Department of Biological Sciences, Columbia University, New York, NY 10027, USA.
Mol Cell. 2013 Jan 10;49(1):7-17. doi: 10.1016/j.molcel.2012.11.005. Epub 2012 Dec 6.
The 3' ends of most eukaryotic mRNAs are produced by an endonucleolytic cleavage followed by synthesis of a poly(A) tail. Poly(A) polymerase (PAP), the enzyme that catalyzes the formation of the tail, is subject to tight regulation involving several posttranslational modifications. Here we show that the enzyme poly(ADP-ribose) polymerase 1 (PARP1) modifies PAP and regulates its activity both in vitro and in vivo. PARP1 binds to and modifies PAP by poly(ADP-ribosyl)ation (PARylation) in vitro, which inhibits PAP activity. In vivo we show that PAP is PARylated during heat shock, leading to inhibition of polyadenylation in a PARP1-dependent manner. The observed inhibition reflects reduced RNA binding affinity of PARylated PAP in vitro and decreased PAP association with non-heat shock protein-encoding genes in vivo. Our results provide direct evidence that PARylation can control processing of mRNA precursors, and also identify PARP1 as a regulator of polyadenylation during thermal stress.
大多数真核生物 mRNA 的 3' 端是通过内切核酸酶切割，然后合成多聚（A）尾产生的。多聚（A）聚合酶（PAP）是催化尾巴形成的酶，其受到涉及多种翻译后修饰的严格调控。在这里，我们表明，酶多聚（ADP-核糖）聚合酶 1（PARP1）修饰 PAP，并在体外和体内调节其活性。PARP1 通过体外的多聚（ADP-核糖）化（PARylation）结合并修饰 PAP，从而抑制 PAP 活性。我们体内研究表明，在热休克过程中，PAP 发生 PARylation，导致以 PARP1 依赖的方式抑制多聚腺苷酸化。观察到的抑制作用反映了 PARylated PAP 在体外的 RNA 结合亲和力降低，以及 PAP 在体内与非热休克蛋白编码基因的结合减少。我们的结果提供了直接证据，证明 PARylation 可以控制 mRNA 前体的加工，并且还确定 PARP1 是热应激过程中多聚腺苷酸化的调节剂。
