Engineering Myosin V Velocity by Tuning Nanocomposite Morphology

Abstract

Devices which utilize biological components such as molecular motors may be capable of detecting or separating analytes with speed and resolution rivaling macroscopic instruments. The design and manufacturing of such devices requires detailed understanding of self-assembly and interactions of biological materials with synthetic environments. We demonstrated that nano-scale roughness modulates surface binding of F-actin (Langmuir 28:12216; 2012). By controllably converting a thin film of polystyrene-random-tert butyl acrylate copolymer to polyacrylic acid (PAA), we grafted amine-functionalized nanoparticles at high coverage to the PAA hydrogel, creating a surface with tunable roughness. Extending that approach here, we explore the effect of nanocomposite morphology on myosin V processive motility. We find that tuning the size and density of the surface grafted nanoparticles controls the velocity and run length of myosin V. Velocity decreases significantly as the nanoparticle size is increased independent of the concentration of MgATP. This effect of particle size may be due to changes in net charge, nanoparticle curvature at the interaction sites, or tortuosity of the actin imposed by the surface features. Experiments to distinguish these hypotheses are underway. Further understanding of the relationship between nanoparticle surface morphology and activity of actin in support of motility may permit the engineering of stops or stalls with high spacial precision into biomolecular devices. Supported by NSF/NSEC grant DMR08-32802.