Wellcome Trust Sanger Institute, Hinxton, Cambridge, UK.
Department of Biochemistry and Cambridge Systems Biology Centre, University of Cambridge, Hinxton, UK.
Sci Rep. 2017 Jun 9;7(1):3141. doi: 10.1038/s41598-017-02799-6.
The origin-of-life problem has been traditionally conceived as the chemical challenge to find the type of molecule and free-solution reaction dynamics that could have started Darwinian evolution. Different autocatalytic and 'self-replicative' molecular species have been extensively investigated, together with plausible synthetic pathways that might have led, abiotically, to such a minimalist scenario. However, in addition to molecular kinetics or molecular evolutionary dynamics, other physical and chemical constraints (like compartmentalization, differential diffusion, selective transport, osmotic forces, energetic couplings) could have been crucial for the cohesion, functional integration, and intrinsic stability/robustness of intermediate systems between chemistry and biology. These less acknowledged mechanisms of interaction and molecular control might have made the initial pathways to prebiotic systems evolution more intricate, but were surely essential for sustaining far-from-equilibrium chemical dynamics, given their functional relevance in all modern cells. Here we explore a protocellular scenario in which some of those additional constraints/mechanisms are addressed, demonstrating their 'system-level' implications. In particular, an experimental study on the permeability of prebiotic vesicle membranes composed of binary lipid mixtures allows us to construct a semi-empirical model where protocells are able to reproduce and undergo an evolutionary process based on their coupling with an internal chemistry that supports lipid synthesis.
生命起源问题一直被传统地视为化学挑战，旨在寻找能够引发达尔文式进化的分子类型和自由溶液反应动力学。已经广泛研究了不同的自催化和“自我复制”分子物种，以及可能导致这种最简情景的合理合成途径。然而，除了分子动力学或分子进化动力学之外，其他物理和化学约束条件（如隔室化、差异扩散、选择性运输、渗透压、能量偶联）对于化学和生物学之间的中间系统的凝聚、功能集成和内在稳定性/鲁棒性可能至关重要。这些不太被认可的相互作用和分子控制机制可能使前生物系统进化的初始途径更加复杂，但鉴于它们在所有现代细胞中的功能相关性，对于维持远离平衡的化学动力学肯定是必不可少的。在这里，我们探索了一种原细胞情景，其中考虑了一些这些额外的约束/机制，并展示了它们的“系统级”影响。特别是，对由二元脂质混合物组成的前生物囊泡膜的渗透性的实验研究使我们能够构建一个半经验模型，其中原细胞能够基于与支持脂质合成的内部化学的耦合来进行复制和经历进化过程。
