Exploring life with ease: Scientists create a 'minimalist cell membrane' with just two lipids

A research team from the B CUBE-Center for Molecular Bioengineering at the TUD Dresden University of Technology has shown that cells can function with just two lipids. They have created a cell with a minimal, adaptive membrane, offering a unique platform to study how lipid complexity has evolved and how it can be engineered for artificial life. Their results are published in Nature Communications.

Membranes are like bubbles that enclose cells and separate them from their surroundings. Membranes also serve as platforms where molecules interact, coordinating processes essential for life.

“There is a huge diversity of lipids in nature, and almost every organism has its own set of lipids, known as the lipidome. Human cells, for example, employ hundreds of different types of lipids,” says Dr. James Senz, research team leader at B CUBE who led the study.

 "Yet, these different mixtures of lipids all provide solutions to the same fundamental evolutionary challenges: creating a stable barrier and organizing organic molecules in space and time. We want to understand why so many different lipids have evolved, why life is needed, and how they can be used to engineer synthetic living systems."

Testing the limits of the lipidome :-

For their study, the group started with Mycoplasma mycoides, a naturally occurring pathogenic bacterium. Unlike most cells, Mycoplasma cannot produce its own lipids and must instead use lipids provided by its host. By systematically supplementing the cells with different lipid compositions, the researchers narrowed down the composition required for survival and division.

They found that cells can survive on a "diet" of just two lipids: cholesterol and another so-called bilayer-forming lipid, phosphatidylcholine.

"These two lipids alone are not the only ones that can support life," says Isaac Justice, a Ph.D. student who completed the project. "But having a bilayer-forming lipid, which provides the basic structure for the cell membrane, and a non-bilayer-forming lipid, such as cholesterol, which adds stability, seems to be a fundamental requirement."

Surprising effects of the two-lipid diet

The team observed cells on a minimal lipid diet under an electron microscope and saw dramatic effects on cell size and shape. Some cells grew ten times their normal size, while others developed unusual shapes and distortions.

 “What surprised me most was that about half of the cells with just two lipids were completely normal. They were round and well-divided. Despite the drastic reduction in lipid complexity, they continued to function surprisingly well,” Justice said.

The challenge of reducing complexity: 

Achieving this minimal lipid composition was no easy task. Initial experiments showed that mycoplasmas could modify most of the lipids they were fed, transforming them into new types.

“When we provided cholesterol and a common bilayer phospholipid, the cells were able to make about 30 different lipids from them,” explains Dr. Senz. To control the minimal lipid composition, the team provided cells with very similar lipids but linked by a different type of chemical bond that the cells were unable to break with their enzymes.

 Reverse engineering the complexity of life:-

After identifying the minimal lipid diet, researchers applied it to a “minimal cell” called JVCI-Syn3A, which was engineered at the J. Craig Venter Institute to contain only the genes needed for survival. Now, with both a minimal genome and lipidome, this cell provides a powerful new tool for synthetic biology.

Writer :- Dip Sarker 

(Scipen World Team)