Evrim Yazgin
Cosmos science journalist
A reaction between 2 simple molecules might be the secret to uncovering how the building blocks of life were first encapsulated in a cell membrane, according to new research.
There are a few ingredients needed for life on Earth. Most obviously, there’s the genetic material which governs the production of proteins and reproduction. That is DNA and RNA. But there’s another, less discussed ingredient: lipids.
Lipid membranes are the long chains of fatty acids that house the interior of cells and act as a scaffold for many biological reactions.
How lipids came to form membranes of protocells which would develop into the first single-celled organisms billions of years ago been one of the unsolved mysteries about the emergence of life on our planet.
New research published in Nature Chemistry might provide the answer to this question.
Short fatty chains containing fewer than 10 carbon-carbon bonds were probably abundant on early Earth. But complex fatty chains have nearly twice as many – these longer chains are required to form vesicles, the compartments that house the cell’s machinery.
Such chains can be formed in the presence of enzymes.
“But over four billion years ago, there were no enzymes,” says senior author Neal Devaraj from the University of California San Diego. “Yet somehow these first protocell structures were formed. How? That’s the question we were trying to answer.”
Devaraj’s team started with 2 simple molecules: an amino acid named cysteine and a short-chain choline thioester, similar to molecules involved in the biochemical formation and degradation of fatty acids.
They used silica glass as a mineral catalyst. On the glass surface, the cysteine and thioesters spontaneously reacted to form lipids, generating protocell-like membrane vesicles stable enough to sustain biochemical reactions.
“Part of the work we’re doing is trying to understand how life can emerge in the absence of life. How did that matter-to-life transition initially occur?” Devaraj says. “Here we have provided one possible explanation of what could have happened.”
