Dynamic regulation of Pif1 acetylation is crucial to the maintenance of genome stability.
Dynamic regulation of Pif1 acetylation is crucial to the maintenance of genome stability.
复制标题
Pif1乙酰化的动态调节对于维持基因组稳定性至关重要。
DOI：
10.1007/s00294-020-01116-5
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发表时间：
2021-03
期刊：
影响因子：
2.5
通讯作者：
Balakrishnan L
中科院分区：
文献类型：
--
作者：
Ononye OE;Sausen CW;Bochman ML;Balakrishnan L
PIF1家族解旋酶在原核生物和真核生物中进化保守。这些酶通过参与多种DNA交易来支持基因组的完整性，这些交易可以广泛地分为DNA复制、DNA修复和端粒维护角色。然而，必须仔细控制细胞中PIF1的活性水平，因为Pif1在酿酒酵母中过表达是有毒的，而敲除或过表达人PIF1(HPIF1)支持癌细胞生长。这表明PIF1家族解旋酶必须在体内受到严格的调控，以将它们的活性引导到需要它们的地方和时间，并将这些活性维持在适当的动态平衡水平。前人的工作表明，酿酒酵母Pif1的C末端磷酸化调节其端粒维持活性，我们最近发现Pif1也受赖氨酸乙酰化的调节。在缺乏Rpd3赖氨酸脱乙酰酶的细胞中，Pif1的过度表达毒性加剧，但NuA4赖氨酸乙酰基转移酶亚单位Esa1的突变减轻了这种毒性。利用重组蛋白，我们发现乙酰化增强了Pif1的DNA结合亲和力、ATPase活性和DNA解离活性。解旋酶的三个结构域都是体外乙酰化的靶点，多条证据表明，乙酰化驱动了Pif1 N末端结构域的构象变化，从而影响了这种刺激。目前尚不清楚是什么触发了Pif1的赖氨酸乙酰化，以及这种修饰如何影响解旋酶的许多体内功能，但未来的工作有望阐明这种蛋白质是如何在细胞内受到严格调控的。
PIF1 family helicases are evolutionarily conserved among prokaryotes and eukaryotes. These enzymes function to support genome integrity by participating in multiple DNA transactions that can be broadly grouped into DNA replication, DNA repair, and telomere maintenance roles. However, the levels of PIF1 activity in cells must be carefully controlled, as Pif1 over-expression in Saccharomyces cerevisiae is toxic, and knockdown or over-expression of human PIF1 (hPIF1) supports cancer cell growth. This suggests that PIF1 family helicases must be subject to tight regulation in vivo to direct their activities to where and when they are needed, as well as to maintain those activities at proper homeostatic levels. Previous work shows that C-terminal phosphorylation of S. cerevisiae Pif1 regulates its telomere maintenance activity, and we recently identified that Pif1 is also regulated by lysine acetylation. The over-expression toxicity of Pif1 was exacerbated in cells lacking the Rpd3 lysine deacetylase, but mutation of the NuA4 lysine acetyltransferase subunit Esa1 ameliorated this toxicity. Using recombinant proteins, we found that acetylation stimulated the DNA binding affinity, ATPase activity, and DNA unwinding activities of Pif1. All three domains of the helicase were targets of acetylation in vitro, and multiple lines of evidence suggest that acetylation drives a conformational change in the N-terminal domain of Pif1 that impacts this stimulation. It is currently unclear what triggers lysine acetylation of Pif1 and how this modification impacts the many in vivo functions of the helicase, but future work promises to shed light on how this protein is tightly regulated within the cell.
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