TMAO regulates the rigidity of kinesin-propelled microtubules

We demonstrate that the rigidity of the microtubules (MTs), propelled by kinesins in an in vitro gliding assay, can be modulated using the deep-sea osmolyte trimethylamine N-oxide (TMAO). By varying the concentration of TMAO in the gliding assay, the rigidity of the MTs is modulated over a wide range. By employing this approach, we are able to reduce the persistence length of MTs, a measure of MT rigidity, ∼8 fold using TMAO of the concentration of 1.5 M. The rigidity of gliding MTs can be restored by eliminating the TMAO from the gliding assay. This work offers a simple strategy to regulate the rigidity of kinesin-propelled MTs in situ and would widen the applications of biomolecular motors in nanotechnology, materials science, and bioengineering.

Allosteric linkages that emulate a molecular motor enzyme

Allosteric mechanisms are fundamental to the operation of biomolecular motors. Recreating the molecular phenomena associated with allostery, from first principles, would help advance the design and construction of synthetic molecular motors, which remain quite simple compared natural motors. In this study, I present a model for generating allosteric interactions using mechanical linkages, which are devices in which flexible nodes are connected by rigid rods. I describe how allosteric information can be communicated between multivalent binding sites on an enzyme when linkages bind or dissociate in a stepwise fashion, which takes place stochastically according to assigned binding rates and partitioned binding energies. This design allows geometric competitions to autonomously push a linkage enzyme through a desired sequence of states, driven by consumption of a fuel. I use the model to emulate the chemical and conformational cycle of a myosin monomer, which is demonstrated by simulating chemical reaction networks of the linkage structures, and by describing how two linkage monomers can be connected together to construct a motor that walks on a track. This work shows how the complex behavior of biomolecular motors can be recapitulated with simple geometric and chemical principles that encode allosteric mechanisms. Because the concepts are material-agnostic, they can potentially be used to design and construct allosteric machines using various chemistries.

Highly efficient chemically-driven micromotors with controlled snowman-like morphology

A hierarchical catalytic engine and morphology optimization lead to highly efficient micromotors that operate at a fuel concentration and speed close to those of biomolecular motors.

Opposing Pressures of Speed and Efficiency Guide the Evolution of Molecular Machines

Many biomolecular machines need to be both fast and efficient. How has evolution optimized these machines along the tradeoff between speed and efficiency? We explore this question using optimizable dynamical models along coordinates that are plausible evolutionary degrees of freedom. Data on 11 motors and ion pumps are consistent with the hypothesis that evolution seeks an optimal balance of speed and efficiency, where any further small increase in one of these quantities would come at great expense to the other. For FoF1-ATPases in different species, we also find apparent optimization of the number of subunits in the c-ring, which determines the number of protons pumped per ATP synthesized. Interestingly, these ATPases appear to more optimized for efficiency than for speed, which can be rationalized through their key role as energy transducers in biology. The present modeling shows how the dynamical performance properties of biomolecular motors and pumps may have evolved to suit their corresponding biological actions.