A new study on the origin of life has found that short, positively charged hydrophobic peptide inducing electrostatic interactions were all it took to attach RNA structures to vesicle membranes. This new discovery comes to provide new insight into how membranes and RNA could have come together to form the precursors to life called protocells. This process was taking place around 4 billion years ago on Earth.
Scientists assume that RNA is the ancestral nucleic acid found in early cells. RNA can catalyze chemical reaction as well as store genetic information. Scientists also consider membranes an important piece in the puzzle. They are thought to have played an important role in prebiotic chemistry by promoting a variety of processes, trapping nucleic acids inside vesicles and co-localizing reactants on their surface.
The physical association of vesicle membranes and RNA may have been a significant event in early cellular evolution. Determining pre-biotically possible ways through which membranes and RNA and can associate is an important aspect of understanding the formation process of early cells.
A team at the Massachusetts General Hospital in Boston, U.S., including Nobel laureate Jack Szostak found that peptides just seven amino acids long or even fewer are able to localize RNA to a basic cell membrane.
According to the first author of the research paper, Neha Kamat, this is a simple mechanism that has been also used in other fields to form RNA complexes from a variety of materials. She explains that the simplicity of their system makes this mode of RNA-membrane association plausible on our primitive Earth.
The authors of the study used small peptides containing a cationic group interacting electrostatically with phosphate groups of RNA negatively charged, and a hydrophobic group associating with the membrane.
Kamat explains that this kind of peptides may have helped to bring membranes and RNA together since they could have been present on the prebiotic Earth. According to the scientist, the peptides essentially act as a kind of glue that first binds membranes and then hold the RNA at the membrane surface.
The conclusion of the study is that the first forms of life were likely to be simple cells made of peptides and short strands of a nucleic acid such as RNA, explains David Deamer, chemist specialized in membrane evolution at the University of California, Santa Cruz.