Metabolite channeling in the origin of life
Metabolite channeling in the origin of life
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DOI：
10.1006/jtbi.1996.0070
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发表时间：
1996-04-21
影响因子：
2
通讯作者：
Edwards, MR
中科院分区：
文献类型：
--
作者：
Edwards, MR
生命起源的一个核心问题涉及原始代谢物和催化剂是否如人们经常设想的那样在溶液中随机相互作用，或者它们是否从一开始就排列在有序的代谢复合物中。后一种可能性与现存细胞中代谢物通道的假设一致，该假设认为许多途径中的中间体在途径酶之间直接转移，而不进行扩散。在此基础上提出了一个模型，其中生命起源于 FeS2（黄铁矿）矿物表面组织的代谢复合物中的自养自养。由于代谢物和催化剂产生于这些复合物的特定位点，因此在具有精确底物结合位点的蛋白酶存在之前，它们可以在进化途径中与邻近物种发生特异性相互作用。在连续的阶段中，RNA 催化剂和蛋白酶可以合并到这些阵列中。整个过程可以被视为胚胎发育的分子模拟，每个新成分的形成和定位不断改变整体。该假设的推论与翻译和遗传密码的进化有关。凭借通道作用，生物合成相关的氨基酸（例如天冬氨酸和苏氨酸）会在复合物中紧密结合在一起出现。第二个前提是，具有相似碱基序列和相似反密码子的 tRNA 也在复合物中聚集在一起，并引导到相邻位点。由于这些综合作用，具有相似反密码子的 tRNA 必然位于靠近代谢相关氨基酸的位置，因此更有可能带有代谢相关氨基酸。这种机制为观察到的遗传密码的密码子结构提供了新的原理，其中生物合成相关的氨基酸具有相似的密码子。 (C) 1996 学术出版社有限公司
A central question in the origin of life concerns whether primitive metabolites and catalysts interacted randomly in solution, as often envisaged, or whether they were arranged from the start in ordered metabolic complexes. The latter possibility would be consistent with the hypothesis of metabolite channeling in extant cells, which holds that intermediates in many pathways are transferred directly, without diffusion, between pathway enzymes. A model on this basis is proposed in which life originated autotrophically de novo in metabolic complexes organized on FeS2 (pyrite) mineral surfaces. Because metabolites and catalysts arose at specific sites in these complexes, they could interact specifically with neighbouring species in evolving pathways prior to the existence of protein enzymes with precise substrate binding sites. In successive stages, RNA catalysts and protein enzymes could be incorporated in these arrays. The overall process may be viewed as a molecular analogue of embryonic development, with the formation and positioning of each new component continuously transforming the whole.A corollary of the hypothesis relates to the evolution of translation and the genetic code. By virtue of channeling, biosynthetically related amino acids (e.g., aspartic acid and threonine) would have arisen close together in the complex. A second premise is that tRNAs with similar base sequences, and thus similar anticodons, were also clustered together in the complex and channeled to adjacent sites. As a result of these combined effects, tRNAs with similar anticodons would necessarily have been positioned close to, and thus more likely to have been charged with, metabolically related amino acids. This mechanism affords a new rationale for the observed codon structure of the genetic code, in which biosynthetically related amino acids possess similar codons. (C) 1996 Academic Press Limited