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Self-propelled molecular entities enable studying swarm behavior on a macroscopic scale but programmability of interactions has yet not been achieved. Here the authors show reversible regulation of DNA-functionalized microtubules by DNA signals and switching between solitary and swarm behaviour by employing photoresponsive DNA strands.

It is challenging to characterize the mechanical properties of soft surfaces owing to the coupling between surface deformation and elasticity of bulk materials. Here, Inoue et al. use motile cytoskeletal filaments as active probes, whose direction reflects the stress field experienced by the surface.

We have successfully developed a system to perform active self-organization of microtubules (MT) using a streptavidin–biotin interaction in a nitrogen atmosphere (inert chamber). Use of inert chamber dramatically improved the lifetime of assembled microtubules and kept them active for a longer period of time compared to the case without using inert chamber. Longer lifetime of assembled microtubules obtained using the inert chamber would be significantly important in further development of biomolecular motor protein-based organized systems.

We demonstrated biomolecular motors driven swarming of microtubules and their dissociation under UV and visible light irradiation, respectively. A photoresponsive molecule, para tert-butyl-substituted azobenzene was incorporated to the backbone of single strand DNA, which functions as a photoswitch to control the swarming of microtubules in a reversible manner. This work is expected to expand the potential applications of biomolecular motors in developing photoregulated molecular machines.

Stabilization of microtubules occurs by paclitaxel bound to the taxoid site and cevipabulin (and its derivative) bound to the taxoid site and/or vinca alkaloid domain of the β-tubulin in tubulin heterodimer.

Microtubules (MTs) consisting of tubulins are important targets of drugs for MT-related diseases. We have previously designed a linear Tau-derived peptide (TP) that binds to the interior of MTs. In this article, a cyclic TP (TCP) was developed for enhanced binding to tubulin and stabilization of MTs. The fluorescently labeled TCP exhibited a remarkably enhanced binding affinity to tubulin compared to the linear TP. The stabilization of MTs by binding of TCP was demonstrated, such as formation of typically unstable MTs in the presence of guanosine triphosphate.

The graphical abstract shows that the kinesin-driven quantum dot transport along microtubule immobilized on a substrate using glutaraldehyde concentration ≤0.10% (v/v) remain unaltered, whereas, at higher glutaraldehyde concentration, >0.10% (v/v), the quantum dot transportation is slowed down.

Rotating ring-shaped microtubule assemblies were successfully formed on dynein-coated surface through active self-organization process in a similar way to kinesin. However, no preferential direction of rotation was observed in contrast to the aforementioned results of previous kinesin studies. This indicates that dynein is less sensitive to the experimental condition than kinesin.

Recent studies on exploration of mechanical deformation of microtubules under tensile and compressive stress, using a newly developed methodology, have been reviewed. In the first part of this review article, development of the methodology and its utility in studying the mechanoresponsiveness of microtubules have been described. In the second part, applications of the recently developed methodology in studying dynamic soft interfaces have been elaborately discussed.

Recent advances in the study of active self-assembly utilizing biomolecular motors are reviewed. Various methodologies developed for demonstrating active self-assembly of biomolecular motors are discussed in detail with an emphasis on the morphological variations of the self-assembled structures.

Drag force on micron-sized particles in an aqueous medium was determined and compared with that predicted by the Stokes’ law. Effect of a number of parameters such as surface morphology of particles, particle size, and so on on the drag force acting on the microparticles in an aqueous medium was systematically investigated. Surface morphology was found to strongly affect the drag force working on the microparticles. In addition surface charge, roughness, and physical nature of microparticles were also found involved in the alteration of the drag force.