Manipulation of the motility of protein molecular motors on microfabricated substrates

Heavy meromyosin (HMM), a proteolytically cleaved derivative of myosin has previously been shown to interact with actin in well-established in vitro motility assays on nitrocellulose surfaces. In this study, the assays were conducted to demonstrate that the motility of actin filaments is confined in the micron-sized channels fabricated via laser ablation in a layer of the photosensitive resist polymer O-acryloyloxime acetophenone oxime (AAPO). A solution containing myosin labeled with fluorophore 5-iocloacetamiclofluorescein (5-IAF) was applied to the microfabricated AAPO surface and shown to bind specifically to the micron-size channels. In the motility assay, HMM, rhodamine-phalloidin labeled actin and ATP were sequentially added and the movement of the actin filaments was observed by fluorescence microscopy and recorded with a CCD camera. The experiments prove that although the actin filaments show an only-partial propensity for attachment in myosin-rich areas, their motility is confined to a large extent in micro-channels.