Kai Liu, Ph.D.

Postdoctoral Research Fellow, Rijksuniversiteit Groningen

Education: Chinese Academy of Sciences, Ph.D., Biochemical Engineering
Institution: Rijksuniversiteit Groningen (laboratory of Sijbren Otto)

SCOL Project: Photometabolic Self-Replication

The origin of life remains one of the most fascinating and challenging problems for science. All living beings are mainly composed of water and organic molecules, and chemistry undoubtedly becomes a promising approach to shed new light on the puzzle. How does nonliving matter get translated into an “alive” state? It is known from experience that living things can grow and reproduce in a certain condition corresponding to three key properties of life: metabolism, replication and compartmentation. Given the lack of historic records, it is difficult for scientists to uncover the exact synthetic itinerary that led to the above properties. But regardless of the exact itinerary, it is clear that each property is based on complex molecular networks and that the individual subsystems have been become intimately integrated in the course of evolution. It is becoming increasingly apparent that a systems chemistry approach, focusing on networks of reactions and organization, will open new vistas in origin-of-life research.

Herein, we will design a complex chemical system capable of utilization of light energy for its own reproduction, akin to photosynthetic organisms, based on the unique expertise of the host lab (self-replicating molecules) combined with the strong expertise of the experienced researcher (self-assembly and photochemistry). This combination will enable the adaptive integration of photoactive porphyrins (similar to chlorophyll in photosynthesis) to the replicator fiber and activate their photocatalytic activity in single oxygen production. The generated single oxygen can accelerate the oxygen of raw material (i.e., thiol building blocks) into “food” (i.e., small disulfide macrocycles), which the replicator can utilize to make copies of itself. The above system can be regarded as a primary model integrating metabolism and replication. In addition, we will operate the system in an open flow system, in which the “self-grow” of replicator (i.e., replication using the matter and energy in the surrounding environment) competes with “death” (i.e., physical removal), resulting in a dynamic, kinetic-stable state of replicators, a special feature of living matter. This regime should allow for Darwinian evolution, an important living phenomenon, provided that replicator mutation is facilitated by providing different building blocks. In order to survive, replicators need to reproduce faster than being destroyed. Therefore, selection should favor the replicator with the highest activity to maintain itself. Overall, the systems will exhibit all aspects of Darwinian evolution: replication, mutation and selection. Our results are expected to provide valuable new insights into possible scenarios for the origin of life from the perspective of systems chemistry: a possible origin of biological organization, the interplay of metabolism and replication, the transition from inanimate to animate matter and the onset of Darwinian evolution.

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