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Characterization of SMG7 14-3-3-like domain reveals phosphoserine binding-independent regulation of p53 and UPF1.
Scientific Reports ( IF 3.8 ) Pub Date : 2019-09-11 , DOI: 10.1038/s41598-019-49229-3
Lauren E Cowen 1 , Hongwei Luo 1 , Yi Tang 1
Affiliation  

The 14-3-3-related protein SMG7 plays critical roles in regulation of DNA damage response and nonsense-mediated mRNA decay (NMD). Like 14-3-3, SMG7 engages phosphoserine-dependent protein interactions; however, the precise role of phosphorylation-mediated SMG7 binding remains unknown. Here, we show that DNA damage-induced SMG7-p53 binding requires phosphorylated Ser15 on p53, and that substitution of the conserved lysine residue K66 in the SMG7 14-3-3-like domain with the glutamic acid (E) abolishes interactions with its client proteins p53 and UPF1. Unexpectedly, loss of phosphoserine-dependent SMG7 binding does not significantly affect p53 stabilization/activation, and p53-dependent cell growth arrest or apoptosis upon DNA damage. Also surprisingly, cells expressing the SMG7 K66E-knockin mutant retain fully functional UPF1-mediated NMD. These findings are highly unusual, given that phosphorylation-mediated 14-3-3 binding has essential roles in numerous cellular signaling pathways. Thus, our studies suggest that 14-3-3-like proteins such as SMG7 likely function using additional distinct regulatory mechanisms besides phosphoserine-mediated protein interactions.

中文翻译:

SMG7 14-3-3-like域的表征揭示了磷酸丝氨酸结合无关的p53和UPF1调节。

14-3-3-相关蛋白SMG7在调节DNA损伤反应和无义介导的mRNA衰变(NMD)中起着关键作用。像14-3-3一样,SMG7参与磷酸丝氨酸依赖性蛋白相互作用。然而,磷酸化介导的SMG7结合的确切作用仍然未知。在这里,我们显示DNA损伤诱导的SMG7-p53结合需要p53上的磷酸化Ser15,并且用谷氨酸(E)取代SMG7 14-3-3-like域中保守的赖氨酸残基K66消除了与其相互作用客户蛋白p53和UPF1。出乎意料的是,磷酸丝氨酸依赖性SMG7结合的丧失不会显着影响p53的稳定/激活,以及DNA损伤后p53依赖性细胞的生长停滞或凋亡。同样令人惊讶的是,表达SMG7 K66E基因敲入突变体的细胞保留了功能齐全的UPF1介导的NMD。鉴于磷酸化介导的14-3-3结合在众多细胞信号传导途径中起着至关重要的作用,因此这些发现是非常不寻常的。因此,我们的研究表明,除了磷酸丝氨酸介导的蛋白质相互作用以外,还可以使用其他独特的调控机制来发挥14-3-3-like蛋白(如SMG7)的作用。
更新日期:2019-09-11
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