Biology subjects

Kakugo, A.

Publications and source records attributed to Kakugo, A..

4 recordsLinked to original sources

bioRxiv2025

Force Scaling in Active Swarm of Microtubules via Magnetic Manipulation

Scalability refers to the ability of a system to enhance performance with increasing size. This ability is a defining feature of natural swarms such as ant and bee colonies. Extending this principle to artificial active matter has motivated the creation of molecular swarms composed of myosin-driven actin filaments and kinesin-driven microtubules (MTs). While these swarms exhibit cooperative transport behaviors that surpass the abilities of individual filaments, their collective force generation has remained unquantified. Here, we introduce a straightforward electromagnetic tweezer approach to directly measure the forces generated by MT swarms propelled by surface-bound kinesin motors. We find that force output changes with swarm size, demonstrating quantitative scalability and linking collective organization to mechanical performance. These results establish MT swarms as a model system for scalable, force-producing active matter and provide a foundation for designing biomolecular devices that exploit collective dynamics for microscale actuation and transport. Significance StatementThe cooperative activity of multiple motile agents is observed in nature, known as swarming. In artificial systems, swarming has been demonstrated using active agents like kinesin and MTs, successfully enabling efficient cargo transportation. However, the force generated by the swarm remains unexplored, which is one of the keys to understanding the principles underlying swarm systems. This study introduces a simple method employing electromagnetic tweezers and magnetic beads to measure the force of the MT swarm accurately. The measured forces within the microtubule swarms of different sizes unveil the scaling effect, the additive nature of force generation as the kinesin unit increases. The force study sheds light on the fundamental properties, work performance, efficiency, and execution of the MT swarm.

biophysics↗

bioRxiv2024

Optical Control of Microtubule Accumulation and Dispersion by Tau-Derived Peptide-Fused Photo-Responsive Protein

Microtubules, a major component of the cytoskeleton consisting of tubulin dimers, are involved in various cellular functions, including forming axons and dendrites of neurons and retaining cell shapes by forming various accumulated superstructures such as bundles and doublets. Moreover, microtubule-accumulated structures like swarming microtubule assemblies are attractive components for dynamic materials, such as active matter and molecular robots. Thus, dynamic control of microtubule superstructures is an important topic. However, implementing stimulus-dependent control of superstructures remains challenging. This challenge can be resolved by developing designer protein approaches. We have previously developed a Tau-derived peptide (TP), which binds to the inner or outer surface of microtubules depending on the timing of the incubation. In this report, we designed the TP-fused photo-switchable protein Dronpa (TP-Dronpa) that reversibly photoconverts between monomeric and tetrameric states to photocontrol microtubule assemblies. The formation of microtubule superstructures, including bundles and doublets, was induced by tetrameric TP-Dronpa, whereas monomeric TP-Dronpa ensured that microtubules remained dispersed. Tetrameric TP-Dronpa also induced motile aster-like structures and swarming movement of microtubules on a kinesin-coated substrate. The formation/dissociation of these microtubule superstructures can be controlled by light irradiation. This system can generate and photocontrol various microtubule superstructures and provides an approach to facilitate the assembly of dynamic materials for various applications. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=131 SRC="FIGDIR/small/614838v1_ufig1.gif" ALT="Figure 1"> View larger version (29K): org.highwire.dtl.DTLVardef@fdcc92org.highwire.dtl.DTLVardef@81bf32org.highwire.dtl.DTLVardef@2f7f5eorg.highwire.dtl.DTLVardef@52fc9f_HPS_FORMAT_FIGEXP M_FIG C_FIG

bioengineering↗

bioRxiv2022

Generation of stable microtubule superstructures by binding of peptide-fused tetrameric proteins to inside and outside

Microtubules (MTs) play important roles in biological functions by forming superstructures, such as doublets, triplets, and branched structures, in vivo. Formation of these superstructures by exogenous molecules in vitro will be useful not only for understanding the functions of MTs but also as components of MT-based nanomaterials. Here, we developed a tetrameric fluorescent protein Azami-Green (AG) fused with a His-tag and Tau-derived peptide (TP), TP-AG, which can bind to the inside or outside of MTs depending on the polymerization conditions. The binding of TP-AG to the inside of MTs induced the formation, stabilized, and increased the rigidity of the MTs. The binding of TP-AG to the outside of MTs induced various types of MT superstructures, including doublets, multiplets, and branched structures, by recruiting tubulins to MTs. The formation of motile MT aster structures by TP-AG was also observed. The generation of MT superstructures by these exogenous proteins provides guidelines for the design of MT-based nanomaterials.

bioengineering↗

bioRxiv2021

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.

biophysics↗