Archaeal translation initiation revisited:: The initiation factor 2 and eukaryotic initiation factor 2B α-β-δ subunit families
Archaeal translation initiation revisited:: The initiation factor 2 and eukaryotic initiation factor 2B α-β-δ subunit families
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DOI：
10.1073/pnas.95.7.3726
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发表时间：
1998-03-31
影响因子：
11.1
通讯作者：
Woese, CR
中科院分区：
文献类型：
--
作者：
Kyrpides, NC;Woese, CR
随着可用序列数据量的增加，很明显，我们对翻译起始的理解还远远不够全面，先前关于该过程起源的结论是错误的。与先前的结论相反，翻译起始的关键要素起源于普遍祖先阶段，因为同源对应物存在于所有三个主要类群中。在此，我探讨了细菌起始因子2（IF-2）和真核生物IF-2（eIF-2）/eIF-2B组分之间的进化关系，即，起始因子参与将起始tRNA引入翻译机制并进行肽链延伸循环的第一步。所有的大肠杆菌似乎都含有一个功能齐全的eIF-2分子，但它们缺乏相关的GTP再循环功能，eIF-2B（一个五亚基分子）。然而，eIF-2B亚基α、β和δ（相关）定义的基因家族的成员，尽管这些亚基与三个真核亚基中的任何一个都没有特异性相关。这个家族的其他成员也出现在一些（但绝不是所有）细菌中，甚至在声波真核生物中。该家族其他成员的功能意义尚不清楚，需要实验解决。类似地，在所有细菌和一些真核生物中出现的细菌IF-2样分子使翻译起始的情况进一步复杂化。总的来说，这些数据进一步支持了这样一种说法，即翻译起始的雏形出现在宇宙祖先阶段。
As the amount of available sequence data increases, it becomes apparent that our understanding of translation initiation is far from comprehensive and that prior conclusions concerning the origin of the process are wrong. Contrary to earlier conclusions, key elements of translation initiation originated at the Universal Ancestor stage, for homologous counterparts exist in all three primary taxa. Herein, me explore the evolutionary relationships among the components of bacterial initiation factor 2 (IF-2) and eukaryotic IF-2 (eIF-2)/eIF-2B, i.e., the initiation factors involved in introducing the initiator tRNA into the translation mechanism and performing the first step in the peptide chain elongation cycle. All Archaea appear to posses a fully functional eIF-2 molecule, hut they lack the associated GTP recycling function, eIF-2B (a five-subunit molecule). Yet, the Archaea do posses members of the gene family defined by the (related) eIF-2B subunits alpha, beta, and delta, although these are not specifically related to any of the three eukaryotic subunits. Additional members of this family also occur in some (but by no means all) Bacteria and even in sonic eukaryotes. The functional significance of the other members of this family is unclear and requires experimental resolution. Similarly, the occurrence of bacterial IF-2-like molecules in all Archaea and in some eukaryotes further complicates the picture of translation initiation. Overall, these data lend further support to the suggestion that the rudiments of translation initiation were present at the Universal Ancestor stage.