Human Cells Require Non-stop Ribosome Rescue Activity in Mitochondria
Human Cells Require Non-stop Ribosome Rescue Activity in Mitochondria
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DOI：
10.1371/journal.pgen.1005964
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发表时间：
2016-03-01
期刊：
影响因子：
4.5
通讯作者：
Keiler, Kenneth C.
中科院分区：
文献类型：
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作者：
Feaga, Heather A.;Quickel, Michael D.;Keiler, Kenneth C.
细菌使用反式翻译和替代拯救因子ArfA（P36675）和ArfB（Q9 A8 Y3）来水解核糖体上的肽基-tRNA，所述核糖体在蛋白质合成期间在mRNA的3'末端附近停滞。真核蛋白ICT 1（Q14197）与ArfB同源。在体外核糖体拯救分析的人ICT 1和新月柄杆菌ArfB表明，这些蛋白具有相同的活性和底物特异性。ArfB和ICT 1都能水解不间断核糖体上的肽基-tRNA，或在A位点后14个核苷酸处停滞的核糖体上的肽基-tRNA。ICT 1提供了足够的核糖体拯救活性以支持C.缺乏反式翻译和ArfB的crescentus细胞。同样，当ICT 1被siRNA沉默时，ArfB的表达保护人类细胞免于死亡。这些数据表明ArfB和ICT 1在功能上是可互换的，并证明ICT 1是核糖体拯救因子。由于ICT 1在人类细胞中是必不可少的，这些结果表明线粒体中的核糖体拯救活性在人类中是必需的。
Bacteria use trans-translation and the alternative rescue factors ArfA (P36675) and ArfB (Q9A8Y3) to hydrolyze peptidyl-tRNA on ribosomes that stall near the 3' end of an mRNA during protein synthesis. The eukaryotic protein ICT1 (Q14197) is homologous to ArfB. In vitro ribosome rescue assays of human ICT1 and Caulobacter crescentus ArfB showed that these proteins have the same activity and substrate specificity. Both ArfB and ICT1 hydrolyze peptidyl-tRNA on nonstop ribosomes or ribosomes stalled with = 14 nucleotides past the A site. ICT1 provided sufficient ribosome rescue activity to support viability in C. crescentus cells that lacked both trans-translation and ArfB. Likewise, expression of ArfB protected human cells from death when ICT1 was silenced with siRNA. These data indicate that ArfB and ICT1 are functionally interchangeable, and demonstrate that ICT1 is a ribosome rescue factor. Because ICT1 is essential in human cells, these results suggest that ribosome rescue activity in mitochondria is required in humans.