Oligomerization of human Gadd45a protein
Oligomerization of human Gadd45a protein
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DOI：
10.1074/jbc.m105115200
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发表时间：
2001-10-19
影响因子：
4.8
通讯作者：
Fornace, AJ
中科院分区：
文献类型：
--
作者：
Kovalsky, O;Lung, FDT;Fornace, AJ
Gadd45a是一种18 kDa的酸性蛋白，由基因毒性和某些其他细胞应激诱导。这种蛋白质的确切功能尚不清楚。然而，有证据表明它参与了生长控制、维持基因组稳定性、DNA修复、细胞周期控制和细胞凋亡。Gadd45a在体外和/或体内一直被证明与一些在这些细胞过程中发挥核心作用的蛋白质相互作用：增殖细胞核抗原、p21(Cip1/Waf1)、CDc2-CyclinB复合体、MTK1和病史。增加这一复杂性的是，我们发现Gadd45a在溶液中自结合，无论是在体外还是在细胞中表达时都是如此。此外，Gadd45a可以与GADD45家族的另外两个成员，人Gadd45b(MyD118)和Gadd45g(CR6)复合。凝胶排斥层析、天然凝胶电泳法、酶联免疫吸附实验和化学交联实验表明，重组Gadd45a在体外形成二聚体、三聚体和四聚体，其中以二聚体为主。缺失突变和多肽扫描分析表明，Gadd45a有两个自结合位点：N端33-61位氨基酸和40位C端氨基酸。尽管Gadd45a在细胞中的丰度很低，但在过度表达时，蛋白质形成的灶状核结构中可能会达到低聚物形成浓度。Gadd45a自结合在改变受损核小体DNA可及性方面的潜在作用的证据被提出。
Gadd45a is an 18-kDa acidic protein that is induced by genotoxic and certain other cellular stresses. The exact function of this protein is not known. However, there is evidence for its involvement in growth control, maintenance of genomic stability, DNA repair, cell cycle control, and apoptosis. Consistently, Gadd45a has previously been shown to interact in vitro and/or in vivo with a number of proteins playing central roles in these cellular processes: proliferating cell nuclear antigen, p21(Cip1/Waf1), Cdc2-CyclinB complex, MTK1, and histories. Adding to this complexity, we have found that Gadd45a self-associates in solution, both in vitro and when expressed in the cell. Moreover, Gadd45a can complex with the two other members of the Gadd45 family of stress-induced proteins, human Gadd45b (MyD118) and Gadd45g (CR6). Gel-exclusion chromatography, native gel electrophoretic analysis, enzyme-linked immunosorbent assay, and chemical cross-linking showed that recombinant Gadd45a forms dimeric, trimeric, and tetrameric species in vitro, the dimers being the predominant form. Deletion mutant and peptide scanning analyses suggest that Gadd45a has two self-association sites: within N-terminal amino acids 33-61 and within 40 C-terminal amino acids. Despite the low abundance of Gadd45a in the cell, oligomer-forming concentrations can probably be achieved in the foci-like nuclear structures formed by the protein upon overexpression. Evidence for a potential role of Gadd45a self-association in altering DNA accessibility on damaged nucleosomes is presented.