Morrissey Catherine, Schwefel David, Ennis-Adeniran Valerie, Taylor Ian A, Crow Yanick J, Webb Michelle
*Genetic Medicine, University of Manchester, Manchester Academic Health Science Centre, Central Manchester Foundation Trust University Hospitals, Manchester M13 9PT, U.K.
†Division of Molecular Structure, MRC National Institute for Medical Research, the Ridgeway, Mill Hill, London NM7 1AA, U.K.
Biochem J. 2015 Feb 15;466(1):69-76. doi: 10.1042/BJ20140203.
Mutations in SAMHD1 cause Aicardi-Goutières syndrome (AGS), a Mendelian inflammatory disease which displays remarkable clinical and biochemical overlap with congenital viral infection. SAMHD1 (SAM domain and HD domain-containing protein 1) has also been defined as an HIV-1 restriction-factor that, through a novel triphosphohydrolase activity, inhibits early stage HIV-1 replication in myeloid-derived dendritic cells (MDDCs), macrophages and resting CD4+ T-cells. The potent activity of SAMHD1 is likely to be the subject of a variety of regulatory mechanisms. Knowledge of proteins that interact with SAMHD1 may not only enhance our understanding of the pathogenesis of AGS, but may also provide further details on the link between the regulation of cellular dNTPs and HIV-1 restriction. In the present study, we used a yeast two-hybrid screen and pull-down analysis followed by MS to identify the eukaryotic elongation factor 1A1 (eEF1A1) as a potential interaction partner of SAMHD1. This interaction was confirmed by unbiased co-immunoprecipitation and demonstrated in situ by a proximity ligation assay (PLA). We show that this interaction is enhanced in mutant SAMHD1 cell lines and suggest that eEF1A1 may mediate SAMHD1 turnover by targeting it to the proteosome for degradation through association with Cullin4A and Rbx1.
SAMHD1基因的突变会导致Aicardi-Goutières综合征（AGS），这是一种孟德尔遗传性炎症性疾病，在临床和生化方面与先天性病毒感染有显著重叠。SAMHD1（含SAM结构域和HD结构域蛋白1）也被定义为一种HIV-1限制因子，它通过一种新的三磷酸水解酶活性，抑制HIV-1在髓系来源的树突状细胞（MDDC）、巨噬细胞和静息CD4+T细胞中的早期复制。SAMHD1的强大活性可能受到多种调控机制的影响。了解与SAMHD1相互作用的蛋白质不仅可能增进我们对AGS发病机制的理解，还可能提供有关细胞dNTP调节与HIV-1限制之间联系的更多细节。在本研究中，我们使用酵母双杂交筛选和下拉分析，随后进行质谱分析，以鉴定真核延伸因子1A1（eEF1A1）作为SAMHD1的潜在相互作用伙伴。这种相互作用通过无偏差的共免疫沉淀得到证实，并通过邻近连接分析（PLA）在原位得到证明。我们表明，这种相互作用在突变型SAMHD1细胞系中增强，并表明eEF1A1可能通过与Cullin4A和Rbx1结合，将SAMHD1靶向蛋白酶体进行降解，从而介导SAMHD1的周转。
