PROKARYOTIC RIBOSOMES RECODE THE HIV-1 GAG-POL-1 FRAMESHIFT SEQUENCE BY AN E/P SITE POST-TRANSLOCATION SIMULTANEOUS SLIPPAGE MECHANISM
PROKARYOTIC RIBOSOMES RECODE THE HIV-1 GAG-POL-1 FRAMESHIFT SEQUENCE BY AN E/P SITE POST-TRANSLOCATION SIMULTANEOUS SLIPPAGE MECHANISM
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DOI：
10.1093/nar/23.9.1487
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发表时间：
1995-05-11
影响因子：
14.9
通讯作者：
TATE, WP
中科院分区：
文献类型：
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作者：
HORSFIELD, JA;WILSON, DN;TATE, WP
在典型逆转录病毒位点上有利于-1移码的机制是预易位同时滑移模型。另一种后易位机制也会在移码位点上产生相同的蛋白质序列，因此在本研究中，终止密码子的战略位置已被用来区分这两种机制。来自 HIV-1 gag-pol 重叠的 26 个碱基对移码序列已被修改，以包含紧邻七核苷酸移码信号 3' 的终止密码子，该位置通常天然存在于逆转录病毒重新编码位点中。七核苷酸序列3'端的终止密码子降低了原核生物核糖体上的移码效率，并且当体内释放因子水平增加时，重新编码事件进一步受到抑制，在缺陷释放因子2水平升高的情况下，含有由该释放因子特异性识别的终止密码子的构建体中体内移码效率增加。这些结果与七核苷酸滑动序列的最后六个核苷酸占据核糖体E和P位点而不是P和A位点一致，下一个密码子占据A位点，因此具有易位后而不是易位前-1滑动模型。
The mechanism favoured for -1 frameshifting at typical retroviral sites is a pre-translocation simultaneous slippage model. An alternative post-translocation mechanism would also generate the same protein sequence across the frameshift site and therefore in this study the strategic placement of a stop codon has been used to distinguish between the two mechanisms. A 26 base pair frameshift sequence from the HIV-1 gag-pol overlap has been modified to include a stop codon immediately 3' to the heptanucleotide frameshift signal, where it often occurs naturally in retroviral recoding sites. Stop codons at the 3'-end of the heptanucleotide sequence decreased the frameshifting efficiency on prokaryote ribosomes and the recoding event was further depressed when the levels of the release factors in vivo were increased, in the presence of elevated levels of a defective release factor 2, frameshifting efficiency in vivo was increased in the constructs containing the stop codons recognized specifically by that release factor. These results are consistent with the last six nucleotides of the heptanucleotide slippery sequence occupying the ribosomal E and P sites, rather than the P and A sites, with the next codon occupying the A site and therefore with a post-translocation rather than a pre-translocation -1 slippage model.