Scientists reveal how the first cells on Earth may have evolved

Any hypothesis concerning the origin of life must include the prebiotic genesis of protocells. Although phospholipid vesicles are well studied, how fatty acid-based vesicles emerged is still to be determined.

A recent Scripps study offers a possible explanation for how protocells evolved early and then evolved chemically to carry out various tasks.

According to the study, PhosphorylationA chemical process by which a molecule acquires phosphate groups—may have appeared sooner. The result is highly structurally complex, double-chain protocols with a wide range of functions that support chemical reactions and dissociation. Scientists can better understand how early evolution occurred by uncovering the process by which protocells formed.

The study could provide a better understanding of the early Earth's chemical environments, which could help determine the origins of life and how life evolved on the early Earth.

In this study, scientists looked at the chemical processes that formed essential materials and structures on the early Earth before life began to evolve. They explored the possibility that phosphates have a role in the protocell developmental process. Since phosphates are involved in almost all body chemical reactions, Krishnamurti speculated that their existence may be much older than previously thought.

Previously, scientists thought that fatty acids formed protocells; However, how protocells switched from single-chain to double-chain phosphate was unclear.

To determine, the scientists wanted to replicate plausible prebiotic conditions. They started by identifying three chemical compounds that could form vesicles, spherical structures of vesicles similar to protocells.

Fatty acids and glycerol, a common soap-making by-product that may have existed in Earth's early history, were among the compounds used. They added other chemicals to create new compounds while seeing how these compounds behaved. These solutions were repeatedly heated and cooled throughout the overnight shaking to promote chemical reactions.

They then examined the mixtures using fluorescent dyes to see if vesicle formation had occurred. The scientists periodically varied the pH and component ratios to learn more about how these variables affected vesicle formation. They also studied how temperature and metal ions affect the stability of the vesicles.

First author Sunil Pulletikurthy, a postdoctoral researcher in Krishnamurthy's lab, said, „During our experiments the vesicles were able to switch from a fatty acid environment to a phospholipid environment, suggesting that a similar chemical environment may have existed 4 billion years ago.”

A more stable double-chain structure may be formed by phosphorylation of fatty acids and glycerol. In particular, glycerol-derived fatty acid esters may have formed vesicles with differential sensitivity to pH, temperature, and metal ions—an important step in the evolution of diversification.

Denise said, „It's exciting to discover how early chemistry may have changed to allow life on Earth. Our findings also point to a wealth of intriguing physics that may have played key functional roles for modern cells.

Journal Note:

1. Sunil Bulletikurthy et al. We experimentally model the origin of prebiotically plausible phospholipid vesicles. Chem. DOI: 10.1016/j.chempr.2024.02.007