磷酸化对UCHL3体外去泛素化酶活性的影响
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摘要
泛素羧基末端水解酶L3(ubiquitin C-terminal hydrolase-L3,UCHL3)是真核细胞泛素羧基末端水解酶家族(ubiquitin C-terminal hydrolases,UCHs)的重要成员,参与了DNA损伤修复等过程。近期研究表明,UCHL3不仅在体外条件下可以切割C端用香豆素修饰的泛素分子(C-terminal conjugate of ubiquitin with 7-amino-4-methylcoumarin,Ub-AMC),当UCHL3上第75位的丝氨酸(Ser75)发生磷酸化后,其在细胞内切割多聚泛素链的活性也明显增强,但这种磷酸化调控尚缺乏体外证据支持。基于此,利用点突变及多种层析技术制备了野生型UCHL3(UCHL3~(WT))和模拟磷酸化的UCHL3蛋白(UCHL3~(S75E)),在体外生化水平上研究了磷酸化对UCHL3的泛素链切割活性的影响。体外泛素切割实验显示,与UCHL3~(WT)相比,UCHL3~(S75E)切割Ub-AMC的活性提高了70%,但仍不能展现生理水平上的二泛素(di-ubiquitin,diub)切割活性,暗示UCHL3切割泛素链的机制更为复杂。同时,系统发育树与序列对比分析显示,发生磷酸化的Ser75仅存在于UCHL3中,在其他UCH家族成员中并不保守,表明基于Ser75的磷酸化调控是UCHL3所特有的。此外,UCHL3在众多真核生物中高度保守,暗示着该蛋白的磷酸化调控机制在进化上的保守性。研究结果拓展了对UCHL3磷酸化修饰调控的认识,为深入研究其生理角色奠定了基础。
Ubiquitin C-terminal hydropase-L3(UCHL3), an important member of the ubiquitin C-terminal hydrolases(UCHs) family, is involved in DNA damage repair and other processes. Previous studies showed that UCHL3 can cleave C-terminal conjugate of ubiquitin with 7-amino-4-methylcoumarin(Ub-AMC) in vitro and the phosphorylation of Ser75 obviously promotes the cleavage activity of UCHL3 towards poly-ubiquitin chains in vivo. But this regulation has not been corroborated by any biochemical data in vitro so far. Based on this situation, wild-type UCHL3(UCHL3~(WT)) and simulated phosphorylated UCHL3 protein(UCHL3~(S75 E)) were prepared by QuikChange site-directed mutagenesis technique and step-wise chromatography methods. The effect of phosphorylation at Ser75 on the poly-ubiquitin chains cleavage activity of UCHL3 in vitro was studied. The results showed that purified UCHL3~(S75 E) displayed the enhancing cleavage activity towards Ub-AMC compared to UCHL3~(WT) by 70%, but no physiological level activity to di-ubiquitin(diub) chains, which suggested that the mechanism by which UCHL3 cuts ubiquitin chains might be more complex. Meanwhile, sequence alignment and phylogenetic trees analysis showed that the phosphorylated Ser75 only existed in UCHL3 but not in other UCH family members, indicating that the phosphorylation regulation based on Ser75 probably was unique to UCHL3. In addition, UCHL3 was highly conserved in various eukaryotic organisms, implying that the phosphorylation regulation mechanism of UCHL3 was highly conserved in evolution. The results of this research expanded the understanding of the phosphorylation regulation of UCHL3 and laid a foundation for further understanding of its physiological role.
Ubiquitin C-terminal hydropase-L3(UCHL3), an important member of the ubiquitin C-terminal hydrolases(UCHs) family, is involved in DNA damage repair and other processes. Previous studies showed that UCHL3 can cleave C-terminal conjugate of ubiquitin with 7-amino-4-methylcoumarin(Ub-AMC) in vitro and the phosphorylation of Ser75 obviously promotes the cleavage activity of UCHL3 towards poly-ubiquitin chains in vivo. But this regulation has not been corroborated by any biochemical data in vitro so far. Based on this situation, wild-type UCHL3(UCHL3~(WT)) and simulated phosphorylated UCHL3 protein(UCHL3~(S75 E)) were prepared by QuikChange site-directed mutagenesis technique and step-wise chromatography methods. The effect of phosphorylation at Ser75 on the poly-ubiquitin chains cleavage activity of UCHL3 in vitro was studied. The results showed that purified UCHL3~(S75 E) displayed the enhancing cleavage activity towards Ub-AMC compared to UCHL3~(WT) by 70%, but no physiological level activity to di-ubiquitin(diub) chains, which suggested that the mechanism by which UCHL3 cuts ubiquitin chains might be more complex. Meanwhile, sequence alignment and phylogenetic trees analysis showed that the phosphorylated Ser75 only existed in UCHL3 but not in other UCH family members, indicating that the phosphorylation regulation based on Ser75 probably was unique to UCHL3. In addition, UCHL3 was highly conserved in various eukaryotic organisms, implying that the phosphorylation regulation mechanism of UCHL3 was highly conserved in evolution. The results of this research expanded the understanding of the phosphorylation regulation of UCHL3 and laid a foundation for further understanding of its physiological role.
引文
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[20] Nishi R,Wijnhoven P W G,Kimura Y,et al..The deubiquitylating enzyme UCHL3 regulates Ku80 retention at sites of DNA damage[J].Sci.Rep.,2018,8(1):17891.
[21] Branzei D.Ubiquitin family modifications and template switching[J].FEBS Lett.,2011,585(18):2810-2817.
[22] Xu D,Shan B,Lee B H,et al..Phosphorylation and activation of ubiquitin-specific protease-14 by Akt regulates the ubiquitin-proteasome system[J].Elife,2015,4:e10510.
[2] Clague M J,Urbé S.Integration of cellular ubiquitin and membrane traffic systems:Focus on deubiquitylases[J].FEBS J.,2017,284(12):1753-1766.
[3] Heideker J,Wertz I E.DUBs,the regulation of cell identity and disease[J].Biochem.J.,2015,467(1):191.
[4] Kee Y,Huang T T.Role of deubiquitinating enzymes in DNA repair[J].Mol.Cell.Biol.,2016,36(4):524-544.
[5] Komander D,Rape M.The ubiquitin code[J].Annu.Rev.Biochem.,2012,81:203-229.
[6] Swatek K N,Komander D.Ubiquitin modifications[J].Cell Res.,2016,26(4):399-422.
[7] Clague M J,Barsukov I,Coulson J M,et al..Deubiquitylases from genes to organism[J].Physiol.Rev.,2013,93(3):1289-1315.
[8] Komander D,Clague M J,Urbé S.Breaking the chains:Structure and function of the deubiquitinases[J].Nat.Rev.Mol.Cell Biol.,2009,10(8):550-563.
[9] Reyes-Turcu F E,Ventii K H,Wilkinson K D.Regulation and cellular roles of ubiquitin-specific deubiquitinating enzymes[J].Annu.Rev.Biochem.,2009,78:363-397.
[10] Zhao P,Guo T,Qian L,et al..Ubiquitin C-terminal hydrolase-L3 promotes interferon antiviral activity by stabilizing type I-interferon receptor[J].Antivir.Res.,2017,144:120-129.
[11] Kim J Y,Lee J M,Cho J Y.Ubiquitin C-terminal hydrolase-L3 regulates Smad1 ubiquitination and osteoblast differentiation[J].FEBS Lett.,2011,585(8):1121-1126.
[12] Miyoshi Y,Nakayama S,Torikoshi Y,et al..High expression of ubiquitin carboxy-terminal hydrolase -L1 and -L3 mRNA predicts early recurrence in patients with invasive breast cancer[J].Cancer Sci.,2006,97(6):523-529.
[13] Luo K,Li L,Li Y,et al..A phosphorylation-deubiquitination cascade regulates the BRCA2-RAD51 axis in homologous recombination[J].Genes Dev.,2016,30(23):2581-2595.
[14] Liao C,Beveridge R,Hudson J J R,et al..UCHL3 regulates topoisomerase-induced chromosomal break repair by controlling TDP1 proteostasis[J].Cell Rep.,2018,23(11):3352-3365.
[15] Pan M,Gao S,Zheng Y,et al..Quasi-racemic X-ray structures of K27-linked ubiquitin chains prepared by total chemical synthesis[J].J.Am.Chem.Soc.,2016,138(23):7429-7435.
[16] Bett J S,Ritorto M S,Ewan R,et al..Ubiquitin C-terminal hydrolases cleave isopeptide-and peptide-linked ubiquitin from structured proteins but do not edit ubiquitin homopolymers[J].Biochem.J.,2015,466(3):489-498.
[17] Xu D,Shan B,Sun H,et al..USP14 regulates autophagy by suppressing K63 ubiquitination of Beclin 1[J].Genes Dev.,2016,30(15):1718-1730.
[18] Lee B H,Lee M J,Park S,et al..Enhancement of proteasome activity by a small-molecule inhibitor of USP14[J].Nature,2010,467(7312):179-184.
[19] Pan M,Zheng Q,Ding S,et al..Chemical protein synthesis enabled mechanistic studies on the molecular recognition of K27-linked ubiquitin chains[J].Angew.Chem.Int.Ed.Engl.,2019,58(9):2627-2631.
[20] Nishi R,Wijnhoven P W G,Kimura Y,et al..The deubiquitylating enzyme UCHL3 regulates Ku80 retention at sites of DNA damage[J].Sci.Rep.,2018,8(1):17891.
[21] Branzei D.Ubiquitin family modifications and template switching[J].FEBS Lett.,2011,585(18):2810-2817.
[22] Xu D,Shan B,Lee B H,et al..Phosphorylation and activation of ubiquitin-specific protease-14 by Akt regulates the ubiquitin-proteasome system[J].Elife,2015,4:e10510.
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