GTP Hydrolysis by IF2 Guides Progression of the Ribosome into Elongation
GTP Hydrolysis by IF2 Guides Progression of the Ribosome into Elongation
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DOI：
10.1016/j.molcel.2009.06.008
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发表时间：
2009-07-10
期刊：
影响因子：
16
通讯作者：
Puglisi, Joseph D.
中科院分区：
文献类型：
--
作者：
Marshall, R. Andrew;Aitken, Colin Echeverria;Puglisi, Joseph D.
最近的结构数据揭示了核糖体在起始过程中的两种不同构象。我们采用单分子荧光方法来探测这些核糖体构象的动态关系在真实的时间。在没有起始因子的情况下，核糖体以两种不同的构象组装。起始因子引导核糖体发展为可以进入延伸周期的构象。特别是，IF2既加速了亚基连接的速率，又积极促进向可伸长构象的转变。通过IF2阻断GTP水解导致在构象中形成的70S复合物不能进入延伸。我们观察到，快速GTP水解IF2驱动过渡到可延伸的构象，从而使核糖体进入延长周期。
Recent structural data have revealed two distinct conformations of the ribosome during initiation. We employed single-molecule fluorescence methods to probe the dynamic relation of these ribosomal conformations in real time. In the absence of initiation factors, the ribosome assembles in two distinct conformations. The initiation factors guide progression of the ribosome to the conformation that can enter the elongation cycle. In particular, IF2 both accelerates the rate of subunit joining and actively promotes the transition to the elongation-competent conformation. Blocking GTP hydrolysis by IF2 results in 70S complexes formed in the conformation unable to enter elongation. We observe that rapid GTP hydrolysis by IF2 drives the transition to the elongation-competent conformation, thus committing the ribosome to enter the elongation cycle.