Cellular compartments are membrane-enclosed, spatially distinct microenvironments which confine and protect biochemical reactions in the biological cell. On the early Earth, the autonomous formation of compartments is thought to have led to the encapsulation of nucleotides, thereby satisfying a starting condition for the emergence of life. Recently, surfaces have come into focus as potential platforms for the self-assembly of prebiotic compartments, as significantly enhanced vesicle formation was reported in the presence of solid interfaces. The detailed mechanism of such formation at the mesoscale is still under discussion. We report here on the spontaneous transformation of solid surface-adhered lipid deposits to unilamellar membrane compartments through a straightforward sequence of topological changes, proceeding via a network of interconnected lipid nanotubes. We show that this transformation is entirely driven by surface-free energy minimization and does not require hydrolysis of organic molecules, or external stimuli such as electrical currents or mechanical agitation. The vesicular structures take up and encapsulate their external environment during formation, and can subsequently separate and migrate upon exposure to hydrodynamic flow. This may link, for the first time, the self-directed transition from weakly organized bioamphiphile assemblies on solid surfaces to protocells with secluded internal contents. protocell | biomembrane | lipid nanotube | origin of life SignificanceThe nature of the physical and chemical mechanisms behind the formation, growth and division of the earliest protocells is among the key questions concerning the origin of life. Establishing a simple pathway for the assembly of protocell structures from the primordial soup is a particular challenge. Emerging evidence supporting the assumption that solid surfaces have a governing role in protocell formation has recently expanded the scope, and created new inspiration for investigation. By presenting a physical path from self-assembled amphiphile-based membranes on solid surfaces to spherical single-membrane compartments via a consistent sequence of transformations, solely driven by the materials properties of the interfaces, a direct link between the presence of functional biomolecules and the development of protocells can be established.

Membrane enclosed intracellular compartments have been exclusively associated with the eukaryotes, represented by the highly compartmentalized last eukaryotic common ancestor. Recent evidence showing the presence of membranous compartments with specific functions in archaea and bacteria makes it conceivable that the last universal common ancestor and its hypothetical precursor, the protocell, may have exhibited compartmentalization. To the authors’ knowledge, there are no experimental studies yet that have tested this hypothesis. They report on an autonomous subcompartmentalization mechanism for protocells which results in the transformation of initial subcompartments to daughter protocells. The process is solely determined by the fundamental materials properties and interfacial events, and does not require biological machinery or chemical energy supply. In the light of the authors’ findings, it is proposed that similar events may have taken place under early Earth conditions, leading to the development of compartmentalized cells and potentially, primitive division.

to assemble astonishing pieces of a complicated puzzle, and realized that further advancement requires input from multiple branches of science, not just biology as the primary life science. Detailed hypotheses have been established about the different scenarios of the emergence of life, including the "RNA world," [1] the "lipid world," [2] "replicator first," [3] "metabolism first," [4][5][6] and others. Although the origin of life is still surrounded by many open questions, our understanding of chemical, physicochemical, and biochemical processes possibly involved in the ancient events preceding Darwinian evolution has seen much progress. We have come a long way from Leduc's physicochemical, inorganic matter-centered view on the beginning of the evolution, yet the matter of the transition from nonliving to living matter still remains largely unsolved, and one of the great scientific problems of our time.The phylogenetic tree of different living domains reflects that life has evolved from simple to more complex structures, i.e., from single-to multicellular organisms. The oldest fossil evidence dating back 3.5 Gy (billion years) comes from stromatolites, [7][8][9][10] microorganismal residues in sedimentary rocks. [11] There appears to be a gap of knowledge regarding the period of evolution between the first primitive hypothetical cells and the fossilized ancient bacteria, which can be considered as an already advanced form of life. [12] It is highly likely that intermediate primitive cell precursors preceded the single-cell organisms. The hypothetical prebiotic structures that were the stepping stone to first self-sustaining living cells are commonly termed "protocells." The possibility of a strong link between the formation of protocells and the origin of life can today be reasonably assumed.One cannot easily proceed in the context of the evolution of cell-based organisms without briefly illuminating the concept of life as we know it on our planet. Over time, different requirements have been proposed for an entity to be considered alive. According to Tibor Ganti's chemoton model, [13] a protocell contains three autocatalytic subsystems: a membrane subsystem that keeps the components together and intact, a metabolic subsystem that captures energy and material resources, and an information subsystem that processes and transfers heritable information to progeny. To be considered alive, these subsystems must be unified and function co-operatively for the survival and evolution of the supersystem. Pohorille and Deamer suggested a modified set of 7 criteria related to the chemoton. [14] At about the same time, Oro defined the requirements by 10 characteristic features. [15] Despite their differences, these descriptions align well with NASA's broader definition of life: "a self-sustaining chemical system capable of Darwinian evolution."The origin of life is still one of humankind's great mysteries. At the transition between nonliving and living matter, protocells, initially featureless aggregates of abiotic matter, ga...

Elevated temperatures might have promoted the nucleation, growth, and replication of protocells on the early Earth. Recent reports have shown evidence that moderately high temperatures not only permit protocell assembly at the origin of life, but can have actively supported it. Here, the fast nucleation and growth of vesicular compartments from autonomously formed lipid networks on solid surfaces, induced by a moderate increase in temperature, are shown. Branches of the networks, initially consisting of self‐assembled interconnected nanotubes, rapidly swell into microcompartments which can spontaneously encapsulate RNA fragments. The increase in temperature further causes fusion of adjacent network‐connected compartments, resulting in the redistribution of the RNA. The experimental observations and the mathematical model indicate that the presence of nanotubular interconnections between protocells facilitates the fusion process.

The experimental observations revealed that the interaction of styrene maleic acid with lipid membranes results in formation of toroidal pores.