ABCE1 在真核生物终止后核糖体循环中的作用。
The role of ABCE1 in eukaryotic posttermination ribosomal recycling.
机构信息
Department of Cell Biology, SUNY Downstate Medical Center, 450 Clarkson Avenue, Brooklyn, NY 11203, USA.
出版信息
Mol Cell. 2010 Jan 29;37(2):196-210. doi: 10.1016/j.molcel.2009.12.034.
After termination, eukaryotic 80S ribosomes remain associated with mRNA, P-site deacylated tRNA, and release factor eRF1 and must be recycled by dissociating these ligands and separating ribosomes into subunits. Although recycling of eukaryotic posttermination complexes (post-TCs) can be mediated by initiation factors eIF3, eIF1, and eIF1A (Pisarev et al., 2007), this energy-free mechanism can function only in a narrow range of low Mg(2+) concentrations. Here, we report that ABCE1, a conserved and essential member of the ATP-binding cassette (ABC) family of proteins, promotes eukaryotic ribosomal recycling over a wide range of Mg(2+) concentrations. ABCE1 dissociates post-TCs into free 60S subunits and mRNA- and tRNA-bound 40S subunits. It can hydrolyze ATP, GTP, UTP, and CTP. NTP hydrolysis by ABCE1 is stimulated by post-TCs and is required for its recycling activity. Importantly, ABCE1 dissociates only post-TCs obtained with eRF1/eRF3 (or eRF1 alone), but not post-TCs obtained with puromycin in eRF1's absence.
终止后，真核 80S 核糖体仍然与 mRNA、P 位去酰化的 tRNA 和释放因子 eRF1 结合在一起，必须通过解离这些配体并将核糖体分离成亚基来循环利用。尽管真核终止后复合物（post-TCs）的循环可以由起始因子 eIF3、eIF1 和 eIF1A 介导（Pisarev 等人，2007 年），但这种无能量的机制只能在低 Mg(2+)浓度的狭窄范围内发挥作用。在这里，我们报告说 ABCE1，一种保守且必需的 ATP 结合盒（ABC）蛋白家族成员，在广泛的 Mg(2+)浓度范围内促进真核核糖体的循环利用。ABCE1 将 post-TCs 解离成游离的 60S 亚基和与 mRNA 和 tRNA 结合的 40S 亚基。它可以水解 ATP、GTP、UTP 和 CTP。ABCE1 对 post-TCs 的 NTP 水解受到刺激，并且是其循环利用活性所必需的。重要的是，ABCE1 仅解离与 eRF1/eRF3（或仅 eRF1）获得的 post-TCs，而不与 eRF1 缺失时用 puromycin 获得的 post-TCs 解离。
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