title: Myosin V is a biological Brownian machine.
abstract: Myosin V is a vesicle transporter that unidirectionally walks along cytoskeletal actin filaments by converting the chemical energy of ATP into mechanical work. Recently, it was found that myosin V force generation is a composition of two processes: a lever-arm swing, which involves a conformational change in the myosin molecule, and a Brownian search-and-catch, which involves a diffusive "search" by the motor domain that is followed by an asymmetric "catch" in the forward actin target such that Brownian motion is rectified. Here we developed a system that combines optical tweezers with DNA nano-material to show that the Brownian search-and-catch mechanism is the energetically dominant process at near stall force, providing 13 kBT of work compared to just 3 kBT by the lever-arm swing. Our result significantly reconsiders the lever-arm swinging model, which assumes the swing dominantly produces work (>10 kBT), and sheds light on the Brownian search-and-catch as a driving process.
authors: Quantitative Biology Center, RIKEN, Suita, Osaka 565-0874, Japan.
authors: Keisuke
authors: K
authors: Fujita
authors: Quantitative Biology Center, RIKEN, Suita, Osaka 565-0874, Japan; Graduate School of Frontier Biosciences, Osaka University, Suita, Osaka 565-0871, Japan.
authors: Mitsuhiro
authors: M
authors: Iwaki
keywords: Brownian motor; motor protein; myosin; nano machine