Piercing Mechanism of Biological Nano-injection Machines

Mechanical injection, a process of material delivery into living cells using a needle, is a fundamental technique for a variety of applications in biology and medicine including single-cell transfection and drug delivery. To generate genetically modified cells with desired functions, developing an efficient injection technique capable of precise delivery of genomes into host cells without any damage to intracellular organelles is required. Designing such an efficient injection device can be inspired from biological injection machines including contractile bacteriophages. Contractile phages are remarkable nano-scale injection machines that kill competing bacteria by rupturing cell membrane and injecting their genome into the host. Since the structure and function of phages have been honed to perfection by millions of years of evolution, any engineered injection system mimicking the injection mechanism of bacteriophages is likely to be successful. A key step is to understand the structure and function of the bacteriophages. We propose a dynamic model of contractile phages to elucidate how they work in real-time. The model reveals the predictions of the dynamics, energetics, and mechanism of the injection machine and common physical principles underlying their injection process.