-环的形成，例如tRNA基因和着丝粒。在这里，我们综述了Pif1家族解旋酶在体内和体外的作用，并讨论了Pif1家族解旋酶作用于RNA-DNA杂交物的证据，并强调了它们在补充RNaseH以解析R-环方面的潜在作用。
An R-loop is a structure that forms when an RNA transcript stays bound to the DNA strand that encodes it and leaves the complementary strand exposed as a loop of single stranded DNA. R-loops accumulate when the processing of RNA transcripts is impaired. The failure to remove these RNA-DNA hybrids can lead to replication fork stalling and genome instability. Resolution of R-loops is thought to be mediated mainly by RNase H enzymes through the removal and degradation of the RNA in the hybrid. However, DNA helicases can also dismantle R-loops by displacing the bound RNA. In particular, the Pif1 family DNA helicases have been shown to regulate R-loop formation at specific genomic loci, such as tRNA genes and centromeres. Here we review the roles of Pif1 family helicases in vivo and in vitro and discuss evidence that Pif1 family helicases act on RNA-DNA hybrids and highlight their potential roles in complementing RNase H for R-loop resolution.