Rousset R, Desbois C, Bantignies F, Jalinot P
CNRS UMR49, Ecole Normale Supérieure de Lyon, France.
Nature. 1996 May 23;381(6580):328-31. doi: 10.1038/381328a0.
The viral Tax protein, which is encoded by human T-cell leukaemia virus HTLV-I, activates nuclear translocation of the NF-kappa B/Rel transcription factors and relieves cytoplasmic sequestration of RelA and Rel by heterodimerization with NF-kappa B1/p1O5 (refs 1,2). Proteolytic maturation of this precursor protein is performed by the proteasome complex. Here we show that Tax binds specifically to two subunits of the 20S proteasome, HsN3 and HC9. This interaction is weakened with HsN3 and lost for HC9 when a mutant of Tax is substituted that is selectively defective for NF-kappa B activation. Immunoprecipitation shows that p1O5 binds weakly to HC9 and that this interaction is reinforced by Tax. No bridging function of Tax between p1O5 and HsN3 was observed. From these results, we propose that Tax accelerates the proteolytic maturation of P105 by favouring its anchorage to the proteasome.
由人类T细胞白血病病毒HTLV-I编码的病毒Tax蛋白，可激活NF-κB/Rel转录因子的核转位，并通过与NF-κB1/p105异二聚化解除RelA和Rel在细胞质中的隔离（参考文献1,2）。这种前体蛋白的蛋白水解成熟是由蛋白酶体复合物完成的。在此我们表明，Tax特异性结合20S蛋白酶体的两个亚基HsN3和HC9。当用对NF-κB激活有选择性缺陷的Tax突变体替代时，这种相互作用与HsN3减弱，与HC9则消失。免疫沉淀显示p105与HC9弱结合，且这种相互作用因Tax而增强。未观察到Tax在p105和HsN3之间的桥接功能。根据这些结果，我们提出Tax通过促进P105锚定到蛋白酶体来加速其蛋白水解成熟。
