Ribosome release factor RF4 and termination factor RF3 are involved in dissociation of peptidyl-tRNA from the ribosome
Ribosome release factor RF4 and termination factor RF3 are involved in dissociation of peptidyl-tRNA from the ribosome
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DOI：
10.1093/emboj/17.3.808
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发表时间：
1998-02-02
期刊：
影响因子：
11.4
通讯作者：
Buckingham, RH
中科院分区：
文献类型：
--
作者：
Heurgué-Hamard, V;Karimi, R;Buckingham, RH
肽基-tRNA从核糖体解离是伴随正常蛋白质合成的能量昂贵但显然不可避免的过程。这些事件的脱落产物被肽基-tRNA水解酶水解。已经进行了突变体选择以鉴定参与肽基-tRNA脱落的基因，使用大肠杆菌中的热敏肽基-tRNA水解酶突变体，frr基因上游的转座子插入，编码RF 4插入损害了frr基因的表达，突变失活了编码RF 3的prfC，相反，从质粒产生RF 4增加了肽基-tRNA水解酶突变体的热敏性，在终止信号或有义密码子处暂停的肽基-tRNA从核糖体释放的体外测量证实了RF 3和RF 4能够刺激肽基-tRNA从核糖体释放，并且表明RF 4的这种作用需要易位因子EF 2的存在，已知在核糖体再循环中需要RF 4的功能，当一起存在时，三种因子能够刺激释放高达12倍。有人建议，RF 4可能取代肽基-tRNA从核糖体的方式有关的建议功能，在核糖体回收过程中去除脱酰tRNA。
Peptidyl-tRNA dissociation from ribosomes is an energetically costly but apparently inevitable process that accompanies normal protein synthesis, The drop-off products of these events are hydrolysed by peptidyl-tRNA hydrolase, Mutant selections have been made to identify genes involved in the drop-off of peptidyl-tRNA, using a thermosensitive peptidyl-tRNA hydrolase mutant in Escherichia coli, Transposon insertions upstream of the frr gene, which encodes RF4 (ribosome release or recycling factor), restored growth to this mutant, The insertions impaired expression of the frr gene, Mutations inactivating prfC, encoding RF3 (release factor 3), displayed a similar phenotype, Conversely, production of RF4 from a plasmid increased the thermosensitivity of the peptidyl-tRNA hydrolase mutant, In vitro measurements of peptidyl-tRNA release from ribosomes paused at stop signals or sense codons confirmed that RF3 and RF4 were able to stimulate peptidyl-tRNA release from ribosomes, and showed that this action of RF4 required the presence of translocation factor EF2, known to be needed for the function of RF4 in ribosome recycling, When present together, the three factors were able to stimulate release up to 12-fold. It is suggested that RF4 may displace peptidyl-tRNA from the ribosome in a manner related to its proposed function in removing deacylated tRNA during ribosome recycling.