Light-Controlled Molecular Shuttles Made from Motor Proteins Carrying Cargo on Engineered Surfaces

Abstract

Molecular shuttles have been built from motor proteins capable of moving cargo along engineered paths. We illustrate alternative methods of controlling the direction of motion of microtubules on engineered kinesin tracks, how to load cargo covalently to microtubules, and how to exploit UV-induced release of caged ATP combined with enzymatic ATP degradation by hexokinase to turn the shuttles on and off sequentially. These are the first steps in the development of a tool kit to utilize molecular motors for the construction of nanoscale assembly lines.One of the central challenges in nanotechnology is how to assemble nanoscale building blocks including molecular wires and nanoscale switches into addressable devices, where the building blocks can be either synthesized, self-assembled in solution, or fabricated at the nanoscale. Ideally, a nanoscale conveyor belt would allow us to transport a selected nanoscale item over a defined distance and then facilitate the docking under defined angles with a second item of choice. One labor-intensive approach is to use tips of scanning probe microscopes to pick up, move, and release atoms, single molecules, and nanoscale objects in a controlled manner, one at a time. 1 Nanoscale objects created in this way are therefore pieces of art rather than devices of economical value. Methods need to be developed that allow the parallel assembly of nanoscale building blocks in large numbers. Here we combine methods of micro-and nanofabrication, with molecular assembly, and molecular motors powered chemically by adenosine triphosphate (ATP) to construct molecular shuttles that move under user control. This represents the first step in learning how to construct and operate nanoscale conveyor belts in large numbers.Key features of conveyor belts are that they (a) are driven by a force-generating motor, (b) transport cargo unidirectionally between well-defined positions, (c) accommodate loading and docking of cargo, and (d) can be externally switched on and off. These features are independent of the length scale at which conveyor belts are constructed and operated. If operation at the nanoscale is desired, molecular motors are required to generate force to propel cargo. Furthermore, schemes have to be developed to guide molecular movement along precisely controlled tracks, to load and unload cargo, and to control the speed of motion noninvasively. We will review and describe novel approaches that can serve as universal elements of a tool kit to construct and operate molecular shuttles. Molecular Motors. Nature has evolved unique molecules, termed motor proteins, that transport cargo over long distances or rotate loads in an energy-dependent manner. The characteristics of these motor proteins are far superior to all demonstrated miniaturized synthetic engines. 2 Motor proteins generate more force, have better fuel efficiency, and are smaller in size than any man-made device.

Parallel computation with molecular-motor-propelled agents in nanofabricated networks

“…Both kinds of cytoskeletal filaments have small diameters (∼10 nm for actin filaments and ∼25 nm for microtubules) and move at high speeds (5-10 μm s −1 for actin filaments driven by fast myosin II from skeletal muscle, and ∼0.5-1 μm s −1 for microtubules driven by kinesin-1). The filaments are guided unidirectionally (23, 24) along lithographically defined channels, which are functionalized with molecular motors, and whose roofs are open to supply the motors with biochemical fuel (adenosine 5′-triphosphate, ATP) by diffusion from the surrounding buffer fluid (25,26), allowing for a distributed energy supply. The width of the channels was set to below 200 nm and 250 nm, for actin filaments and microtubules, respectively, which were observed to reliably guide cytoskeletal filaments (27)(28)(29).…”

Microtubule shuttles on kinesin-coated glass micro-wire tracks

“…Namely, in order to apply gliding microtubules driven by molecular motors to a nanotransport device for sorting, separation, or assembly of materials, it is essential to guide microtubules along predetermined pathways (van den Heuvel and Dekker, 2007). Various approaches to design guiding tracks have been investigated, including topographically patterned tracks (Hess et al, 2001;Hiratsuka et al, 2001), chemical patterning of the kinesin attachment sites (Clemmens et al, 2003), a combination of physical and chemical approaches (Cheng et al, 2005), and enclosed microfluidic channels as means for directional confinement (van den Heuvel et al, 2006;Yokokawa et al, 2006).…”

Relationship between Size and Function of Natural Substance Particles

“…For example, ferromagnetic nanoparticles have Intrinsic peroxidase-like activity and can manufacture water and oxygen molecules from hydrogen peroxide [34]. More excitingly, some specialist deliberately designed NPs can manufacture various ChPs [35][36][37][38]. MPs, especially the life MPs, have much more potent functions to manufacture other particles-not only those smaller than themselves but also those much larger than themselves.…”