<p>The
prelude to the origin of cellular life on Earth would have involved a fundamental
step, that of protocell formation. This involves the coming together of two
crucial processes; abiotic synthesis of informational and catalytic polymers,
and the assembly of membrane compartments. Mutual interactions between these
processes would have likely affected the emergence and early stages of
protocell evolution. Previous investigations have predominantly focused on
cooperative interactions, often neglecting any competitive behavior that might
ensue as ‘counterproductive cross-talk’. However, in a realistic scenario, both
cooperative and competitive reactions would have occurred simultaneously in a
complex prebiotic soup, generating a plethora of
chemical species with their own prebiotic implications. In this study, we followed
a systematic and unbiased approach to explore this interdependence. We
used a lipid-amino acid system to demonstrate the above-mentioned phenomenon
wherein we investigated the effect of a membrane-forming amphiphile on peptide
synthesis, under prebiotically plausible conditions. </p><p><br></p>
<p>Interestingly, our study shows the formation of a hitherto unobserved reaction
product that could have played a significant role during the emergence of life
on the early Earth. We do show that peptide synthesis occurs but with a
decrease in the yield. This is due to another concurrent and competing
reaction, wherein an amino acid covalently interacts with a phospholipid to
generate new amphiphilic species called N-acyl amino acids (NAAs) via an
ester-amide exchange process. These NAAs are thermostable and, hence, persistent
even at high temperatures. Furthermore, this protoamphiphile is also able to
self-assemble into vesicles at acidic pH. <i>Au
contraire</i>, fatty acids, a widely accepted constituent of prebiotic
compartments, have been shown to generate vesicles only at neutral to alkaline
pH. Thus, NAAs could have had a selective advantage over fatty acids to form
thermostable protocell compartments under acidic geothermal pool-like
conditions, a niche that has gained prominence as one of the important
geological settings where life could have originated. Our study underlines the
importance of an unbiased exploration of the complex interactions between
prebiotic processes, which could potentially open new avenues to solving the
origin of life conundrum. </p>
<p> </p>