Schematic of engineered artificial organelles inside a proteinosome.

An artificial protocell with a protein skin (blue) holds self-contained liquid droplets that function like cellular organelles. Credit: Yan Qiao

Synthetic biology

Complex, lab-made ‘cells’ react to change like the real thing

Synthetic structures that grow artificial ‘organelles’ could provide insights into the operation of living cells.

Artificial sacs made of proteins and stuffed with tiny liquid droplets resembling cellular substructures can respond to changes in their environment, not unlike living cells.

The simple models of living cells called protocells can help researchers to probe how the real thing processes information. Yan Qiao at the Chinese Academy of Sciences in Beijing, Yiyang Lin at Beijing University of Chemical Technology and their colleagues devised a protocell comprising a protein sac packed with internal ‘organelles’ made from a mixture of short, light-sensitive molecules and long, pH-sensitive polymers.

The organelles form at certain light and pH levels that prompt the components to intertwine into liquid spheres, which are well defined despite lacking membranes. Enzymes or strands of DNA can become concentrated inside the developing organelles, mimicking the build-up of such biomolecules inside cells.

The protocells can process binary signals: organelles form if protocells are exposed to either lactose or oxygen, or to neither. But together, lactose and oxygen inhibit formation of organelles, and cause existing ones to unravel. This information-processing ability could allow scientists to program the protocells as if they were computer chips, to control chemical reactions.