Evolution of Proliferative Model Protocells Highly Responsive to the Environment

Abstract

In this review, we discuss various methods of reproducing life dynamics using a constructive approach. An increase in the structural complexity of a model protocell is accompanied by an increase in the stage of reproduction of a compartment (giant vesicle; GV) from simple reproduction to linked reproduction with the replication of information molecules (DNA), and eventually to recursive proliferation of a model protocell. An encounter between a plural protic catalyst (C) and DNA within a GV membrane containing a plural cationic lipid (V) spontaneously forms a supramolecular catalyst (C@DNA) that catalyzes the production of cationic membrane lipid V. The local formation of V causes budding deformation of the GV and equivolume divisions. The length of the DNA strand influences the frequency of proliferation, associated with the emergence of a primitive information flow that induces phenotypic plasticity in response to environmental conditions. A predominant protocell appears from the competitive proliferation of protocells containing DNA with different strand lengths, leading to an evolvable model protocell. Recently, peptides of amino acid thioesters have been used to construct peptide droplets through liquid–liquid phase separation. These droplets grew, owing to the supply of nutrients, and were divided repeatedly under a physical stimulus. This proposed chemical system demonstrates a new perspective of the origins of membraneless protocells, i.e., the “droplet world” hypothesis. Proliferative model protocells can be regarded as autonomous supramolecular machines. This concept of this review may open new horizons of “evolution” for intelligent supramolecular machines and robotics.

Membranous and Membraneless Interfaces—Origins of Artificial Cellular Complexity

“…Sugawara and collaborators [27] reviewed the fascinating combination of nucleic acids, membranes, and membrane catalysts (in a model protocell) aiming at generating wholeprotocell self-reproduction (in this specific case, the protocell is a DNA-containing vesicle made of special kinds of surfactants). The central point of the discussion refers to the local organization of a supramolecular catalyst which enables the membrane's growth, followed by division (overall, the process corresponds to self-reproduction).…”

Chemotactic Interactions Drive Migration of Membraneless Active Droplets

“…Due to its fundamental role, current intracellular pathways leading to cellular chemotaxis have been deeply studied, , but mimicking in vitro the cellular degree of complexity is challenging. In fact, how nature has achieved this level of complexity is not completely understood. , Studying how these cellular functions work and arise requires life-like systems capable of mimicking cellular complex features, such as tangled metabolic networks, cytosolic macromolecular crowding, proliferation, and migration. − Thus, reproducing pivotal chemotactic interactions is a key step to unraveling the basic natural rules driving collective behavior and the physical principles ruling these phenomena.…”

Chemotactic interactions drive migration of membraneless active droplets

“…In fact, how nature has achieved this level of complexity is not completely understood [13,14]. Studying how these cellular functions work and arise require life-like systems capable of mimicking cellular complex features, such as metabolic density, cytosolic macromolecular crowding, proliferation and migration [15][16][17]. Thus, reproducing pivotal chemotactic interactions is a key step to unravel basic natural rules driving collective behavior and the physical principles ruling these phenomena.…”