Magnetic control of bacterial magnetite-myosin conjugate movement on actin cables

The control of actin-myosin movement using a bacterial magnetic particle (BMP) which was synthesized intracellularly by magnetic bacteria was investigated. Myosin immobilized on the BMP ( myosin-BMP conjugate) was prepared with heterobifunctional reagents, Sulfo-LC-SPDP (sulfosuccinimidyl 6-(3′-(2-pyridyldithio)-propionamido)hexanoate) and Sulfo-SMCC (sulfosuccinimidyl 4-(N-maleimidomethyl)cyclohexane-1-carboxylate). When a magnetic force was applied in the same direction as the myosin-BMP conjugate movement (negative magnetic force) at 22–23°C, the velocity increased from 2.0 μm s−1 to 7.5 μm s−1. When a magnetic force was applied in the opposite direction to the myosin-BMP conjugate movement ( positive magnetic force ), the velocity decreased from 10.7 μ s−1 to 0 μm s−1. These results indicate that the sliding force of the myosin-BMP conjugate caused by the actin-myosin interaction can be controlled using a neodymium-boron (Nd-B) magnet. It will be possible to develop a nano-sized actuator that can be controlled by the external magnetic force. This system could also be applicable to analysis of the dynamics of a single myosin molecule.