How primitive cell membranes may have been formed
doi:10.1038/nindia.2020.47 Published online 16 March 2020
Biologists from the Indian Institute of Science Education and Research (IISER) in Pune have shed new light on how the membranes of primitive cells formed1.
They have shown that stable mixed-membrane systems flourished under diverse environmental conditions on early Earth.The scientists say that such membranes would have been suitable for supporting primitive life forms.
The IISER researchers, led by Sudha Rajamani, created different membrane systems using various fatty acids and their derivatives containing alcohol and glycerol. They then explored the ability of the membrane systems to form vesicles, or membrane-wrapped structures, in neutral and alkaline media at room temperature and in the presence of magnesium ions.
Mixed membrane systems, made of two types of fatty acids, formed vesicles over a wide range of pH levels. Adding alcohol and glycerol derivatives to the mixed system enhanced the vesicle-forming capacity of the membranes at different pH levels. But, pure fatty acid membrane, made of oleic acid, formed vesicles only from pH 8 to 9.
Permeability is an essential property that allows the transport of polar molecules through cellular membranes. The mixed membranes displayed better permeability than the pure fatty acid membrane.
The mixed membrane system was also stable when exposed to low concentrations of free magnesium ions. Separate studies have shown that a similar membrane system could enclose and facilitate the function of ribozyme, an enzyme and self-replicating RNA molecule.
Under simulated conditions that probably existed on early Earth, the mixed membrane showed a better chance of survival, making it a likely candidate to have paved the origin of primitive life forms.
1. Sarkar, S. et al. Compositional heterogeneity confers selective advantage to model protocellular membranes during the origins of cellular life. Sci. Rep. 10, 4483 (2020)