Engineers developing artificial cells need a way to generate force on command for movement, shape change and division. Biological cells usually use ATP to power motor proteins, but some ciliates use a calcium pulse for ultra-fast contraction and then ATP to pump calcium back.
In a Nature Communications study led by Georgia Tech, researchers produced and purified Tetrahymena thermophila calcium-binding protein 2 (Tcb2). In the lab the protein forms a fibrous network that contracts when calcium is released. The team controlled calcium release with a light-sensitive chelator, often called a "cage," and projected light patterns so the network assembled and contracted in matching shapes.
With pulsed illumination the network repeated contraction cycles and could move microscopic particles. The team also built computer models and used simulations with reinforcement learning to design light patterns that push or pull the network. The study was funded in part by the National Science Foundation.
Difficult words
- generate — produce power, energy, or movement
- contract — become smaller or tighter in response to a signalcontracts
- chelator — molecule that binds metal ions tightly
- reinforcement learning — computer method that learns from feedback
- illumination — light shining on an object or area
- calcium — a chemical element essential for living cells
Tip: hover, focus or tap highlighted words in the article to see quick definitions while you read or listen.
Discussion questions
- How could light-controlled contracting protein networks be useful in tiny machines or medical devices?
- Would you prefer artificial cells that use ATP or calcium pulses for movement? Why?
- What challenges might scientists face when using light patterns to move microscopic particles?
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